Diisopropylphosphinoyl alkanes as topical agents for the treatment of eye diseases

Abstract

The present invention relates to a method for treating an eye disease in a subject in need of such treatment. The method comprises administering to the subject a composition comprising a therapeutically effective amount of a 1-diisopropylphosphinoylalkane (DIPA) compound. The DIPA compound is a compound selected from DIPA-1-7, DIPA-1-8, and DIPA-1-9. The eye disease includes blepharitis and conjunctivitis.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Application No. 17 / 803,311, filed May 3, 2022, the contents of which are hereby incorporated by reference in their entirety.

Background Art

[0002] The present discovery generally relates to the field of therapeutic compounds. More specifically, the present discovery relates to the specific diisopropylphosphinoylalkanes (DIPA - 1 - 5, DIPA - 1 - 6, DIPA - 1 - 7, DIPA - 1 - 8, DIPA - 1 - 9, and DIPA - 1 - 10, collectively referred to herein as "DIPA compounds"), which are useful, for example, in the treatment of skin symptoms and disorders (such as diseases). Examples of symptoms are sensory abnormalities (such as irritation, burning, itching, or pain), collectively referred to as paresthesia of the skin. Examples of skin - inflammatory disorders are atopic dermatitis, contact dermatitis, anogenital dermatitis, lichen sclerosus, blepharitis, conjunctivitis, psoriasis, and seborrheic dermatitis. When the function of the skin is disrupted, the skin can also cause itching. Itching of the skin occurs in conditions such as urticaria, cholestasis, kidney dialysis patients, psychosomatic diseases, psoriasis, dermatitis, and eczema. The present invention also relates to pharmaceutical compositions containing such compounds, as well as the use of such compounds and compositions, for example, in therapy.

[0003] The skin, the largest organ in the body, is composed of three layers (the epidermis, dermis, and subcutaneous layer). The outermost layer, the epidermis, is only about 1 mm thick and is densely packed with nerve endings. The epidermis produces epithelial cells that form the stratum corneum, a layer of dead cells that does not allow water to pass through. The time it takes for the epidermis to be replaced is about 1.5 months. When the skin is damaged, the main signs of inflammation are the symptoms of heat, redness, swelling, and pain. The damaged tissue causes sensations of irritation, burning, itching, and pain, which are collectively called paresthesia. Itching or pruritus is a sensation that induces the urge to scratch and is a troublesome symptom of skin dysfunction. Itching is a complaint of about 80% of patients who visit dermatology clinics.

[0004] Cooling the body surface refreshes the sensation, reduces discomfort, attenuates pain, reduces itching, and suppresses inflammation. The intensity of cooling can be ranked from a refreshing coldness, a chill, cold, freezing cold, stinging cold, etc. Chemical substances that cool usually do not change the temperature of the tissue. Menthol is an example of a chemical coolant, but due to its irritancy and short duration of action, its use as an analgesic or antipruritic agent is limited. The development of new coolants for itching is hindered by the stratum corneum, a troublesome barrier for drugs to penetrate the nerve endings in the epidermis.

[0005] The cloning of TRP channels about 25 years ago (1998 - 2002) has improved the understanding of the neural circuits of skin temperature sensation and paresthesia. This research reached its pinnacle with the 2021 Nobel Prize to its pioneers, David Julius and Ardem Patapoutian. Currently, the language to explain skin pathology has become more precise, and new drugs targeting specific TRP receptors in nerve endings have been devised to treat paresthesia and itching.

[0006] 1-Dialkylphosphinoylalkanes [DAPA] are solvent-like molecules that require several [1-3] steps for synthesis. They are also known as trialkylphosphine oxides or dialkylphosphorylalkanes. When two of the alkyl groups of DAPA are isopropyl, the abbreviation of DAPA is changed to DIPA [diisopropylphosphinoylalkane].

[0007] Rowsell and Spring [Phosphine oxides having a physiological cooling effect. US 4,070,496. Jan 24., 1978] describe a series of phosphine oxides having a physiological cooling effect on the skin and oral cavity. For example, see: the table in columns 3 and 4 thereof. Ten of the compounds shown therein (Table 1) have one isopropyl group (designated as iso-C3H7). None of the compounds have two isopropyl groups. Siddall et al. [Simplified preparation of some trisubstituted phosphine oxides. J. Chemical Engineering Data 10:303-305, 1965] reported the synthesis of 1-diisopropyloctane [DIPA-1-8], but Siddall et al. did not investigate the biological activity of this molecule.

Table 1

Summary of the Invention

[0008] In this discovery, it has been found that structurally modifying a specific 1-dialkylphosphinoylalkane (DAPA) to a 1-diisopropylphosphinoylalkane (DIPA) analog results in an agent that strongly induces a "dynamic coldness" sensation when applied to the skin. The 1-diisopropylphosphinoylalkane described herein is referred to as a "DIPA compound" or "DIPA". The DIPA compound does not affect tissue temperature, but reduces paresthesia and itching of skin damage. The outstanding characteristics of DIPA are that it is water-soluble, easy to formulate, can penetrate intact skin (e.g., the face, eyelids, or ocular surface) to reach epidermal targets, its anti-itch effect is rapidly manifested, and the effectiveness of itch treatment persists for several weeks of use without loss of effect. This reduction in paresthesia and itching is called "cooling sensation", and the neural circuit proposed as the mechanism of action of DIPA is shown in FIG. 1.

[0009] New clinical trial data are presented showing that the cooling sensation reduces urticaria and scalp itching. Additional data show that DIPA is effective in the itching of cholestasis, lichen sclerosus, blepharitis, and conjunctivitis.

[0010] Furthermore, the applicant unexpectedly discovered that the DIPA compounds described herein are effective in the treatment of eye diseases, such as dry eye symptoms, blepharitis, or conjunctivitis (e.g., allergic conjunctivitis or non-infectious conjunctivitis).

[0011] Figure 1 is a diagram of a method for reducing paresthesia in skin diseases (a mechanism called "cool sensation") by a DIPA compound. Harmful stimuli activate small-diameter C fibers in the peripheral receptive field and transmit signals that cause paresthesia. When a DIPA TRPM8 agonist is applied to the receptive field, larger myelinated Aδ fibers that transmit cold signals are activated (≤25°C). These signals are modality-specific. The cell bodies of primary afferent nerves are in the peripheral ganglia (DRG = dorsal root ganglion or cranial ganglion). The afferent signals for pain and cold are integrated in the nuclei of the spinal cord and brainstem. Cool sensation occurs when DIPA-induced TRPM8 signals reduce the paresthesia of pain.

[0012] The skin is a site that is often damaged. The main symptoms of the skin's response to injury (inflammation) are heat sensation, redness, swelling, and pain. Over time, damaged tissue causes irritation, burning, itching, and pain, which are collectively called paresthesia. DIPA molecules reduce the symptoms of paresthesia by dynamic cooling. This reduction effect is called "cool sensation".

[0013] The cloning of TRP channels for sensory transmission has revolutionized the understanding of the neural circuits of temperature sensation and paresthesia. This research reached its peak with the 2021 Nobel Prize to the pioneers of this research, David Julius and Ardem Patapoutian. Currently, specific TRP receptors can be visualized on nerve terminals, and the mechanism of action of drugs can be rationalized. A new view is that dedicated TRPM8 nerve fibers transmit cold signals. Cool sensation (≤25°C at the receptor) is anatomically and modality-specific and has its own preferred circuits and cables. Cooling via TRPM8 induces "cool sensation" and alleviates paresthesia. The neural pathways for cooling and paresthesia do not need to overlap, but preferably originate from the same skin segment. The signals converge in the nuclei of the spinal cord or brainstem. Thus, for example, a cooling signal from the TRPM8 receptive field in the vulva can suppress vulvar itching. Transmission enters the spinal cord via the pudendal nerve from the skin segment of the sacral plexus. Figure 1 shows this mechanism and neural circuit.

[0014] Put simply, the concept of DIPA treatment is like installing a small air conditioner in damaged tissue. The extraordinary properties of DIPA molecules are their water solubility and the ability to penetrate the skin's cell layers and reach the underlying receptor targets. The target for delivery is TRPM8. When TRPM8 is activated, it transmits a cooling sensation. Integrating these signals centrally reduces paresthesia. By alleviating paresthesia, DIPA also has the effect of improving the disease. Patients feel better, sleep well, and the interruption of itching and scratching enables tissue healing. Clinical data are presented to support these observations. The water solubility of the DIPA compound at therapeutically effective concentrations facilitates the formulation of the compound for delivery to TRPM8.

[0015] Another aspect of this discovery relates to a pharmaceutical composition comprising one or more DIPA compounds described herein and a pharmaceutically acceptable carrier or diluent. Particularly preferred embodiments include one or more DIPA compounds and a delivery agent that carries the one or more compounds, and the delivery agent is suitable for topical delivery. These preparations described herein can be used, for example, in a method of treating the body of a human or animal by therapy for use in a method of treating a disease [such as an eye disease, such as dry eye symptoms, pain, itching, blepharitis, or conjunctivitis (such as allergic conjunctivitis or non-infectious conjunctivitis)]. For example, a preferred embodiment for reducing vulvar itching is a topical 1% DIPA-1-8 solution or 0.5% gel in water or saline.

[0016] Accordingly, this discovery proposes a treatment method for treating paresthesia of skin diseases or eye diseases in a subject in need of treatment. The method includes topically administering to the skin of the subject a liquid or semi-liquid composition containing a therapeutically effective amount of one or more compounds having Formula 1: [Chemical formula] (wherein R is n-hexyl, n-heptyl, n-octyl, or n-nonyl).

[0017] In some embodiments, the compound having Formula 1 is a 1-diisopropylphosphinoylalkane (DIPA) compound, and R is n-hexyl, n-heptyl, n-octyl, or n-nonyl.

[0018] In some embodiments of the present invention, the DIPA compound is a compound selected from the following compounds:

Chemical formula

[0019] In some embodiments, the administration is topical administration.

[0020] In some embodiments, the composition is administered to the ocular surface of the subject, the skin around the eye(s), the eyelid(s), or other parts of the face.

[0021] In some embodiments, the composition is a liquid or semi-liquid composition suitable for the concentrated delivery of the DIPA compound to the ocular surface of the subject.

[0022] In some embodiments, the composition is a liquid containing water or isotonic saline as a solvent.

[0023] In some embodiments, the DIPA compound is dissolved in the composition or present as micelles.

[0024] In some embodiments, the DIPA compound has a concentration of 0.5 to 20 mg / mL.

[0025] In some embodiments, the composition is a liquid composition containing the DIPA compound at a concentration of 0.5 to 5 mg / mL or 1 to 5 mg / mL.

[0026] In some embodiments, the eye disease is blepharitis or conjunctivitis (e.g., allergic conjunctivitis or non-infectious conjunctivitis).

[0027] In some other embodiments, the eye disease is itching or pain in the eye(s) or the skin area around the eye(s).

[0028] In some embodiments, the administration of the formulation for the method of the present invention is topical administration to the eyelid(s) of the subject or another skin area around the eye(s).

[0029] In some embodiments, the administration of the formulation is at least once a day or at least twice a day.

[0030] In some embodiments, the administration of the formulation is for at least one week.

[0031] In some embodiments, the administration of the formulation for treating the eye disease described herein is by wipe, towel, eye drop device, or cream tube.

[0032] The liquid or semi - liquid composition used in the method of the present invention penetrates the skin of the subject after topical application and effectively reduces or eliminates inflammation or infection at or near the location where the composition is administered.

[0033] Another aspect of the present invention is the use of a compound of formula 1 (e.g., a DIPA compound, e.g., DIPA - 1 - 6, DIPA - 1 - 7, DIPA - 1 - 8, or DIPA - 1 - 9) in the manufacture of a medicament for treating an eye disease by topical administration to another area of the skin around the eyelid(s) or eye(s) of a subject in need of treatment.

[0034] Examples of eye diseases include dry eye symptoms, blepharitis, conjunctivitis (e.g., allergic conjunctivitis or non - infectious conjunctivitis), itching or pain in the skin around the eye(s), etc. The novel features of the present invention are described in detail in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by referring to the following detailed description, which shows exemplary embodiments in which the principles of the present invention are utilized, and the accompanying drawings.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0036] Specific features of the present invention and / or references to non-limiting embodiments are made. It should be understood that the disclosure of the invention herein includes any possible combination of such specific features. For example, if a specific aspect or embodiment of the present invention, or a specific feature is disclosed in the context of a particular claim, that feature can, to the extent possible, be combined with other specific aspects and embodiments of the present invention and / or in that context, be used throughout the present invention.

[0037] This discovery relates to specific compounds (the DIPA compounds described herein) that, when delivered to the skin, selectively and potently cause a "dynamic coldness" or cool feeling for at least several hours. The dynamic coldness can be repeated without significantly reducing the effect and can persist throughout the day. Accordingly, these compounds have use in the treatment of skin discomfort, particularly skin irritation, itching, and pain.

[0038] In one aspect, the present invention provides a method for treating an eye disease in a subject in need of such treatment. The method includes topically administering a liquid or semi-liquid composition to the skin of the subject, the composition comprising a therapeutically effective amount of one or more compounds having Formula 1. [Chemistry] (wherein R is n-heptyl, n-octyl, or n-nonyl).

[0039] In some embodiments, the method comprises administering to the subject a composition comprising a therapeutically effective amount of a 1-diisopropylphosphinoylalkane (DIPA) compound.

[0040] The compositions described herein can be administered to human patients as such, or in pharmaceutical compositions mixed with other active ingredients, such as in combination therapy, or as carriers, diluents, excipients, or combinations thereof. Suitable formulations vary depending on the route of administration selected. Techniques for formulating and administering the compounds described herein are known to those of skill in the art.

[0041] As used herein, "carrier" refers to a compound that facilitates the incorporation of a compound into cells or tissues. For example, but not limited to, dimethyl sulfoxide (DMSO), ethanol (EtOH), or PEG400 are commonly used carriers that facilitate the uptake of many organic compounds into target cells or tissues.

[0042] As used herein, "diluent" refers to a component in a pharmaceutical composition that lacks pharmacological activity but may be pharmaceutically necessary or desirable. For example, a diluent can be used to increase the volume of a potent drug that is too small in mass to be manufactured and / or administered. It can also be a liquid for dissolving a drug administered by injection, oral ingestion, or inhalation. A common form of diluent in the art is a buffered aqueous solution (e.g., but not limited to, phosphate buffered saline that mimics the composition of human blood).

[0043] As used herein, "excipient" refers to an inert substance that is added to a pharmaceutical composition to impart, among other things, bulk, consistency, stability, binding, lubricity, disintegrating power, etc. to the composition. "Diluent" is a type of excipient.

[0044] As used herein, "therapeutically effective amount" refers to an amount of a DIPA compound sufficient to provide a reasonable benefit / risk ratio applicable to any drug treatment. However, it will be understood that the total daily usage of the DIPA compound can be determined by the attending physician within the scope of sound medical judgment. The specific therapeutically effective dosage level for a particular subject will depend on various factors (e.g., the disorder being treated and the severity of the disorder; the specific composition used, the age, weight, general health, sex, and diet of the subject; the time of administration, route of administration, and excretion rate of the DIPA compound used; the duration of treatment; drugs used in combination with or concurrently with the DIPA compound; and similar factors well known in the medical arts). For example, it is known in the art to initiate administration of a compound at a level lower than that required to achieve the desired therapeutic effect and to gradually increase the dosage until the desired effect is achieved. In addition, "therapeutically effective amount" is an amount that induces a biological or medical response in a tissue, system, or subject sought by a researcher or clinician, and in particular, induces a desired therapeutic or prophylactic effect against an eye disease.

[0045] One of ordinary skill in the art will recognize that the amount can be considered therapeutically "effective" even if the condition is not completely eradicated or prevented, but the condition or the symptoms and / or effects of the condition are partially improved or alleviated in the subject. Various indicators for determining the effectiveness of a method for improving an eye disease are known to those of ordinary skill in the art.

[0046] As used herein, the terms "treating," "treatment," "therapeutic," or "therapy" do not necessarily mean the complete cure or elimination of a disease or condition. Any degree of alleviation of the undesirable signs or symptoms of a disease or condition can be considered treatment and / or therapy. Furthermore, treatment may include actions that can worsen the overall health or appearance of a patient.

[0047] In some embodiments of the present invention, the DIPA compound is a compound selected from the following compounds:

Chem.

[0048] The DIPA compound is water-soluble and rapidly produces a strong and intense cooling sensation on the skin. The chemical feature of the DIPA compound, which is the smallest active alkyl side chain adjacent to the phosphine oxide, is that the polar phosphine oxide group is exposed by water, enhancing the water solubility.

[0049] In some embodiments, the administration is topical. As used herein, the term "topical administration" refers to delivery to the surface of the body that is in contact with air.

[0050] In some embodiments, the composition is administered to the ocular surface of a subject.

[0051] The ocular surface includes the outer layer of the cornea, tears, conjunctiva, and the edges of the eyelids. This part of the eye has the most frequent damage and the occurrence of eye diseases due to direct exposure to the environment.

[0052] In some embodiments, the composition is a liquid or semi-liquid composition suitable for the concentrated delivery of the DIPA compound to the ocular surface of a subject.

[0053] The term "concentrated delivery" means obtaining the desired effect (avoiding excessive stimulation and exerting gentle cooling). The receptor target of the DIPA compound on the nerve endings is embedded in the epithelial cell layer. The thickness of the epidermis is only about 1 mm, but there are many dead cell layers (stratum corneum) composed of denatured proteins that prevent agonist molecules from accessing the nerve endings. The heel of the foot is the thickest barrier (86 cell layers in the heel), followed by the palm of the hand, and then the back of the hand. The eyelid is the thinnest, with 4 to 8 cell layers. The limbs, arms, and legs, as well as the torso (back), have thicker surfaces. The scalp is intermediate. These differences are important for the action of the drug. In the case of the eyelid, in order to obtain the desired effect, the compound and other components must be carefully selected: avoid excessive stimulation and perform gentle cooling.

[0054] In some embodiments, the composition is a liquid containing water or isotonic saline as a solvent.

[0055] In some embodiments, the DIPA compound has a concentration of 0.5 to 20 mg / mL.

[0056] In some embodiments, the composition is a liquid composition containing a DIPA compound at a concentration of 0.5 to 5 mg / mL or 1 to 5 mg / mL.

[0057] In some embodiments, the eye disease is blepharitis or conjunctivitis.

[0058] Blepharitis is an inflammation of the eyelids. It is a common eye condition where the eyelids are red, swollen, irritated, and itchy. It can cause hard, scaly flakes on the eyelashes. Blepharitis usually affects both eyes along the edges of the eyelids. Blepharitis usually occurs when small oil glands near the base of the eyelashes become clogged, causing irritation and redness. Several diseases and conditions can cause blepharitis.

[0059] Conjunctivitis (pink eye) is an inflammation or infection of the transparent membrane (conjunctiva) that covers the inner surface of the eyelids and the white part of the eyeball. When the small blood vessels in the conjunctiva become inflamed, they become more visible. This is what causes the white of the eye to appear red or pink. Infectious conjunctivitis is usually caused by a bacterial or viral infection, an allergic reaction, or in infants, an incomplete opening of the tear ducts. Infectious conjunctivitis can be irritating but rarely affects vision. Treatment can help relieve the discomfort of infectious conjunctivitis.

[0060] In some embodiments, the conjunctivitis is allergic conjunctivitis.

[0061] Allergic conjunctivitis is a local allergic condition of the eyelids (blepharitis) and conjunctiva. This condition can cause significant impairment to the quality of life due to persistent eye itching, and in severe cases, there is a potential functional disorder in visual function. Subcategories of allergic conjunctivitis are: a) seasonal and perennial allergies (IgE-mediated allergies), b) atopic keratoconjunctivitis (associated with atopic eczema), c) vernal catarrh (a subset of immune diseases, 50% of which are IgE-related), d) contact eyelid conjunctivitis (similar to contact dermatitis, e.g., use of eye makeup), and e) giant papillary conjunctivitis (associated with the use of contact lenses). The common element of the symptoms is eye itching.

[0062] In some embodiments, the administration is topical administration to the subject's eyelids.

[0063] In some embodiments, the administration is at least once a day.

[0064] In some embodiments, the administration is at least twice a day. In some embodiments, the administration is once in the morning and once in the evening.

[0065] In some embodiments, the administration is for at least one week.

[0066] In some embodiments, the administration is by wiping.

[0067] The composition can be provided in a suitable package and / or a suitable container. For example, the composition can be provided as a swab, wipe, pad, or towel (e.g., appropriately sealed with a wrap) having a DIPA compound or a composition containing the DIPA compound.

[0068] Similarly, the composition can be provided as an aerosol spray delivered from a pressurized container.

[0069] Furthermore, the composition can be provided by a manually operated nebulizer (e.g., having a suitable small orifice) connected to a reservoir containing a DIPA compound or a composition containing a DIPA compound, which can deliver, for example, a unit volume (e.g., 0.05 - 0.15 mL) to the skin surface.

[0070] Definitions Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Unless otherwise noted, all patents, applications, published applications, and other publications referenced herein are incorporated by reference in their entirety. In the event that there are multiple definitions for a term in this specification, the definitions in this section shall control, unless otherwise noted.

[0071] Allergic conjunctivitis. Approximately 15% of the world's population suffers from allergic diseases with eye lesions (Leonardi A. Allergy and allergic mediators in tears. Exp Eye Res. 2013;117:106 - 17). Allergic conjunctivitis is a local allergic condition of the eyelids (blepharitis) and conjunctiva. This condition can significantly impair the quality of life due to persistent eye itching and, in severe cases, there is a potential impairment of visual function. Sub - categories of allergic conjunctivitis are: a) seasonal and perennial allergy (IgE - mediated allergy), b) atopic keratoconjunctivitis (associated with atopic eczema), c) vernal catarrh (a subset of immune diseases, 50% being IgE - related), d) contact eyelid conjunctivitis (similar to contact dermatitis, e.g., use of eye makeup), and e) giant papillary conjunctivitis (associated with the use of contact lenses). Conjunctivitis can occur even without an allergic etiology (e.g., exposure to chemical irritants). A common element of the symptoms is eye itching.

[0072] Atopic dermatitis (eczema) is an inflammatory skin disease. Any part of the skin can become itchy and inflamed. Lesions (e.g., excoriated lesions) usually appear on the flexures of the elbows and knees. The reason is probably that these areas sweat more. Many patients with atopic dermatitis also suffer from allergic rhinitis and asthma. The symptoms are more common in children and young adults than in adults. Recently, two new therapeutic agents for atopic dermatitis (dupilumab (a monoclonal antibody) and crisaborole (an ointment)) have been approved by the US FDA. Both therapeutic agents have a slow onset of therapeutic effect over six weeks or more. Dupilumab is very expensive as a one-year treatment. The effectiveness of crisaborole is modest and it is an oily ointment, which is not preferred by atopic patients. The side effect of dupilumab in eczema patients is blepharitis, which can be reduced with DIPA administered using an eye wipe.

[0073] Pruritus of cholestasis. In certain systemic diseases (e.g., cholestasis, renal insufficiency and kidney dialysis, liver insufficiency, and lymphoma), there are blood-borne pruritogens that cause generalized itching. The exact chemical identification of these pruritogens is not fully established, but in the case of liver disease and kidney dialysis patients, it is likely to be bile acids. The itching is intense and causes great distress to the patient. During pregnancy, several subjects also develop intense cholestatic pruritus for which no drug treatment is known. The itching is not accompanied by skin inflammation.

[0074] Dermatological diseases are diseases of the skin, nails, or hair. The skin has three layers (the epidermis, dermis, and subcutaneous layer). The epidermis includes a keratinized stratum corneum. The eyelids, cornea, tongue, and parts of the buccal cavity are keratinized and are thus considered skin. Mucous membranes, which are the internal surfaces of the body, do not have a keratin layer. The skin is the largest organ in the body, although the epidermis is only about 1 mm thick. The epidermis is densely populated with nerve endings. The turnover time of the epidermis, i.e., the time it takes to replace, is about 1.5 months. Inflammation can occur in all three layers of the skin, but itching mainly originates from the epidermis. Approximately 80% of patients who visit a dermatologist complain of itching (J. Rinaldi. The itch-scratch cycle. Dermatology, Practical and Conceptual 9:90-97, 2019).

[0075] Dermatomal segments. In the body, the area innervated by a single spinal nerve is called a dermatomal segment. Because of the overlap in the somatic organization of sensory projections, input from immediately adjacent dermatomal segments can affect the sensation at one location. This overlap of sensory input is called convergence. A good example of the convergence mechanism in antinociception is itching and scratching. Mechanoreceptors are activated by scratching, reducing itching, but it is not necessary to scratch exactly at the point that causes the itching. Adjacent areas are sufficient.

[0076] DIPA compounds. DIPA is an abbreviation for 1-[diisopropylphosphinoyl]alkane. The third alkyl group in the molecule can be described by a number; i.e., 4, 5, 6, 7, 8, 9, and 10 correspond to butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decanyl side chains, respectively. These alkanes have a linear or "straight-chain [n]" configuration, and the phosphinoyl group is attached to the primary or "1" position of the carbon chain of the third side chain. These compounds are also known as trialkylphosphine oxides or 1-dialkylphosphorylalkanes.

[0077] Abnormal sensation. When the body's surface is damaged, nerve endings that transmit signals interpreted by the brain as "discomfort" or "abnormal sensation" (feeling unwell) are activated. Examples of abnormal sensations include pain, irritation, itching, burning, and stinging. Abnormal sensation is a general term representing discomfort and is more inclusive than terms such as "pain" or "itching". Abnormal sensation is prominent when the epithelium and transitional epithelium are chronically damaged.

[0078] The scratching in the vicious cycle of itching and scratching relieves itching, but dangerous itching and scratching can cause further damage to the skin, perpetuate inflammation, and lead to excoriation and lichenification that impairs appearance. The vicious cycle of itching and scratching is a well-known phenomenon in childhood and canine atopy, and preventive measures are taken to prevent the subject from scratching the inflamed and itchy sites. Itching interferes with sleep, and patients with atopic dermatitis will scratch their bodies violently even during sleep. An effective therapeutic agent should prevent itching and act long enough for the subject to fall asleep within a few minutes after application. Since scratching can occur after the subject falls asleep, the subject must be instructed to apply the therapeutic agent after washing, use it as needed, and apply it before going to bed at night. This is particularly important for children. This therapeutic agent should also interrupt the vicious cycle of itching and scratching, thereby promoting healing.

[0079] Pruritus after burns. During the recovery period after burns, the healing skin becomes extremely itchy. Clinically, pruritus after burns tends to be refractory to conventional treatments. Preliminary studies indicate that DIPA-1-7 gel is effective in reducing pruritus after burns.

[0080] The receptive field of a sensory neuron is the area within space where a stimulus changes the firing of the neuron. The receptive field is spatially determined by the distribution of the neuron's nerve endings. In the case of the epithelium, the nerve endings mesh with the cell layer of the basal layer of the epithelium. The receptive field, even if smaller than 1 mm2, can completely dominate the attention of the brain and mind when activated by an appropriate stimulus (e.g., nociception or pruritus). Witness what happens when a sharp pin or needle touches the skin, or when a dog is distracted by being bitten by a flea.

[0081] Itching of the scalp. Sensory information from the scalp (e.g., the vertex or occipital region) is transmitted by branches of the trigeminal nerve and cervical nerves (V1: ophthalmic nerve of the trigeminal nerve, V2: maxillary nerve of the trigeminal nerve, V3: mandibular nerve of the trigeminal nerve, C2: second cervical nerve, C3: third cervical nerve). The hair bulbs of the hair follicles on the scalp have a dense nerve distribution. Seborrheic dermatitis is an inflammatory disease partially caused by fungal infection. It occurs on the scalp and can cause dandruff and itching. Psoriasis is another common cause of itching of the scalp (especially the scalp at the hairline).

[0082] TRP channels. The transient receptor potential (TRP) family of cation channels are peripheral detectors of temperature and nociception and pain stimuli. These receptors on sensory neurons respond to stimuli by activating the action potentials of nerve activity that are converted into sensations. The TRPM8 receptor transduces cold extraction. Through the TRP signal, organisms can detect, respond to, and adapt to external stimuli.

[0083] Urticaria, also known as urticarial papules, is a disease characterized by the sudden onset of "wheals" (raised, itchy bumps on the skin) on any part of the body. Wheals can be very large and concerning, but are not life-threatening. The triggers are usually allergies to foods (e.g., seafood), but there are multiple triggers. Although the skin layer is intact, the release of histamine from the mast cells in the epidermis and dermis causes the wheals and itching. The symptoms can be treated with oral antihistamines and, in severe cases, with oral prednisone or Ig-E antibodies, but it takes about 12 hours for the drugs to take effect. Urticaria is a recurrent condition and, in some patients, can persist for more than 6 weeks (chronic urticaria). The worsening of appearance due to itchy red wheals on the skin is a troublesome feature of urticaria.

[0084] Anatomy and Itching of the Vulva. The female genitalia consist of the vulva, which has outer and inner "lips" (called the labia majora and labia minora, respectively), and accessory structures including the urethra, vaginal vestibule, and vagina. The perineum is the area that extends from below the vulva to the anus. The anorectal region is innervated by the pudendal nerve, which transmits pain messages and other sensations from the vulva. The perineal nerve originates from the sacrum, passes through the pelvis, and enters the vulvar region from the ilium. Branches of the pudendal nerve include the inferior rectal nerve, perineal nerve, and dorsal nerve of the clitoris. These nerves provide sensory information and control urination, defecation, and orgasm. Itching of the vulva is a common condition frequently seen in clinics due to various causes. This topic has been reviewed (Raef HS, Elmariah SB. Vulvar Pruritus: A Review of Clinical Associations, Pathophysiology and Therapeutic Management. Front Med. 2021;8(April):1 - 10), and the information is incorporated herein by reference (in the case of men, the penis is the cause of itching). Damage and inflammation of the anorectal surface and structures cause abnormal sensations of itching and pain in the vulva, which occur frequently due to allergies, immune disorders, infections, hormonal imbalances, or trauma. Vulvar pain and dyspareunia are abnormal sensations that can occur even without anatomical evidence of tissue damage. Lichen sclerosus is an inflammatory condition that affects the anorectal surface and causes severe itching.

[0085] DIPA compound The discovered DIPA compound is achiral and is an example of 1 - dialkylphosphinoylalkane [(O=)PR 1 R 2 R 3 , where R 1 , R 2 , and R 3 are each alkyl groups. In particular, R 1 and R 2 are isopropyl, and R 3 is a straight - chain alkyl group of 5 to 9 carbons and has the general formula of Formula 1 below:

Chemical formula

[0086] Chemical synthesis The DIPA compound was prepared by the following general method: 100 mL (23.7 g, about 200 mmol) of isopropylmagnesium chloride (or in the case of the di-sec-butyl derivative, sec-butylmagnesium chloride) was obtained from Acros as a 25% solution in tetrahydrofuran (THF) and placed in a 500 mL flask (with a stir bar) under nitrogen. A THF solution of diethyl phosphite (Aldrich, D99234, 8.25 g (60.6 mmol) in 50 mL) was added dropwise. After about 30 minutes, the reaction mixture was warmed to boiling. The reaction mixture was stirred for an additional 30 minutes, and then a suitable n-alkyl iodide THF solution (manufactured by TCI; 60 mmol in 20 mL) was added dropwise. Next, the reaction mixture was stirred at room temperature overnight. The reaction mixture was diluted with water, transferred to a separatory funnel, acidified with acetic acid (about 10 mL), and extracted twice with ether. The ether layer was washed with water and evaporated (RotaVap Buchi, bath temperature 40 °C). The light brown oil was distilled under high vacuum. The final product confirmed by mass (determined by mass spectrometry) was a colorless transparent liquid. The synthesis was carried out by specialist chemists at Phoenix Pharmaceuticals, Inc. (Burlingame, California), Uetikon Laboratories (Rahr, Germany), and Dong Wha Pharmaceuticals (Seoul, Korea). The compounds in Table 2 are embodiments of the present invention. The following compounds (Table 3) were also prepared by this general synthetic method and used for comparison. [Table 3-1] [Table 3-2]

[0087] The 3,4-X series are "mixed" isopropyl-sec-butyl compounds (Table 3). These were synthesized by Dr. Jae Kyun Lim (Dong Wha Pharmaceuticals) using the method described below. Briefly, as shown in the following scheme, triethyl phosphite (A) was reacted with sec-butylmagnesium bromide (B), and then hydrolyzed with dilute hydrochloric acid to obtain the monoalkyl compound (C). Next, the product (C) was reacted with isopropylmagnesium bromide (D) to obtain the dialkyl compound (E), which was then reacted with a suitable alkyl iodide (F) to obtain the desired trialkylphosphine (G).

Chemical formula

[0088] General observations on exceptional properties The DIPA compound is a colorless liquid with a density lower than that of water. DIPA-1-7, DIPA-1-8, and DIPA-1-9 of preferred embodiments exhibit a cooling effect that can regulate skin paresthesia caused by various dermatitides (e.g., atopic dermatitis or urticaria) and mucous membranes (especially DIPA-1-8 and DIPA-1-9). Similar structures were described in US4,070,496 (1978) by Rowsell and Spring over about 40 years ago but have not appeared in the scientific literature. All of the '496 structures (Table 1) have their "head" (phosphine oxide group) covered by larger lipophilic groups. The applicant pointed out that '496 does not contain diisopropyl analogs. The applicant synthesized these analogs (which are achiral, in contrast to the structure of '496 where more than 95% are chiral). The applicant found that by minimizing the two alkyl side chains to diisopropyl, the "head" of the prototype molecule is highly polar (hydrophilic) and highly miscible in the polar environment of water. This increase in water solubility is significant (Table 4), being at least 10 times that of DIPA in the case of di-sec-butyl or mixed isopropyl-sec-butyl analogs. The DIPA analogs can move in the extracellular fluid, penetrate between cells, and access the nerve endings in the basal layer.

Table 4

[0089] When the DIPA compound is applied to the facial skin as an aqueous solution of 1 to 10 mg / mL or a 1% hydrogel, there is almost no irritation. For certain analogs, when a solution with a concentration of 1 to 10 mg / mL is brought into contact with the skin around the eye socket or on the cheekbone, a feeling of "dynamic coldness" occurs within 1 minute after application. When applied once, this feeling of "vitality surging" is generated and can relieve fatigue over several hours. In particular, DIPA-1-7 has a strong dynamic cooling.

[0090] When DIPA and related dicyclobutyl analogs are administered around the eye socket, residues will remain on the skin of the eyelid. For example, when the eyelid gets wet, such as by taking a shower or sweating, the residual compound will run off the cornea and cause stinging and irritation. This will limit the options of compounds, for example, in applications where delivery in blepharitis and conjunctivitis is to the skin of the eyelid. Among the compounds of Formula 1, DIPA-1-8 and DIPA-1-9 have minimal residual irritation and are thus particularly useful for the long-term treatment of abnormal eye sensations. The effectiveness of DIPA-1-9 in the treatment of patients with "dry eye syndrome" has been demonstrated in Case Study 7. DIPA-1-7 is more useful for applications where the sensory effect is immediate and energizing. Both DIPA-1-7 and DIPA-1-8 are useful for the treatment of cutaneous paresthesia (e.g., skin irritation, skin itching, or skin pain). DIPA-1-8 has a slightly longer action time than DIPA-1-7.

[0091] Composition. One aspect of the present discovery relates to a composition (e.g., a pharmaceutical composition) comprising a DIPA compound described herein and a pharmaceutically acceptable carrier, diluent, or excipient. Another aspect of the present discovery relates to a method for preparing a composition (e.g., a pharmaceutical composition) comprising mixing a DIPA compound described herein with a pharmaceutically acceptable carrier, diluent, or excipient.

[0092] In one embodiment, the composition comprises a DIPA compound at a concentration of 0.005 to 2.0% wt / vol. In one embodiment, the composition is a liquid or semi-liquid composition (lotion, cream, or ointment) and comprises a DIPA compound at a concentration of 0.5 to 20 mg / mL. In one embodiment, the composition is a liquid composition and comprises a DIPA compound at a concentration of 1 to 5 mg / mL. In one embodiment, the composition is a liquid composition and comprises a DIPA compound at a concentration of 5 to 10 mg / mL. In one embodiment, the composition is a liquid composition and comprises a DIPA compound at a concentration of 10 to 20 mg / mL. The composition can be provided in a suitable package and / or a suitable container. For example, the composition can be provided as a swab, wipe, pad, or towel (e.g., appropriately sealed with a wrap) having the DIPA compound or a composition containing the DIPA compound. Similarly, the composition can be provided, for example, as a patch (e.g., a controlled release patch) suitable for application to the skin (e.g., the skin over the supraclavicular fossa or the sternocleidomastoid muscle). Similarly, the composition can be provided as an aerosol spray delivered from a pressurized container. Similarly, the composition can be provided with a manually operated nebulizer (e.g., having a suitable small orifice) connected to a reservoir containing the DIPA compound or a composition containing the DIPA compound, which can deliver a unit volume (e.g., 0.05 to 0.15 mL) to, for example, the skin surface.

[0093] Use in the manufacture of a medicament. Another aspect of the present discovery relates to the use of the DIPA compounds described herein in the manufacture of a medicament, for example, for use in a method of treating a disorder (e.g., a disease) described herein. In one embodiment, the medicament comprises a DIPA compound.

[0094] Method of treatment. Another aspect of the present discovery relates to a method of treating a disorder (e.g., a disease) described herein, for example, the method preferably comprises administering, in the form of a pharmaceutical composition, a therapeutically effective amount of the DIPA compounds described herein to a subject in need of treatment.

[0095] Disorders to be treated. In one embodiment (e.g., use in a treatment method, use in the manufacture of a medicament, method of treatment), the treatment is the following: sensory discomfort (e.g., caused by irritation, itching, or pain); paresthesia; atopic dermatitis; contact dermatitis; nodular prurigo; urticaria; miliaria rubra; lichen sclerosus; anogenital dermatitis; acne; acneiform eruption; pruritus in the elderly, pruritus due to cholestasis and liver diseases, pruritus due to lymphoma, pruritus due to renal dialysis, seborrheic dermatitis; psoriasis; eczema; eye pain and discomfort; and itching due to the healing of burns.

[0096] As used herein, the term "sensory discomfort" relates to irritation, itching, pain, or other paresthesia (abnormal sensation, e.g., a burning sensation, or a sensation of the presence of a foreign body, or a prickling sensation) from the body surface. The term means the activation of nociceptors at the sensory nerve endings of the body. Nociceptors are stimulated, for example, by high temperature, mechanical pressure, chemicals (e.g., capsaicin, acidity, contaminants), trauma, inflammation, and inflammatory mediators. DIPA compounds (e.g., DIPA-1-7 or DIPA-1-8) that reduce sensory discomfort can be called anti-nociceptive agents.

[0097] In one embodiment, the sensory discomfort is a stimulus, itching, or pain. In one embodiment, the sensory discomfort is caused by cutaneous dysesthesia. In one embodiment, the cutaneous dysesthesia is a skin stimulus, skin itching, or skin pain. In one embodiment, the sensory discomfort is caused by atopic dermatitis. In one embodiment, the sensory discomfort is caused by canine atopic dermatitis. In one embodiment, the treatment is a treatment for cutaneous dysesthesia. In one embodiment, the treatment is a treatment for dermatitis. In one embodiment, the treatment is a treatment for atopic dermatitis. In one embodiment, the treatment is a treatment for canine atopic dermatitis. In one embodiment, the treatment is a treatment for contact dermatitis. In one embodiment, the treatment is a treatment for urticaria. In one embodiment, the treatment is a treatment for the pruritus of the elderly. In one embodiment, the treatment is a treatment for the pruritus of miliaria rubra. In one embodiment, the treatment is a treatment for the pruritus (cholestasis) of liver disease. In one embodiment, the treatment is a treatment for the pruritus of kidney dialysis patients. In one embodiment, the treatment is a treatment for the pruritus of lymphoma patients. In one embodiment, the treatment is a treatment for the sensory abnormalities of psoriasis. In one embodiment, the treatment is a treatment for the sensory abnormalities of neurogenic / neuropathic itching. In one embodiment, the treatment is a treatment for the sensory abnormalities of lichen sclerosus. In one embodiment, the treatment is a treatment for the discomfort of the eyes. In one embodiment, the discomfort of the eyes is caused by: eye strain; visual fatigue; ophthalmic surgery; airborne irritants or contaminants that interact with the surface of the eyes; prolonged wearing of contact lenses; excessive exposure to sunlight; conjunctivitis; conjunctivitis in atopic dermatitis patients treated with dupilumab; or dry eye syndrome. In one embodiment, the treatment is a treatment for miliaria rubra. In one embodiment, the treatment is a treatment for transmitting a refreshing feeling to the skin of a human or mammal.

[0098] Treatment. As used herein in the context of treating a disorder, the term "treatment" generally relates to the treatment of a human or animal (e.g., for veterinary use) in which some desired therapeutic effect (e.g., inhibition of the progression of a disorder) is achieved, including reduction in the rate of progression, arrest of the rate of progression, alleviation of symptoms of the disorder, improvement of the disorder, and cure of the disorder. Treatment as a prophylactic measure (i.e., prophylaxis) is also included. For example, use in a patient who has not yet developed a disorder but is at risk of developing the disorder is encompassed by the term "treatment." As used herein, the term "therapeutically effective amount" refers to the amount of a compound, or a material, composition, or dosage form containing the compound, that is effective to produce some desired therapeutic effect when administered in accordance with a desired treatment regimen and that provides a reasonable benefit / risk ratio.

[0099] Combination therapy. The term "treatment" includes combination treatments and therapies in which two or more treatments or therapies are combined, e.g., sequentially or simultaneously. For example, the DIPA compounds described herein can also be used in combination therapy (e.g., in combination with another agent). One aspect of the present discovery relates to the DIPA compounds described herein in combination with one or more (e.g., 1, 2, 3, 4, etc.) additional therapeutic agents. The specific combinations will be left to the discretion of a physician or pharmacist who selects the dosage using general knowledge and the dosing regimens known to the skilled practitioner. Examples of additional therapeutic agents include the following: anti-inflammatory glucocorticosteroids; analgesics; sympathomimetic amine decongestants; antihistamines; local anesthetics; ophthalmic lubricants or irrigants; sunblock ingredients; anti-acne agents; keratolytics; antihemorrhoidal agents; agents for vulvar itching or discomfort; antibiotics; skin emollients; or anti-skin aging agents.

[0100] Route of administration. The DIPA compound or a pharmaceutical composition containing the DIPA compound can be appropriately topically administered to a subject, for example, as described herein. As used herein, the term "topical application" refers to delivery to the surface of the body that is in contact with air, which includes the skin, the surface of the anal-genital region, the transitional epithelial surface of the orbit, the lips, the tip of the nose, and the anus. Particularly preferred sites of application are the surfaces innervated by the trigeminal nerve and the cervical and sacral nerves, which include the scalp, facial skin, periorbital skin, and lips, as well as the surfaces of the neck, elbows, and knees, which are often associated with the itching of atopic eczema and psoriasis. Yet another preferred site is the scalp, which can be an inflammatory site for psoriasis and seborrheic dermatitis.

[0101] In one embodiment (e.g., use in a method of treatment, use in the manufacture of a medicament, method of treatment), the treatment is a treatment by topical administration. In one embodiment, the treatment is a treatment by topical administration to the skin. In one embodiment, the treatment is a treatment by topical administration to the facial skin. In one embodiment, the treatment is a treatment by topical administration to the periorbital skin, eyelid skin, malar skin, malar skin, frontal skin, or scalp. In one embodiment, the treatment is a treatment by topical administration to the skin surface of the orbit, frontal bone, or malar bone. In one embodiment, the treatment is a treatment by topical administration to the skin surface of the anus and / or the male or female genitalia. In one embodiment, the treatment is a treatment by topical administration to the skin over the flexure of the extremities, supraclavicular fossa, or sternocleidomastoid muscle.

[0102] Subject / patient. The subject / patient may be: a mammal, such as a marsupial (e.g., kangaroo, wombat), rodent (e.g., guinea pig, hamster, rat, mouse), murine (e.g., mouse), lagomorph (e.g., rabbit), bird (e.g., fowl), canine (e.g., dog), feline (e.g., cat), equine (e.g., horse), porcine (e.g., pig), ovine (e.g., sheep), bovine (e.g., cow), primate, anthropoid (e.g., monkey or ape), monkey (e.g., marmoset, baboon), ape (e.g., gorilla, chimpanzee, orangutan, langur), or human. In one preferred embodiment, the subject / patient is a human.

[0103] Formulation. The DIPA compounds can be administered alone as a liquid, for example, dissolved in physiological saline or water, but at least one DIPA compound described herein can be combined with one or more other pharmaceutically acceptable components well known to those skilled in the art (e.g., but not limited to, pharmaceutically acceptable carriers, diluents, excipients, adjuvants, fillers, buffers, preservatives, antioxidants, lubricants, stabilizers, solubilizers, surfactants (e.g., wetting agents), masking agents, and coloring agents) to prepare pharmaceutical formulations (e.g., compositions, preparations, drugs). The formulations may further contain other active drugs. Accordingly, the present discovery further provides a pharmaceutical composition as described above and a method for manufacturing the pharmaceutical composition as described above. When formulated as individual units (e.g., swabs, wipes, pads, towels, gels, lotions, creams, etc.), each unit contains a predetermined amount (dosage) of the compound.

[0104] As used herein, the term "pharmaceutically acceptable" with respect to a compound, component, material, composition, dosage form, etc. means that these are within the scope of sound medical judgment and are suitable for use in contact with the tissues of the subject (e.g., human) without excessive toxicity, irritation, allergic response, or other problems or complications, and are commensurate with a reasonable benefit / risk ratio. Each carrier, diluent, excipient, etc. must also be "acceptable" in the sense of being compatible with the other components of the formulation. Suitable carriers, diluents, excipients, etc. can be found in standard pharmaceutical texts, for example: Remington’s Pharmaceutical Sciences, 23rd edition, Mack Publishing Company, Easton, Pa., 2020; and Handbook of Pharmaceutical Excipients, 9th edition, 2018.

[0105] The formulation can be prepared by any method well-known in the pharmaceutical field. Such methods include the step of associating the compound with a carrier that constitutes one or more auxiliary components. Generally, the formulation is prepared by uniformly and closely associating the compound with a carrier (such as a liquid carrier, a finely divided solid carrier, etc.), and then, if necessary, shaping the product. The formulation may be in the form of a liquid, a solution (such as aqueous, non-aqueous), a suspension (such as aqueous, non-aqueous), an emulsion (such as oil-in-water type, water-in-oil type), an elixir, a syrup, a lozenge, a mouthwash, an eye drop, a tablet (including coated tablets), a granule, a powder, a troche, an incense tablet, a capsule (including hard gelatin capsules and soft gelatin capsules), a cachet, a pill, an ampoule, a bolus, a suppository, a pessary, a tincture, a gel, a paste, an ointment, a cream, a lotion, an oil, a foam, a spray, a mist, or an aerosol. Further, the DIPA compound can also be used as an adjuvant in pharmaceutical formulations or cosmetic formulations.

[0106] Dosage. One skilled in the art will understand that the appropriate dosage of the DIPA compound and the composition containing the DIPA compound may vary from patient to patient. Determining the optimal dosage will generally involve balancing the level of therapeutic benefit against any risks or adverse side effects. The dosage level selected will depend on various factors (such as, but not limited to, the activity of the particular DIPA compound, the route of administration, the time of administration, the duration of treatment, other drugs, compounds, and / or materials co-administered, the severity of the disease, and the patient's race, gender, age, weight, condition, general health status, and past medical history). The amount and route of administration of the DIPA compound will ultimately be left to the discretion of the physician, pharmacist, veterinarian, or clinician, but generally, the dosage will be selected to obtain a local concentration at the site of action that achieves the desired effect without causing significant harmful or toxic side effects.

[0107] Administration can be carried out once, continuously or intermittently (e.g., by divided administration at appropriate intervals) throughout the course of treatment. The most effective means of administration and method for determining dosage will be well known to those skilled in the art and will vary with the formulation used for treatment, the purpose of treatment, the target cell(s) being treated, and the subject being treated. Single or multiple administrations can be carried out using the dosage levels and patterns of administration selected by the treating physician, veterinarian, or clinician.

[0108] Targets of delivery. Epithelial cells cover the surfaces of organs and cavities throughout the body. When there are two or more layers of epithelium, it is called stratified epithelium. Historically, stratified epithelium has been divided into two major categories (keratinized stratified epithelium and non-keratinized stratified epithelium). Keratinized epithelium (e.g., the epidermis of the skin) has an outer layer [stratum corneum] composed of dead cells made of tough, water-impermeable keratin proteins. In contrast, non-keratinized stratified epithelium is located in the "soft tissues" of the body (e.g., the inner walls of the nasal and laryngeal cavities and the inner walls of the esophageal surface). Keratinized tissues are more resistant to damage than non-keratinized tissues. The non-keratinized epithelial surface must be kept moist by glandular (serous and mucinous) secretions to avoid drying.

[0109] The stratum corneum (the keratinized layer of dead cells) is a significant barrier to the penetration of drugs to the nerve receptor fields embedded in the epithelial tissue beneath the keratin. The thickness of the barrier and the layer of dead cells vary. The heels and palms have the most layers of dead cells (about 82 layers). The genitalia (e.g., the penile shaft) and eyelids have fewer layers (4 - 8 layers). The skin of the face has about 10 - 14 layers, the skin of the trunk has about 12 - 16 layers. The limbs have slightly more layers (more than about 15 layers). Dermatitis frequently occurs on the limbs (e.g., the flexures of the elbows and knees in atopic dermatitis) and on the trunk and scalp in the case of psoriasis. Hand eczema often occurs on the hands (contact dermatitis). Urticaria can occur throughout the body, and wheals appear on the trunk, neck, and buttocks.

[0110] However, the stratum corneum is not a hard wall made of bricks and mortar but has water pores like limestone, through which water-soluble molecules can pass between and through cells. The intracellular water transport channels on keratinocytes are called aquaporins (Patel R et al. Aquaporins in the Skin. Adv Exp Med Biol. 2017, 969:173-191). The active ingredient must reach the nerve endings located in the basal layer (stratum basale) of the skin. The surprising discovery herein is the ability of the DIPA compound to suppress paresthesia when applied as an aqueous solution on a wipe. A possible explanation is that DIPA passes between cells through water channels without passing through the cells. Current topical anti-nociceptive (analgesic) compounds effective against the sensory discomfort of keratinized skin are high concentrations of l-menthol (36% alcohol solution) or topical anesthetic gels. However, these two types of topical therapeutics have problems of an oily feeling and irritation, as well as problems of allergic reactions.

[0111] The target of topical delivery of the DIPA compound is located at the nerve endings in the receptive fields of peripheral sensory nerves and cranial sensory nerves. In the case of the face, the receptive fields of the ophthalmic and maxillary branches of the trigeminal nerve are the preferred target sites.

[0112] Figure 2 is a diagram of the human face showing the innervation of the zygomatic skin by the zygomaticofacial nerve (ZFN) and infraorbital nerve (ION). The receptive fields of these nerve endings were used to test compounds applied to the zygomatic skin. The figure is cited from: Hwang et al. [Cutaneous innervation of the lower eyelid. J. Craniofacial Surgery 19:1675-1677, 2008].

[0113] In these studies, the main examination site was the skin of the zygomatic bone (cheekbone). Alternatively, when the coolant is used for vulvar itching, it can also be applied as a spray to the skin of the upper labia. The coolant can be applied directly to the site of injury and / or inflammation. The second site is the skin on the frontal bone and the scalp, but a high concentration of coolant is required for these sites. In practice, the coolant can be applied by spray or (for example, using a cotton swab or pad, or in the form of a gel, lotion, cream, or ointment) to the skin of the eye socket, the skin of the zygomatic bone (cheekbone), or the skin between the zygomatic bone under the eye and the nose. At this site, the receptive fields are in the lower divisions of the trigeminal nerve, namely, the zygomaticofacial nerve of the maxillary nerve (V2) and the supraorbital and supratrochlear branches of the frontal nerve (V1).

[0114] Delivery method. The delivery of the DIPA compound can be carried out using a cotton swab, a wet wipe, or as an aerosolized mist in a solid or semi-solid vehicle (e.g., cream or ointment) dissolved in a liquid vehicle (e.g., water or physiological saline, or a solution, hydrogel, lotion). A gel is a semi-solid jelly-like preparation of various viscosities. A gel forms a solid three-dimensional network that spreads throughout the volume of the liquid medium. A gel is made using a gelling agent that crosslinks or binds to the liquid phase. Examples of gelling agents are as follows: cellulose derivatives [methylcellulose, carboxymethylcellulose, hydroxypropylcellulose]; carbomers [Carbopol® 910, Carbopol® 941]; poloxamers [Pluronic®, Tween]; carbomer polymers, as well as natural polymers (e.g., tragacanth, acacia, gelatin, sodium alginate, alginic acid, and xanthan gum). A single-phase system is a gelling agent and an active ingredient that is dissolved [in water] without visible particles and appears transparent. A topical gel optimally liquefies upon contact with the skin or mucosa. The compound of formula 1 is soluble in water and forms a single-phase system at therapeutic concentrations, making it attractive for delivery as a gel. Methods for formulating topical gels are known in the art and are described in detail on such sites as Lubrizol.com [a company that manufactures raw materials for cosmetics, personal care, skin care, and eye care]. The preferred concentration of the DIPA compound is 0.01 - 2.0% wt / vol. Unless otherwise stated, wt / vol is measured in g / cm3 or g / mL units, thus 0.01% wt / vol is obtained from 0.1 mg (0.0001 g) of the DIPA compound in 1 cm3 of the composition, and 2% wt / vol is obtained from 20 mg (0.02 g) of the DIPA compound in 1 cm3 of the composition.

[0115] For liquid vehicles, the preferred single delivery volume is 0.02 - 0.15 mL. For example, when delivered as a lotion or wipe, such an amount results in little residual liquid at the delivery site because the liquid is absorbed. For liquid vehicles, the preferred concentration of the DIPA compound is in the range of 0.5 - 30 mg / mL. For the orbital area, the preferred concentration is 1 - 5 mg / mL. For the submalar and suborbital skin, the preferred concentration is 5 - 10 mg / mL. For the forehead skin and scalp, the preferred concentration is 10 - 30 mg / mL. The preferred amount of the DIPA compound delivered to the application site is 0.01 - 5 mg, for example, 0.1 - 5 mg.

[0116] The application of the DIPA compound to the target skin can be carried out using a pre-moistened wipe, which is well known in personal care products, for example, for wiping the skin of a baby after diaper change or for removing facial makeup (e.g., Pond's 6-inch × 8-inch (15 cm × 20 cm) Clean Sweep Cleansing and Makeup Remover Towel). Usually, these wipes are packaged as disposable sealed units or in dispensers for multiple units. In the case of a single unit, a suitable packaging material is relatively vapor impermeable to prevent the wipe from drying and is capable of forming a "peelable" seal. Examples of wipe materials suitable for practicing the present discovery include the following: polyamide (20% nylon) polyester, rayon (70%) polyester (30%) formed cloth, polypropylene non-woven fabric, polyethylene terephthalate (PET), polyester polypropylene blend, cotton, viscose, rayon, or microfiber (synthetic fiber measuring less than 1 denier or 1 decitex).

[0117] Alternatively, the solution containing the DIPA compound can be supplied in a reservoir bottle with an individual applicator or as a pre-packaged individual unit. For example, the Puritan 803-PCL applicator is an applicator with an ideal cotton tip attached to a 3-inch (about 7.5 cm) polystyrene rod for delivering the DIPA compound to the skin around the eye socket. Examples of such applicators that can be individually packaged are: SwabDose (trademark) manufactured by Unicep Corporation (1702 Industrial Drive, Sandpoint, Idaho, USA) and Pro-Swabs manufactured by American Empire Manufacuring (3828 Hawthorne Court, Waukegan, Illinois, USA). Each applicator tip is saturated by immersing the absorbent material of the tip (e.g., 40 - 100 mg of cotton) in 0.1 - 1.5 mL of an aqueous solution of the DIPA compound and packaged in an individual container.

[0118] When applying to the face, the individual is instructed to gently apply or spray the cream, lotion, gel, or wet wipe onto the target facial skin or other skin surface(s) with eyes closed. The application instructions may include teaching the individual to repeat the application or "top up" so that sufficient composition is delivered to the target. Once the subject has learned what is expected, the dosage can be adjusted as needed (e.g., by lightly applying to the inner or outer edges of the eye socket) to obtain the desired effect. It has been observed that after one or two trials, the subject quickly learns how to effectively apply the coolant.

[0119] When applying to the anal-genital skin or other very sensitive surfaces, the DIPA compound may be rubbed or sprayed, for example, in an amount of about 0.15 mL per unit. Alternatively, a dropper can be used with a wipe made of a soft material (e.g., 100% cotton).

[0120] Mechanism of action. Sensory neurons express receptors and ion channels on their membranes to detect various stimuli. The stimuli are converted into electrical signals by the receptors and transmitted to the central nervous system (spinal cord or brain) to become sensations. These sensory receptors are transducers, and the process is called transduction.

[0121] The locally applied DIPA compound reduces skin discomfort by causing a "dynamic coldness" sensation at the application site. One feels a strong sense of refreshment as if suddenly a fresh and cool breeze blows on the skin (e.g., the face) or cold water splashes on the skin. This effect by DIPA-1-7 is particularly strong. This conversion process, the mechanism of the receptor, and the importance of dynamic cooling for the anti-itching effect are further described herein and are called "cool feeling".

[0122] Neurophysiology: Small myelinated fibers (Aδ) and unmyelinated fibers (C fibers) increase their afferent firing frequency when skin temperature drops, for example, from 25 °C to 10 °C. These nerve signals detecting heat extraction are transmitted to the central nervous system, generating a conscious perception of coldness and chill. When skin temperature rises from 35 °C to 40 °C, the firing frequency of C fibers increases, and these fibers transmit warmth [Hutchinson et al. Quantitative analysis of orofacial thermoreceptive neurons in the superficial medullary dorsal horn of the rat. J. Neurophysiol. 77, 3252 - 66, 1997]. The receptive mechanisms and "cable lines" for coldness / chill and warmth are distinct and clearly distinguishable, but they inhibit each other in the brain and probably also peripherally. Sensory receptors are modality-specific and do not respond to mechanical stimuli. At the molecular level, the target binding site of the coolant is thought to be located on the TRP ion channel receptor that depolarizes in response to a temperature decrease. Heat extraction reduces the discharge threshold of the receptor, and the promoted depolarization initiates an axonal response that generates a nerve signal.

[0123] The central responses of these cold-sensitive neurons have been recorded from the superficial dorsal horn of the spinal cord of rats in response to innocuous temperature stimuli on the face and tongue of rats [Hutchinson et al., 1997]. A step change of -Δ5°C stimulates both cells with static firing frequency and cells with dynamic properties [Davies et al. Sensory processing in a thermal afferent pathway. J. Neurophysiol. 53:429-434, 1985]. Similar studies on cats and humans have shown that a step decrease in temperature (as little as Δ0.5°C / sec) (dynamic change) was readily detectable by neuronal and psychophysical measurements [Davies et al. Facial sensitivity to rates of temperature change: neurophysiological and psychophysical evidence from cats and humans. J. Physiol. 344:161-175, 1983]. From studies of the spike pattern (impulses / sec) of nerve firing, it was clear that the dynamic rather than static firing response to temperature change is the most powerful stimulus for producing the sensation of coldness / cold. That is, the brain "sees" -Δ°C / t rather than absolute °C. Thus, a coolant that stimulates -Δ°C / t during nerve firing produces "dynamic cooling".

[0124] Dynamic cooling for treating cutaneous paresthesia and pruritus. Due to the strong sensory effect, dynamic cooling (static cooling / cold) is essential. For example, when driving a car tired, turning on the air conditioner and blowing wind on the face will relieve fatigue [dynamic cooling]. However, just turning on the air conditioner to lower the ambient temperature and cool the interior of the car (static cooling) will not make much difference. The advantages of local sensory therapy are demonstrated by the case studies described herein.

[0125] Receptor mechanism: There is general agreement that "TRP-" ion channel receptors (e.g., A1, M8, and V1-4) are the main elements of physiological temperature detection. The TRPM8 receptor responds to sensory / cooling agents (e.g., menthol and icilin) [McKemy et al. Identification of a cold receptor reveals a general role for TRP channels in thermosensation, Nature, 416, 52-58, 2002]. TRPM8 is a protein with 1104 amino acid residues and has six transmembrane domains. When this receptor is activated by lowering the ambient temperature, the pore of the transmembrane loop opens and non-specific cations enter the cell. Depolarization of the TRPM8 receptor on sensory neurons transmits signals to the spinal cord or brain mainly via Aδ (and some C) fibers.

[0126] This concept regarding the role of TRPM8 in sensory physiology may be valid for the physical changes in temperature, but the interpretation of the sensory effects of chemical substances (e.g., menthol and icilin) is more complex. Menthol stimulates not only TRPM8 in vitro but also TRPV3, a receptor related to warmth and glycine-mediated transmission, as well as other TRP receptors [Macpherson et al. More than cool: promiscuous relationships of menthol and other sensory compounds. Mol Cell Neurosci 32:335 - 343, 2006; Sherkheli et al., Supercooling agent icilin blocks a warmth-sensing ion channel TRPV3, Scientific World Journal, 2012; Cho et al. TRPA1-like channels enhance glycinergic transmission in medullary dorsal horn neurons. J Neurochem 122:691 - 701, 2012]. Thus, menthol and icilin are polyvalent "nonspecific" coolants, and their sensory effects may not be related to any specific receptor protein. An experimental reagent specific and selective for TRPM8 would be beneficial for experiments.

[0127] The applicant screened a large database of coolants and surprisingly found that only DIPA compounds produce extremely potent dynamic cooling on the skin. DIPA-1-8 and DIPA-1-9 produce strong cooling, and their effects are persistent, but there is no such amazing cooling as DIPA-1-6 and DIPA-1-7. Other types of coolants (e.g., p-menthane carboxamide) generally have a short duration of action and little dynamic coldness and thus are not very suitable for the uses contemplated herein. Thus, DIPA compounds are ideal selective reagents for TRPM8 function, in contrast to menthol, p-menthane carboxamide, and icilin.

[0128] Based on what is known about the physiological function of TRPM8, it is logical to consider that DIPA-1-7, DIPA-1-8, and DIPA-1-9 bind to the allosteric site of a voltage-dependent ion channel receptor located at the nerve terminals sensitive to a physical decrease in temperature. This binding event promotes the depolarization of neurons in response to the cooling / cold signal, and the action potential is transmitted to the central nervous system via Aδ fibers and C fibers. When the nerve terminals are located in the facial skin, in animals, signals can be recorded from the dorsal surface of the trigeminal nucleus in the brainstem, as in the study by Hutchison et al. (cited above). Subsequently, the rostral transmission and integration of the signals result in the perception of coldness / cold and a local association with the site of stimulation.

[0129] When examining the structure-activity relationship (SAR) of DIPA compounds, note that cooling is observed when R1 = R2 = isopropyl and R3 = C6 - C9. Using R3 = n-octyl (C8), strong cooling over a long period can be obtained. Using R3 = n-nonyl (C9), refreshing cooling over a long period can be obtained. A special attribute of the n-nonyl analog is that there is no burning / stinging sensation even at a high concentration of 5% in water. In contrast, sec-butyl-containing analogs are not as powerful. As shown in the studies described herein, the difference between di-sec-butyl compounds and di-iso-propyl compounds is also seen in animal experiments regarding the shivering behavior, which is an indicator of the cooling effect in rats. Animals covered with fur shake like dogs because the triggering event is a cold and wet stimulus. Shivering is suppressed by heat. The shivering behavior assay of wet dogs exhibits rapid alternating contractions of the extensor and flexor muscles around the spinal axis and can be easily observed and counted. All animals covered with fur and animals with feathers shake like wet dogs (when wet and cold) [Dickerson et al., Wet mammals shake at tuned frequencies to dry. J. Royal Society, Interface 9, 3208 - 3218, 2012; Ortega-Jimenez, V.M. et al. Aerial shaking performance of wet Anna’s hummingbirds. J. Royal Society, Interface 9, 1093 - 9, 2012; Wei, Pharmacological aspects of shaking behavior produced by TRH, AG-3-5, and morphine withdrawal, Federation Proc. 40:1491 - 1496, 1981].

[0130] "The shivering of wet dogs" has been studied in detail in animals. Rats can shake their heads and upper bodies, or the shivering can affect the whole body and be intense enough for the animal to lose its balance. DIPA-1-7 and DIPA-1-8 induce a severe type of shivering. The purpose or survival value of shivering for furry and feathered organisms is to remove water droplets trapped on or near the skin. Removing the water droplets reduces the organism's need to expend energy to remove water by evaporation. In humans, a behavior equivalent to possible shivering is shuddering (a state caused by the systemic sensation of cold). Human subjects recovering from extreme hypothermia due to anesthesia exhibit severe shivering (a state called postanesthetic shivering). Human subjects can also perform "wet shivering" by deliberately engaging in it when getting out of a swimming pool.

[0131] Isirin (1-[2-hydroxy]-4-[3-nitrophenyl]-1,2,3,6-tetrahydropyrimidin-2-one) induces severe tremors in rats [Wei. Chemical stimulants of shaking behaviour. J. Pharmacy and Pharmacology 28:722-724, 1976]. Surprisingly, two potent p-menthane carboxamide cooling agents [(R)-2-[((1R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-propionic acid ethyl ester, and [((1R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-acetic acid isopropyl ester] that have an EC50 value similar to that of isirin at the TRPM8 receptor do not cause tremors (when 50 mg / kg is injected subcutaneously into male rats and observed for 1 hour). Activation of isirin at the TRPM8 receptor is abolished by the G805A mutation in the second to third transmembrane loop, but the effect of menthol is not affected. DIPA-1-6, DIPA-1-7, and DIPA-1-8 may also have specific binding and activation sites on the TRPM8 receptor that are not shared by menthol or p-menthane carboxamide. Studies by Wei and Kuhn have shown that DIPA-1-6 and DIPA-1-7 are still active on the TRPM8 receptor with the G805A mutation.

[0132] Watson et al., 1978 [New compounds with the menthol cooling effect. J. Soc. Cosmet. Chem. 29: 185-200, 1978] showed that a polar oxygen moiety capable of hydrogen bonding is an essential structural requirement for biological activity. Huckel molecular orbital calculations (using Molecular Modelling Pro v6.0.3, ChemSW Inc, Fairfield, California 94534, USA) for the isopropyl analog and the sec-butyl analog supported a slightly higher partial negative charge (0.007e) on the oxygen of the sec-butyl entity, suggesting that the sec-butyl substituent increases the affinity of the oxygen for the hydrogen bonding site of the receptor. Thus, isopropyl, which has a more "loose" affinity, prefers to associate and dissociate more rapidly with the receptor, resulting in the dynamic expression and disappearance responses of the receptor. This rapid interaction with the binding site promotes a more "dynamic" and potent cooling stimulus, resulting in a phenomenon known as shivering.

[0133] TRPM8, TRPA1, and TRPV1 Receptor Assays TRPM8 is a cation channel activated by cold temperatures and cooling compounds (e.g., menthol and icilin). In this application, the in vitro effects of test compounds on the cloned hTRPM8 channel (encoded by the human TRPM8 gene and expressed in CHO cells) were evaluated using a Fluo-8 calcium kit and a fluorescence imaging plate reader (FLIPR TETRA (trademark)) instrument. To examine the specificity of the test compounds, further tests were conducted on the TRPV1 channel (human TRPV1 gene expressed in HEK293 cells) and the TRPA1 channel (human TRPA1 gene expressed in CHO cells). The assays were performed at ChanTest Corporation, 14656 Neo Parkway, Cleveland, OH 44128, USA. Cells grown in culture were seeded overnight at a density of approximately 30,000 cells / well, loaded with 2 μM Fura-2 (Molecular Probes, Leiden, Netherlands) for approximately 1 hour, and then placed on a glass coverslip. The test solution was added with a micropipette placed near the cells. Using excitation wavelengths of 340 and 380 nm and an emission wavelength of 520 nm, the luminescence intensity from the cells was measured every 4 or 5 seconds for 90 seconds. The fluorescence emission intensity ratio (R, within individual cells) at 340 nm / 380 nm excitation was recorded using FlexStation and the ImageMaster suite of software (PTI, South Brunswick, NJ). Samples were tested three times at each concentration, and the mean values were analyzed by non-linear regression using a point sigmoid function approximation to obtain the estimated EC50 (median effective concentration) (GraphPad Prism software, La Jolla, CA). The in vitro assays provide information on the relative potency and selectivity at the receptor. DIPA is selective for TRPM8 and does not activate TRPV1 or TRPA1.

[0134] Selection of Active Ingredients. Ideally, a pharmaceutical active ingredient (API) formulated for delivery to keratinized skin should be stable, non-toxic, long-acting, and potent enough to activate the mechanism that results in the anti-infringement receptive effect. The API should be miscible in the composition so that the formulation can maintain a constant concentration during production. The final product must meet the standards of purity, cleanliness, and sterility. For the purpose of formulation, the API can be liquid under standard conditions of standard and pressure (STP), which is uniformly dissolved in an aqueous solution of neutral pH and / or isotonicity. The sterility of the final product can be optimally achieved by using filtration with purified reagents and micropore filters, heating, or radiation irradiation. Standard excipients (e.g., emulsifiers, isotonic saline, solvents, stabilizers, and preservatives) can be added to optimize the formulation, but important components should preferably be soluble in an aqueous medium (e.g., purified water or standard dermatological solvents).

[0135] For a particular individual, the perceived sensation is a function of the particular coolant, dosage, vehicle used to carry the coolant, method of topical delivery, and the nature of the target surface. The applicant has screened compounds (e.g., isilin and p-menthane carboxamide) on facial skin (Wei. Sensory / cooling agents for skin discomfort. Journal Skin Barrier Research 14:5-12, 2012). The research in this specification identifies DIPA compounds with desirable properties of an ideal API for paresthesia and itching. In summary, the design concept for selecting a particular DIPA is as follows: ● Definition of the rationale for using the "dynamic cold" sensation on the skin to reduce sensory discomfort, and an explanation of the neurophysiology and receptor mechanism of this action. This sensory effect is exceptional and is only seen in certain DIPA compounds. ● Devise a method of delivering the ideal compound to its receptive field by taking advantage of the water solubility of these analogs, thereby reducing the need for excipients. ●Finding ideal compounds through experiments: DIPA-1-7, DIPA-1-8, and DIPA-1-9 are water-soluble (a clear solution of up to 20 mg / mL can be obtained in distilled water), stable to heat, and can exhibit a "strong coldness" sensation for up to 5 - 7 hours at a concentration of 1 - 10 mg / mL. Repeated application does not cause tachyphylaxis. DIPA-1-7 has a higher likelihood of producing freezing cold compared to DIPA-1-9. ●Define the receptor targets of these compounds in vitro and conduct experiments to show the selectivity of the selected DIPA. ●Define an animal model (e.g., "shivering of a wet dog") that can explain the "dynamic coldness" property and enable further research on the mechanism of action and the selective differentiation of various analogs. ●Conduct tests in human volunteers to show the effectiveness of DIPA compounds in reducing skin paresthesia caused by various skin diseases. ●Show that DIPA compounds (especially DIPA-1-7) are effective in reducing skin paresthesia, thereby enabling the treatment of skin diseases for use as anti-nociceptive or anti-itch drugs.

[0136] Examples of the uses of DIPA compounds When applied to keratinized skin, DIPA compounds can obtain cooling that mimics heat extraction without a change in tissue temperature. These compounds penetrate the skin barrier, reach the nerve endings in the epidermis and dermis, enter the systemic circulation, and exert a cooling effect. These effects can be obtained in small amounts (e.g., 0.1 - 0.5 mL) when applied at a concentration of 1 - 20 mg / mL, or 0.1 - 2% wt / vol. The onset of the effect is rapid, within less than 5 minutes, and the cold sensation is strong, refreshing, and powerful. Compounds showing similar biological activity on the skin are not currently known or used for cosmetic or therapeutic purposes. Many new uses are possible using DIPA with such exceptional properties. This is demonstrated by the use of DIPA in various skin diseases.

[0137] Dermatitis and pruritus: When DIPA is topically applied, a cooling sensation occurs. In cases of paresthesia and itching, these analogs exert an anti-itching effect and other anti-nociceptive effects. As shown in the case studies described herein, various formulations strongly suppressed itching and discomfort. The most recent and surprising event was the discovery that DIPA acts on intact skin to stop itching. This is seen in patients with urticaria, cholestatic pruritus, and scalp pruritus. DIPA-1-7 was also effective in refractory cases of miliaria rubra (heat rash) and prurigo nodularis (a type of chronic atopic dermatitis). There are no known topical therapeutic agents with immediate efficacy for these conditions. Data are also shown that DIPA is effective for blepharitis, conjunctivitis, and eye pain. On the anogenital surface, DIPA is effective for lichen sclerosus and vulvar pruritus. The reduction of itching and paresthesia usually occurs within 5 minutes after DIPA administration and lasts for several hours, and this duration is clinically important.

[0138] Topical therapeutic agents that reduce paresthesia and itching of the skin have many uses for patients with skin diseases (about 80% complain of itching and skin irritation) including: a) Relief of irritation, itching, and pain due to dermatitis (atopic dermatitis, contact dermatitis, and irritant dermatitis, various forms of eczema); b) Itching and discomfort due to skin infections, insect bites, sunburn, photodynamic treatment of the skin (e.g., actinic keratosis, basal cell carcinoma), lichen sclerosus; c) Pruritus due to xerosis [especially itching of dry skin in the elderly], psoriasis, or seborrheic dermatitis; d) Anal pruritus, discomfort of hemorrhoids, pain due to anal fissure, pain or itching due to anal fistula, pain due to hemorrhoidectomy, vulvitis, anogenital dermatitis, and discomfort due to various local causes (e.g., incontinence, diaper rash, miliaria rubra, and vulvitis); e) Pain due to burns, trauma, diseases, anoxia, or irritated skin (e.g., laser surgery, diabetic ulcer, sunburn, radiation-induced skin damage), and pain due to wound debridement and procedures related to wound healing; f) Itching of the lips due to stomatitis, cheilitis, herpes labialis, or gingivitis; g) Pruritus and pain in the vulvar area (e.g., candidal or idiopathic, such as vulvar vestibulitis and vulvodynia), dyspareunia, ano-genital infections (e.g., warts and sexually transmitted infections), fungal infections, viral skin infections (especially in immunocompromised patients); h) Conjunctivitis, blepharitis, irritation of the ocular surface, pain due to trauma and corneal abrasion, and pain due to ophthalmic surgery.

[0139] Particularly interesting is the use of DIPA-1-7 and DIPA-1-8 for itching of the scalp such as seborrheic dermatitis and psoriasis. These endpoints represent unmet medical needs. DIPA-1-7 can also be used to refresh the skin before applying cosmetics to the skin or after removing cosmetics, reduce the irritating effect of benzoyl peroxide in acne treatment, and reduce sebum secretion and the appearance of "oily" skin.

[0140] Break the vicious cycle of itching and scratching. Itching is a sensation that triggers the desire or reflex to scratch. Itching can be very intense and cause compulsive behavior. For example, individuals have been observed to scratch their ankles until they bleed due to itching caused by insect bites (mosquitoes and flies). In the case of animals covered with fur, scratching can have a survival value as it removes parasites and insects attached to the skin, but in humans, excessive scratching worsens skin damage due to skin diseases. Scratching damages the skin, and the wound induces further itching and scratching, and the phenomenon is called the "itch-scratch vicious cycle". MacDonald et al. have proposed a mechanism by which the itch-scratch vicious cycle worsens tissue damage (Acta Dermato-Venereologica 97(8):1010, 2017). He stated that double-stranded RNA released from damaged keratinocytes stimulates the TOLL-3 receptor to generate more cytokines and chemokines, thereby enhancing and prolonging inflammation.

[0141] Accordingly, anti-itch molecules may not only provide symptomatic relief, but may also have a more subtle disease-modifying therapeutic effect in disorders where itching is local and the itch-scratch vicious cycle adversely affects the pathology of excoriation and lichenification (e.g., atopic dermatitis). Due to scratching, the irritated skin becomes thickened, chronically inflamed and brittle, and is further prone to scratching, friction and breakage. The ability to interrupt scratching is not limited to atopic dermatitis, but can also be applied to other skin diseases (e.g., seborrheic dermatitis, acne, or acneiform eruptions). In this specification, for example, acne lesions are inflammatory diseases of the sebaceous glands of the skin, and subjects constantly pick and squeeze the lesions. Mechanical damage to inflamed skin exacerbates the underlying tissue response. If tissue manipulation can be interrupted, the lesions are given more time to heal faster.

[0142] Itching interferes with sleep, and atopic dermatitis patients will scratch their bodies violently even during sleep. An effective therapeutic agent should prevent itching and act long enough for the subject to fall asleep within a few minutes after application. The subject should be instructed to apply the therapeutic agent after washing the face, use it as needed, and apply it to itchy areas all night before going to bed. This is particularly important for children. Because the urge to scratch is instinctive and automatic, but the skin will also be damaged.

[0143] Pharmaceutical adjuvants: In pharmaceuticals or cosmetics, the term "adjuvant" is an additional substance, treatment, or procedure used to enhance the effectiveness or safety of the main substance, treatment, or procedure, or to facilitate its performance. DIPA compounds reduce the sensory discomfort of the skin, have an anti-nociceptive effect, and are active in less than 1 minute after application. They are ideal adjuvants for pharmaceuticals and cosmetics applied to the skin.

[0144] An adjuvant (e.g., DIPA-1-7) can be used to enhance the “apparent” effectiveness of another active ingredient, thereby improving patient satisfaction and compliance with the dosing schedule. For example, within a few minutes after application, itching stops due to about 0.5 - 2% DIPA-1-7. When used in combination with an anti-inflammatory steroid, the preparation may be more desirable than the anti-inflammatory steroid alone, which takes time to act. Anti-inflammatory steroids (e.g., hydrocortisone, triamcinolone, and clobetasol) are used for the sensory discomfort of the skin in disorders (e.g., insect bites, contact dermatitis, atopic eczema, and psoriasis). In addition to helping to stop itching, the presence of DIPA-1-7 as an adjuvant can help reduce the dosage or frequency of application of the active ingredient and still achieve an equivalent therapeutic effect. This advantage of the adjuvant would be particularly beneficial in the use of skin steroids due to the well-known desirable effects of collagen degradation, tissue thinning, and increased susceptibility to infection. Adjuvants that reduce the dosage or enhance the effectiveness of the active ingredient have value. Other major anti-itch drugs are aluminum acetate and strontium chloride or strontium nitrate.

[0145] In the case of skin disorders, the compositions of this discovery can also be used as adjuvants for treatments (e.g., phototherapy, laser therapy, cryotherapy, or ultraviolet therapy of the skin). Pharmaceuticals that can be used in combination with, or in sequence with, the adjuvant DIPA compound include: anti-inflammatory steroid drugs, anti-inflammatory analgesics, antihistamines, sympathomimetic amine vasoconstrictors, local anesthetics, antibiotics, anti-acne drugs, topical retinoids, drugs for the treatment of genital warts and skin cancer, drugs for the treatment of wrinkles and aging skin, drugs for the treatment of hemorrhoids, drugs for itching of the vulva, drugs that stimulate hirsutism, skin moisturizers, and drugs for exfoliation.

[0146] Examples of steroid anti-inflammatory drugs include the following: hydrocortisone, clobetasol, clobetasol propionate, halobetasol, prednisolone, dexamethasone, triamcinolone acetonide, fluocinonide acetonide, fluocinide, hydrocortisone acetate, prednisolone acetate, methylprednisolone, dexamethasone acetate, betamethasone, betamethasone valerate, flumethasone, fluticasone, fluocinolone, beclomethasone dipropionate, etc. Examples of anti-inflammatory analgesics include the following: methyl salicylate, salicylic acid monoglycol, aspirin, indomethacin, diclofenac, ibuprofen, ketoprofen, naproxen, pranoprofen, fenoprofen, sulindac, fenclofenac, clidanac, flurbiprofen, fentiazac, bufexamac, piroxicam, pentazocine, etc. Examples of antihistamines include the following: azelastine hydrochloride, diphenhydramine hydrochloride, diphenhydramine salicylate, diphenhydramine, chlorpheniramine maleate, promethazine hydrochloride, etc. Examples of sympathomimetic amine vasoconstrictors include phenylephrine hydrochloride, oxymetazoline, naphazoline, and other imidazoline receptor agonists used for relieving nasal congestion and for the relief of hyperemia and vasodilation of the ocular surface. Examples of the components of skin moisturizers include three categories: humectants, emollients, and preservatives. Humectants (e.g., urea, glycerin, and alpha-hydroxy acids) help absorb moisture in the air and retain it on the skin. Emollients (e.g., lanolin, mineral oil, and petrolatum) have the effect of filling the gaps between skin cells, giving the skin moisture, and making it smooth. Preservatives help prevent the growth of bacteria in humectants. Other components that humectants may contain include vitamins, minerals, plant extracts, and fragrances. An example of a drug for hirsutism is bimatoprost.

[0147] Study 1 Toxicity studies. Preliminary toxicological studies were conducted on DIPA1-7. No mutagenicity was observed in the Ames test (TA98 and TA100 strains, with or without liver activation) (the test was performed by Apredica, Watertown, Massachusetts, USA). DIPA-1-7 dissolved in 3% ethanol / 97% 1,2-propanediol, or the solvent alone, was administered orally to male rats at 20 mg / kg for 7 days (n = 10 per group). On the 8th day, the animals were euthanized with sodium pentobarbital, and the major organs (body, heart, liver, lung, kidney, testis, brain) were excised and weighed. Heart tissue (ventricles and heart valves) and liver samples were stained with hematoxylin and eosin and examined histologically. There were no significant differences in body weight or organ weights between the two groups, and histological examinations of the heart and liver were normal.

[0148] Study 2 Tissue temperature. The compounds of this discovery cooled but did not change the temperature of the tissue. After applying DIPA-1-7 (with a wipe at a concentration of 20 mg / mL in distilled water) to the forehead skin of subjects (N = 5), the average forehead skin temperature was measured. The results are summarized in Table 5. The subjects noticed that the cooling effect of DIPA-1-7 on the skin lasted for 30 - 45 minutes, but there was no effect on skin temperature. [Table 5]

[0149] Study 3 The effect of the compound on the facial skin. When the test compound is applied to the skin, the resulting sensation can be characterized. The quality of the sensation produced by each individual compound works to advantage for specific properties that are clearly distinguishable. The induced sensations, their descriptors, and the proposed mechanisms of action are summarized in Table 6. For any compound, there may be overlap in its activities, but usually, one compound occupies only one or two categories of effects. For example, isilin is only coldness, and there is very little "chill". DIPA-1-6 and DIPA-1-7 are excellent at producing a pleasant and strong "dynamic coldness". DIPA-1-8 and DIPA-1-9 are powerful cold sensation generators.

Table 6

[0150] In the studies described herein, the sensation of coldness / chill was evaluated as 0, 1, 2, or 3; 0 is no change; 1 is slight coldness, or chill; 2 is a clear sign of coldness or chill; 3 is evaluated as strong cooling or chill. The sensations were recorded at 5- to 15-minute intervals until at least two consecutive zeros were obtained. The onset of drug action is considered the time until the intensity of coldness reaches 2 units.

[0151] The duration of the sensory effect is defined as the end time minus the start time. The end of drug action is defined as the time when the intensity of coldness drops below 2 after exceeding 2 units. An inactive compound is defined as one where cooling does not exceed 2 units for more than 5 minutes after application. For compounds that act for more than 2 hours, the sensation of coldness / chill can vary due to environmental variables (e.g., sunlight, ventilation, activity, and "reservoir effects"), so the offset endpoint can be, in some cases, unstable. For example, DIPA-1-8 and 2-8 are exceptionally long-acting on the skin.

[0152] The effects of the test compounds on the facial skin were determined. The compounds were tested on the skin of the cheekbones (zygomatic bones). A cotton gauze (0.4 g, rectangular, 50 mm x 60 mm, CS-being, Daisan Men Industry, Japan) was used to apply the test compounds. A test compound with a concentration of 20 mg / mL in distilled water was used. The onset and duration of the sensory effects were measured with a stopwatch. The degree of "dynamic coldness" was evaluated from 0 to +++ with intermediate steps being + and ++. The anti-fatigue effect was present only when there was sufficient "dynamic coldness". The results are summarized in Table 7.

Table 7

[0153] 3-1 and 3-2 were also tested respectively and were found to be inactive on the skin around the eye sockets and on the zygomatic bone / forehead.

[0154] For further comparison, newly synthesized "mixed" 1-isopropyl-sec-butyl-phosphorylalkanes (3,4-6, 3,4-7, 3,4-8, and 3,4-9) were tested on the zygomatic skin (Figure 2). Since the amounts of these analogs were limited, the test procedure was changed. To deliver the solution to the skin, wipes of 80% polyester and 20% viscose rayon were cut into squares (7×8 cm, 0.45 g each), and an accurate amount (2.5 mL) of the test solution was added to the wipes using a dropper bottle. Delivery and scoring of the effects. An average volume of 74 ± 2 μL containing the test component was rubbed onto the receptive field of the nerve of the zygomatic prominence (zygomatic bone). As before, the sensory effects of coldness / chill were recorded at 5-minute intervals and 10-minute intervals. Quarter-point and half-point scores were allowed. When two zeros were observed at 10-minute intervals, the scoring was stopped. At least 4 trials were conducted for each concentration for 2 - 3 volunteer subjects for each compound. The results of testing DIPA-1-8 at three concentrations are shown in Figure 3.

[0155] Figure 3 shows the cooling sensations caused by topically applying various concentrations of DIPA-1-8 to the skin on the zygomatic process. The cooling effect can be measured as the area under the intensity / time curve (AUC) or the time to half-maximum effect (T-1 / 2) using the software of the GraphPad Prism package. The graph shows the AUC dose-response curves when the compound DIPA-1-8 was applied at 0.5, 1, and 2% (5, 10, and 20 mg / mL dissolved in distilled water).

[0156] A comparison of the DIPA diisopropyl analog (3,3-X) and the mixed propyl-sec-butyl analog (3,4-X) is shown in Figure 4. A statistically significant difference (P < 0.01) was seen between the 3,3-X and the asymmetric chiral 3,4-X analogs. 3,4-8 and 3,4-9 formed a milky / small oil droplet emulsion at 20 mg / mL.

[0157] In particular, DIPA-1-7 selectively produced an extraordinary sensation of "dynamic coldness" and also had an anti-fatigue effect. From the above data, it can be seen that among these compounds, DIPA-1-7 induced "dynamic coldness" on both the periorbital area and the surface of the zygomatic bone / forehead. Another compound with similar properties was DIPA-1-8, which was a further coldness / frostbite cold, but had the desirable property of a long duration of action on the surface of the zygomatic bone / forehead. The long duration of action of DIPA-1-7 and DIPA-1-8 on the skin increases their value as an antipruritic. As shown in the following case study, a single application of DIPA-1-7 was sufficient to relieve itching.

[0158] The special value of DIPA-1-9 is the pleasant cooling it provides, the long duration of action after periorbital application, and the absence of any stinging. Therefore, it has a special therapeutic niche for reducing sensory abnormalities of the transitional epithelium, particularly of the eyelids and conjunctiva. The selective attributes of DIPA-1-7 and DIPA-1-8 are unexpected and surprising and have practical uses for sensory abnormalities.

[0159] Study 4 The agonist activity of compounds against TRPM8. Using a Fluo-8 calcium kit and a fluorescence imaging plate reader (FLIPR TETRA (trademark)) instrument, the in vitro effects of the first set of test compound sets (Table 8) against the cloned hTRPM8 channel (encoded by the human TRPM8 gene and expressed in CHO cells) were evaluated. The assay was performed by ChanTest Corp. (14656 Neo Parkway, Cleveland, OH 44128, USA).

[0160] Test compound and positive control solutions were prepared by diluting the stock solutions with HEPES-buffered physiological saline (HBPS) solution. The test compounds and control formulations were loaded into polypropylene or glass-lined 384-well plates and placed inside the FLIPR device (Molecular Devices Corporation, Union City, California, USA). The test compounds were evaluated at 4 or 8 concentrations with n = 4 replicates per measurement. The positive control reference compound was L-menthol, a known TRPM8 agonist. The test cells were Chinese hamster ovary (CHO) cells stably transfected with human TRPM8 cDNA.

[0161] In the FLIPR TETRA (trademark) assay, cells were seeded at approximately 30,000 cells per well in a 384-well black wall flat bottom clear microtiter plate (type: BD Biocoat poly-D-lysine multiwell cell culture plate). The cells were cultured overnight at 37 °C to reach a nearly confluent monolayer suitable for the fluorescence assay. The test procedure was to remove the growth medium and add HBPS (40 μL) containing Fluo-8 at 37 °C for 30 minutes. 10 μL of the test compound, solvent, or control solution in HBPS was added to each well and read for 4 minutes. Concentration-response data were analyzed via the FLIPR control software attached to the FLIPR system (MDS-AT) and fitted to a Hill equation of the following form.

Equation

Table 8

[0162] Of the 12 compounds tested, all showed full efficacy against the TRPM8 receptor. That is, at the high concentrations tested, calcium influx was stimulated by approximately 100%, and the data was fitted to a sigmoid dose-response curve. The results of the "diisopropyl" compounds of the present invention are shown in Figure 4. The EC50s of the more potent compounds (DIPA-1-7, DIPA-1-8, DIPA-1-9, 2-5, 2-6, 2-7, 2-8) fell within a narrow range where the 95% confidence intervals overlapped. The potencies of DIPA-1-7, DIPA-1-8, and DIPA-1-9 were equivalent to and significantly greater than those of DIPA-1-5 and DIPA-1-6. In contrast, the structural modifications of comparative compounds 3-1 and 3-2 resulted in a significant loss of biological activity.

[0163] To investigate the specificity of the test compounds, further studies were conducted on the TRPV1 channel (human TRPV1 gene expressed in HEK293 cells) and the TRPA1 channel (human TRPA1 gene expressed in CHO cells). The test cells were Chinese hamster ovary (CHO) cells or human embryonic kidney (HEK) 293 cells transfected with human TRPV1 or TRPA1 cDNA. The positive control reference compounds were capsaicin (a known TRPV1 agonist) or mustard oil (a known TRPA1 agonist). DIPA-1-7 and DIPA-1-8 showed no agonist or antagonist activity against the TRPA1 channel at the maximum test concentration of 100 μM. For DIPA-1-7, weak TRPV1 agonist activity was found, but this was not dose-dependent.

[0164] In the bioactivity studies, the potency was not correlated with the TRPM8 EC50. For example, DIPA-1-5 and DIPA-1-6 were more potent in inducing shivering behavior than DIPA-1-7 and DIPA-1-8 [see Study 5]. There were no prominent features in the TRPM8 EC50 data that enabled prediction of which compounds had potent "dynamic cold" properties in vivo.

[0165] Additional tests were carried out with the "mixed" isopropyl - sec - butyl phosphoryl hexane and heptane analogs. The data were collected by Andersson et al. of King's College (London, UK) using the method described below: "Modulation of the cold - activated channel TRPM8 by lysophospholipids and polyunsaturated fatty acids. Journal Neuroscience 27(12):3347 - 3355, 2007". In this specification, the effect of test compounds on TRPM8 expressed in Chinese hamster ovary cells was studied using the intracellular penetration of the calcium - sensitive dye Fura - 2. Cells grown in culture were seeded overnight at a density of approximately 30,000 cells / well, loaded with 2 μM Fura - 2 (Molecular Probes, Leiden, Netherlands) for approximately 1 hour, and then placed on a glass coverslip. The test solution was added with a micropipette placed near the cell. Using excitation wavelengths of 340 and 380 nm and an emission wavelength of 520 nm, the luminescence intensity from the cell was measured every 4 or 5 seconds for 90 seconds. The fluorescence emission intensity ratio (R, within individual cells) at 340 nm / 380 nm excitation was recorded using the FlexStation and ImageMaster suite of software (PTI, South Brunswick, NJ). Samples were tested 3 times at each concentration, and the mean values were analyzed by non - linear regression using a point sigmoid function approximation to obtain the estimated EC50 (median effective concentration) (GraphPad Prism software, La Jolla, CA).

[0166] The potencies of three analogs on the activation of TRPM8 (cold receptor) in transfected cells are shown in Figure 5. The unit on the vertical axis (Δ ratio) calculates the influx of the fluorescent calcium probe into the transfected cells. 3,3 - 7 (DIPA - 1 - 7) is significantly more potent than 3,4 - 6 and 3,4 - 7 (by approximately 10 - fold and approximately 5 - fold). It should be noted that 3,4 - 6 and 3,4 - 7 do not reach the same maximum efficacy for receptor activation even beyond the maximum concentration.

[0167] Figure 5 is a graph of the fluorescence response (Δ ratio 340 / 380) in cells transfected with TRPM8 as a function of the logarithm of the concentration (expressed in μM) of the test compound against DIPA-1-7 (black circles), 3,4-7 (white squares), or 3,4-6 (white triangles). The assay was performed by Andersson et al. of King's College (London, UK) using the method described below: "Modulation of the cold-activated channel TRPM8 by lysophospholipids and polyunsaturated fatty acids. Journal Neuroscience 27(12):3347-3355, 2007."

[0168] From these results, it is clear that the EC50 value does not provide information regarding the quality of the thermal extraction sensation, the duration of action, or the accessibility of the molecule to tissue targets. Identification of the selection factor requires a biological assay that directly addresses these questions.

[0169] Study 5 Activity in experimental rats: Animals covered with perioral and locally delivered fur and those with feathers shiver like wet dogs when wet and cold (see, e.g., Dickerson et al., 2012; Ortega-Jimenez et al., 2012; Wei, 1981). These shivers are rapid alternating contractions of the extensor and flexor muscles around the spinal axis and can be easily observed and counted. "Wet dog shivers" have been studied in detail in animals and this behavior is interpreted as having survival value. The reason is that shivering reduces the need to consume evaporative energy to remove moisture by removing water from the skin. Thus, the sensation that triggers shivering is water being trapped between hair follicles or feathers. Humans have little hair on their skin and usually do not shiver, but a few individuals emerging from a cold pool can mimic this wet shiver. In humans, a behavior equivalent to possible shivering is shuddering (a state caused by a systemic sensation of coldness / cold and wetness).

[0170] Drug-induced shivering in animals has been reviewed (see, e.g., Wei, 1981). Under suitable conditions, drug-induced shivering can be observed in pentobarbital-anesthetized rats, which is enhanced by hypothermia and cold and suppressed by an increase in body temperature. Here, "wet dog shivers" were evaluated as a model of dynamic cooling for test compounds. Using a standardized procedure, test compounds were compared for their ability to stimulate a shivering response by oral administration and local delivery to the abdominal skin.

[0171] Perioral. Test compounds were dissolved in saline and orally gavaged at 20 mg / kg (a volume of 0.1 mL / 100 g body weight) to male albino rats anesthetized with pentobarbital [N = 3 - 4 rats per compound]. Shivering was counted over a 40-minute period and recorded at 10-minute intervals.

[0172] Three of the four “diisopropyl” compounds caused violent shaking. The “di-sec-butyl” compound was relatively inert, except for causing an average of four tremors during the 40-minute observation period. In contrast, the average tremor frequencies of DIPA-1-5, DIPA-1-6, and DIPA-1-7 were 86, 56, and 36 tremors, respectively. The strong activity of DIPA-1-5 was exceptional. When applied to the skin, DIPA-1-5 had a refreshing “dynamic coldness,” but its duration of action of about 30 minutes was significantly shorter compared to DIPA-1-6 and DIPA-1-7. Due to the short duration of action of DIPA-1-5, its practicality is limited. The small molecular size promotes absorption and allows access to systemic receptors, which may result in further tremors. The relationship between the tremor response and the temperature sensation was further studied [in rats under pentobarbital anesthesia]. After injection of the anesthetic, the rectal temperature drops and reaches about 35 °C in about 10 minutes. This hypothermia can be overridden by placing the animal on a heated surface and maintaining the body temperature at 38 °C. When DIPA-1-7 (20 mg / kg) was administered around the mouth, 36 ± 5 tremors (N = 6) were induced in anesthetized rats, but the frequency of tremors was significantly reduced to 5 ± 2 (N = 6) in warmed animals [P < 0.001]. The two-thirds reduction in the frequency of tremors in the heat indicated that the tremor response was associated with the sensation of cold and shivering.

[0173] Local. Tremors are an excellent indicator of in vivo effects. A method was developed to determine whether tremors are seen after topical application of DIPA compounds. As shown in Figure 6, the skin of the abdomen of pentobarbital-anesthetized rats was shaved, and 20 μL of pure DIPA was applied with a micropipette onto a circle with a diameter of about 1 cm surrounded by a ring of skin cream [Baby cream “Nevskaya kosmetika Detskyi” Nevskaya Kosmetika Inc., Saint-Petrsburg 192029]. One hour after application, the number of tremors was counted.

[0174] Figure 6 shows a method for measuring the transdermal activity of the DIPA compound applied with 20 μL by micropipette to the center of a circle surrounded by cream on the abdominal skin of an anesthetized rat. The frequency of tremors was counted 1 hour after topical application. Data and results regarding the local response around the mouth are summarized in Table 9. The data are further plotted in a graph in Figure 6, indicating no correlation between the potency of TRPM8 and the in vivo biological activity.

[0175] The data in Table 9 and Figure 6 strongly demonstrate the novelty and excellent properties of the compounds of this discovery. It is clear that these compounds permeate biological membranes and cause rapid responses (an event not seen with the comparative di-sec-butyl analog). Furthermore, the biological activity does not correlate with the potency measurement value [EC50] for the TRPM8 receptor. Such a large tremor response was seen for the first time after topical (skin) application of a chemical substance.

Table 9

[0176] Surprisingly, when using DIPA-1-5, DIPA-1-6, and DIPA-1-7 of the embodiments of the present invention, intense tremors were induced. In DIPA-1-8, only a weak response was observed, and the comparative di-sec-butyl analogs 2-5, 2-6, and 2-7 were inactive. The tremors induced by DIPA-1-7 were dose-dependent. When 5 μl, 10 μl, 20 μl, or 50 μl of DIPA-1-7 was topically applied, an average of 25 ± 3, 53 ± 6, 79 ± 8, and 118 ± 12 tremors per hour were caused, respectively. When DIPA-1-7 was diluted 50-50 with either water or saline (at a 10 μl dose), tremors were observed, but when 50% (R)-1,2-propanediol (at a 10 μl dose) was added to DIPA-1-7 as a diluent, the tremors were completely suppressed. This surprising result indicates that DIPA-1-7 penetrates the skin as an aqueous solution and is retarded by an alcohol solvent. This easy permeability of DIPA-1-7 is reminiscent of menthol and suggests that DIPA-1-7 can be easily delivered to the dermis by topical application. Furthermore, DIPA-1-7 can be used to penetrate thick keratinized skin lesions (such as those in psoriasis or hand contact dermatitis) in order to relieve itching and pain. Adjustment of the concentration of DIPA-1-7 in a polyhydric solvent (such as 1,2-propanediol) can be used to control the absorbance of DIPA-1-7, which is a technique well-known to formulation experts.

[0177] The surprising efficacy of DIPA-1-5 and DIPA-1-6 was unexpected. These molecules act on skin cooling in a shorter time than DIPA1-7. These small molecules can penetrate the skin barrier more quickly and enter the systemic circulation. However, the value of this rapid action is uncertain. In the most likely local applications of this discovery, it is desired that the action of the drug remains local rather than systemic. When comparing the relative activity of the analogs that cause tremors with the EC50 of TRPM8 activation, it can be seen that the two variables are not correlated. The limitations of TRPM8 EC50 for predicting biological activity have been previously examined.

[0178] The results in this specification provide the most powerful objective laboratory evidence that the DIPA compounds of Formula 1 selectively produce a strong "dynamic coldness". The total number of carbon atoms, or the number of carbon atoms in the largest alkyl group, was not correlated with the magnitude of biological activity. The key element for permeation was to avoid masking the phosphine oxide group.

[0179] Study 6 Water solubility and permeation to the target: The receptor targets of nerve endings are embedded in the epithelial cell layer. The thickness of the epidermis is only about 1 mm, but the stratum corneum containing a layer of dead cells and denatured proteins hinders the access of agonist molecules to the nerve endings. The heel of the foot is the thickest barrier (86 cell layers), followed by the palm of the hand, and then the back of the hand. When applying ice to the heel, it feels slightly cold, but when applying it to the sole of the foot with fewer layers, one will jump. As long as the skin of these surfaces is not structurally damaged (e.g., by inflammation), molecules cannot access the nerve endings, so applying a coolant will have no effect. On other surfaces, the skin of the genitals (the glans penis and vulva) and the eyelids are the thinnest, with 4 - 8 cell layers. The surfaces of the limbs, arms, and legs, and the trunk (torso) are thick. The scalp is intermediate. The face is diverse. The cheeks are relatively insensitive, but the areas around the cheekbones and nasolabial folds are thin and sensitive. These differences are important for the action of drugs. In the case of itching in the flexure of the limbs (e.g., elbows and knees), good drug permeation is required. In the case of the skin of the eyelids and genitals, molecules must be carefully selected to obtain the desired effect with gentle cooling and avoid excessive irritation.

[0180] In contrast to the compounds tested in ’496, Applicants' preferred embodiments of DIPA-1-7, DIPA-1-8, and DIPA-1-9, in which two of the alkyl groups (e.g., R2 and R3) are both isopropyl, have high water solubility and skin permeability. Increasing water solubility to enhance bioactivity runs counter to intuition in standard drug design. Typically, formulation experts attempt to break down the stratum corneum using penetration enhancers, and chemists attempt to increase the lipophilicity of the molecule (e.g., M. Prausnitz et al. Skin barrier and transdermal drug delivery. Chpt. 124, Medical Therapy, 2012). Nevertheless, the approach used herein has been met with clinical success.

[0181] Applicants have found that when the total number of carbons is equivalent and thus the molecular weight is equal, the water solubility of DIPA is at least two to three times that of DAPA. In the DIPA series, the polar phosphine oxide is not masked by extra branched-chain carbons. DIPA is more hydrophilic than DAPA. In vitro skin permeation studies in hairless mouse skin confirmed the extraordinary permeation power of the DIPA structure. In in vivo experimental animals, the pharmacological differences between DIPA and DAPA homologs were significantly different. Both DIPA and DAPA were active by intravenous injection, but only DIPA was active by topical or oral administration routes. This indicates that DIPA permeated the skin and gastrointestinal membrane, but the DAPA structure did not.

[0182] To further study the skin penetration of DIPA compounds, tests were conducted on the fluxes of DIPA-1-7 and DIPA-1-9 through the skin of hairless mice excised in vitro (Figure 7). Standard promoters with polyhydric alcohols (e.g., propylene glycol-oleyl alcohol mixture (50:50) or lauroglycol 90) designed to enhance permeability added to the 1-7 gel showed a ~50% decrease in the penetration rate, indicating that water solubility is important for penetration. In a study of the abdominal skin of anesthetized rats, when tested on the animal's skin with tremor as the endpoint, the 50:50 propylene glycol-DIPA-1-7 mixture was found to be inert, while pure DIPA-1-7 was very active. Thus, normal solvents or promoters of dermatological molecules do not promote but prevent DIPA from passing through the skin barrier.

[0183] Figure 7 shows the fluxes of DIPA-1-7 and DIPA-1-9 through the skin of hairless mice excised in vitro. The test chemicals dissolved in the gel were placed in an incubator for 8 hours, and the amount of chemical penetration was measured by high-performance liquid chromatography equipped with a refractive detector. These tests were conducted by Professor Choi at Korea University (South Korea). The flux of DIPA-1-7 was approximately 5 times that of DIPA-1-9. Standard promoters with polyhydric alcohols (e.g., propylene glycol-oleyl alcohol mixture (50:50) or lauroglycol 90) designed to enhance permeability added to the DIPA-1-7 gel showed a ~50% decrease in the penetration rate, indicating that water solubility is important for penetration.

[0184] The motility of DIPA molecules in an aqueous environment that has passed through the skin barrier is extraordinary and surprising. Apparently, when one or more carbon (e.g., methyl) groups mask the polar "head", water solubility and permeability decrease. Alternatively, until reaching the TRPM8 receptors in the basal layer, DIPA may be able to efficiently pass through the pores of the stratum corneum into the extracellular fluid due to the symmetric (achiral) arms (isopropyl groups). The DIPA structure can be regarded as a "sperm"-like head (oxygen cloud around the phosphorus atom) that enables polar interactions with water. When the branched arms are asymmetric (chiral), the "swimming" movement can be impaired.

[0185] Study 7 Effects on local sites of the skull. DIPA-1-7, the most potent compound for dynamic cooling, was tested at local sites of the skull. Using a cotton wipe, a 20 mg / mL solution was applied to the skin of the upper cheek, the buccal masseter parotid region of the earlobe, the temple, and the upper skin around the auricle, as well as to the posterior mandible using appropriate skull measurement points as landmarks (pterion, colonion, codilion, and gonion, respectively). Cooling was hardly observed at these sites other than the cheek. Mild cooling was observed in the cheek for about 30 minutes, and this effect may be due to the solution spreading into the receptive field of the infraorbital nerve. However, it should be noted that the sensory effect of local application of DIPA-1-7 can be affected by inflammatory lesions (e.g., seborrheic dermatitis or psoriasis) that can change permeability. In such cases, DIPA-1-7 is very effective against itching.

[0186] The head is known to be a site where cooling helps reduce the discomfort of heat. In the study described by Nakamura et al.

[2012] , 11 male subjects were exposed to mild heat. Subjects wearing only shorts entered a climatic chamber maintained at 32.5 ± 0.5 °C and 50% relative humidity. Approximately 1.5 hours after entering the chamber, a water perfusion stimulation device was installed on the head, chest, abdomen, or thigh to initiate a local cooling protocol. The subjects felt that cooling of the face and thigh was more effective than cooling of the chest and abdomen in reducing the discomfort due to heat.

[0187] In the study described by Essick et al. [Site-dependent and subject-related variations in perioral thermal sensitivity. Somatosensory & motor research 21, 159-75, 2004], thresholds for the detection of cooling and cold were determined for 34 young adults at various sites on the face, ventral forearm, and scalp. The most sensitive sites were the lips, which could detect a temperature change of about 0.5°C, followed by the areas around the mouth (hairs on the upper and lower lips, commissures) and the sides of the jaw. The skin in the center of the cheek and around the auricle was less sensitive (able to detect a temperature change of about 2°C), and the forearm and scalp were the least sensitive (able to detect a temperature change of about 3°C). The sensitivity of the skin of the orbit, zygoma, and forehead was not tested.

[0188] Case studies demonstrating the use of DIPA in skin diseases are described below: (a) Contact dermatitis and atopic dermatitis: to relieve the itching and pain of the skin of subjects experiencing these skin symptoms, (b) Dry skin in the elderly: to break the vicious cycle of "itching and scratching", (c) Urticaria: to reduce symptoms, (d) Pruritus due to cholestasis in patients with liver disease: to reduce symptoms, (e) Itching of the scalp, (f) Pruritus due to cholestasis, (g) Itching of the eyes: to reduce the discomfort of blepharitis, and (h) Lichen sclerosus: to treat the discomfort of genital inflammation. A comparison of the effectiveness between DIPA analogs was also conducted. In some of these symptoms (e.g., urticaria and pruritus due to cholestasis), it was surprising that the DIPA compound was effective even when the keratinized skin was "intact" (i.e., the stratum corneum was normal), and it was not possible to expect that topical therapeutic agents would penetrate and be effective.

[0189] In these studies, the subjects were administered DIPA-1-7, a 1.5% wt. / vol commercial gel (Intrinsic B, Dong Wha Pharmaceuticals, Seoul, Korea), or individual dosage units containing 1.5 - 1.75 mL of DIPA-1-7 stored in 2.0 mL microcentrifuge tubes (Nova Biostorage Plus, Canonsburg, Pennsylvania), and cotton gauze (0.4 g, rectangular, 50 mm × 60 mm, CS-being, Daisan Cotton, Japan). In the case of wipes, DIPA-1-7 was provided as a solution in distilled water (concentration of DIPA-1-7 being 5 mg / mL - 20 mg / mL). The subjects were instructed on how to place and rub the wet gauze on the skin. By these application methods, approximately 0.15 mL - 0.35 mL per unit wipe was delivered. The subjects were instructed to rinse with water if any surface became hypersensitive, but no irritation or discomfort was seen at the test concentrations of DIPA-1-7, DIPA-1-8, or DIPA-1-9.

[0190] Case Study 1 Contact dermatitis. Two scientists working in a laboratory suffered allergic dermatitis of the hands in response to detergents and soaps. The hands were inflamed and severely itchy. When DIPA-1-7 (20 mg / mL) was applied with an applicator or gauze with cotton tips, the itching stopped immediately, and this effect lasted for at least 2 hours, and by repeated application, the suppression could be restored. A scientist, a world-renowned dermatologist with numerous publications on itching, noted that DIPA-1-7 produced a "freezing cold" sensation on the inflamed skin and that he had never encountered a compound so effective in stopping itching so quickly.

[0191] A pharmacologist liked to work in the garden, but the stems of bougainvillea and the thorns of rose thickets, and the hairs on the leaves of azaleas irritated his skin, causing intense itching. He pointed out that by applying DIPA-1-6 or DIPA-1-7 as a 20 mg / mL aqueous solution or as a cream (mixed with Eucerin moisturizing cream), the sensory discomfort of the skin could be immediately stopped. He also obtained these effects using DIPA-1-8. He also pointed out that the irritation and itching caused by insect stings could be immediately stopped by these agents.

[0192] Case Study 2 Atopic dermatitis. An 8-year-old boy had suffered from atopic dermatitis since childhood and showed standard scars on the flexures of his elbows and knees. He had been treated with topical steroids, but his skin had become thin and easily broken. He opposed topical ointments because he felt they were ineffective in stopping itching as they were overly "oily" and sticky. He also used a moisturizer. Itching, especially during periods when allergic rhinitis worsened, disturbed his sleep. His parents were worried about nocturnal scratching and about his poor academic performance and lack of concentration. The subject was given an 8×8 cm wipe saturated with 2 mL of 10 mg / mL DIPA-1-7 in water and given instructions to use the wipe after washing as part of his bedtime routine and apply it over itchy skin areas at night. The wipe was directly effective in reducing itching and scratching and promoted sleep. With two weeks of use, the redness of the skin lesions faded, crusts formed, and healing progressed. It was clear that the vicious cycle of itching and scratching had diminished. The boy became brighter and paid more attention to his schoolwork. His parents were very happy.

[0193] Case Study 3 The pruritus and xerosis of an elderly person (an 86-year-old retired widower) who decided to move from California to a suite in a hotel in Hong Kong for permanent residence. He had been an enthusiastic and skilled golfer for many years and suffered from actinic keratosis and dry skin. Over time, especially the skin on the back of his forearms and torso became itchy. Scratching his back with a wooden stick initially helped, but the skin became damaged, infected, and inflamed. He applied "Atopy Control" made by Eucerin, which was found to reduce dryness but was expensive, heavy, and "oily", yet it did provide some degree of protection and relief. During the hot summer in Hong Kong when the air conditioner was on full blast, and during the dry autumn season, the itchy and inflamed skin became intolerable. The dermatologist prescribed a strong topical steroid, but his skin became vulnerable in some areas, infected, and ulcers formed. Due to the skin discomfort, his life became miserable. He agreed to try the 10 mg / mL DIPA-1-8 solution in isotonic saline. He applied approximately 20 drops of DIPA-1-8 to an 8×8 cm wipe made of 100% viscose (50 grams per square meter). After application, the amount adhering to the skin was approximately 0.2 - 0.25 mL, so the total dose per application was 2 - 2.5 mg. When DIPA-1-8 was applied topically, his itching was relieved within 3 - 5 minutes after wiping, and he no longer complained of skin discomfort. His live-in nurses noticed that he no longer scratched as much as before. He found that the wipe gave a wet feeling when applied to the face and could thus be useful for cosmetic purposes. He continued to use the wipe as needed, and crusts formed on the skin, healed, and returned to a normal appearance. His only negative comment was that he felt too cold with this solution when the air conditioner was set stronger. He continued to use this wipe until he died of bulbar palsy three years later.

[0194] Case Study 4 Urticaria. Urticaria (urticarial papules) is a human allergic symptom that appears as a skin rash (wheals). The symptoms of skin redness, swelling, and itching are mainly caused by the release of histamine from mast cells into the dermis. A common trigger for urticarial papules is the ingestion of seafood. This document describes a case of urticaria treated with DIPA-1-7 formulated at 1.5% wt. / vol in a gel manufactured by Dong Wha Pharmaceuticals (Seoul, Korea). A female subject with a history of urticarial papules went to a seaside resort in the south of France and consumed seafood pasta, crab mince, and seafood mixed soup over a two-day period. She developed extensive hives on her buttocks accompanied by the typical signs of inflammation: "heat sensation" (feeling hot when touching the inflamed tissue), "erythema" (redness caused by vasodilation), "swelling" (edema), and "pain" (pain and itching). Hives also appeared on the skin above the collarbone and on the neck. It was miserable. When the gel was applied to the skin, all four signs of inflammation that began approximately 5 - 10 minutes after application decreased. The subject described the effect as a "tingling coldness" and then a strong coldness, but also described it as excellent in reducing the itching and the "heat" sensation from the red hives. Swelling, redness, and "erythema" were visibly reduced 30 minutes after application. The gel was applied again 3.5 hours later, and then the subject was administered 3 tablets (120 mg) of fexofenadine tablets and 1 tablet (4 mg) of chlorpheniramine tablets. All signs and symptoms of urticarial papules were seen as at least 50% reduced and "under control" by the subject within 12 hours, and the skin rash disappeared after 3 days and did not recur.

[0195] This is the first report that cutaneous paresthesias (itching and heat sensations) caused by urticaria and other signs of inflammation rapidly decreased after topical treatment with a topical therapeutic agent (1.5% DIPA-1-7 in gel). The effect of applying DIPA-1-7 to relatively thick buttock skin (15 - 18 cell layers in the stratum corneum) appeared immediately, indicating that it penetrated into nerve endings and enabled the alleviation of inflammatory symptoms and signs. With its therapeutic effect and rapid onset, it is potent enough to provide benefits to patients. Renowned dermatologists at a top hospital in Seoul, South Korea, conducted additional case studies using DIPA-1-7 gel in 8 cases of urticarial skin diseases. Satisfactory itch suppression was obtained in 75% of the patients. In this study, there were 5 cases of atopic dermatitis, 6 cases of seborrheic dermatitis, 3 cases of prurigo nodularis, and 3 cases of herpes zoster. In the cases tested, after using DIPA-1-7 for 1 week, the intensity of cutaneous paresthesia was evaluated using a visual analog scale. It was clear that DIPA-1-7 gel was effective against various skin diseases. These results are currently published as: Jung MJ, Kim JC, Wei ET, Selescu T, Chung BY, Park CW, et al. A randomized, vehicle-controlled clinical trial of a synthetic TRPM8 agonist (Cryosim-1) gel for itch. J Am Acad Dermatol 84(3):869 - 71.

[0196] Case Study 5 Scalp itching. The scalp is a site where itching often occurs. Local treatment is practical, but the target and lesion are often difficult to visualize. Factors (such as hair, sebum, and scalp thickness) also affect the penetration of drugs to the target. Therefore, effective treatment of scalp itching is an unmet medical need. A common trigger for scalp itching is the use of hair color. Scratching the scalp can also increase under psychogenic stress, but scratching is considered unhygienic and encounters social prejudice. The inventors conducted research on human subjects with scalp itching and published the results [Kang SY, Choi MG, Wei ET, Selescu T, Lee SY, Kim JC, et al. TRPM8 agonist (cryosim-1) gel for scalp itch: A randomized, vehicle-controlled clinical trial. J Eur Acad Dermatology Venereol. 2022;1-2]. Subjects with scalp itching were treated with DIPA-1-7 formulated at 1.5% wt. / vol in a gel manufactured by Dong Wha Pharmaceuticals (Seoul, Korea). Subjects with scalp itching (a total of 25 - 31) participated. There was a clear and significant reduction in the scalp itching of the test subjects. This is the first double-blind report in which a topical coolant was used for the treatment of scalp itching. With its therapeutic effect and rapid onset, it is potent enough to benefit patients. These patients had severe itching but no visible lesions on the scalp.

[0197] Case Study 6 Biliary stasis pruritus. An 80-year-old famous history professor was diagnosed with end-stage cirrhosis and had developed severe disseminated scabies. Due to the subject's incessant itching and scratching, his children heard about the DIPA anti-itching treatment and requested a sample. The subject's skin was intact and there were no rashes. The condition was diagnosed as biliary stasis itching. The subject was given a square cotton gauze and a 30 mL plastic dropper bottle containing a 2% DIPA-1-7 aqueous solution. He was instructed to moisten the square and apply the solution to the itchy areas as needed. The subject asserted that this was the best treatment he had ever tried for itching and it was effective after the first trial. He used about one 30 mL bottle every three days and requested more. This regimen was continued until the subject died three months later.

[0198] Case Study 7 Eye itching due to various etiologies. A 28-year-old female subject visited an ophthalmologist complaining of dry eye disease, namely discomfort on the eye surface, blurred vision, a burning sensation, hypersensitivity to light, and problems related to reading, driving, and using a smartphone screen. Upon examination, her findings included congestion at the edge of the eyelid, obstruction of the meibomian gland ducts, some thickening at the edge of the eyelid suggesting epithelial keratinization, and makeup flakes in the eyes. Further questioning revealed that she had been using bimatoprost solution to induce hirsutism as she was dissatisfied with the slow growth rate of her eyelashes, but she had been applying the solution twice or three times a day (instead of the recommended once a day application).

[0199] She was diagnosed with blepharitis and conjunctivitis and was instructed not to wear eye makeup. She was given Blephaclean (trademark) eye wipes (single-unit wipes containing a cleansing solution) to clean the meibomian ducts and maintain eye hygiene. However, the subject strongly objected to the irritation caused by the cleansing wipes and the continued use of the very expensive bimatoprost solution. The subject was enrolled in a clinical trial of DIPA-1-9 wipes (dissolved at 2 mg / mL in water) and was instructed to use one wipe in the morning and one in the evening, and up to two additional wipes during the day as needed. She reported an immediate improvement in her mood when using the DIPA-1-9 wipes and commented on the cooling and refreshing sensations now present on the ocular surface and eyelid margin. She stated that the irritation from the bimatoprost solution immediately disappeared and her eyelashes immediately became thick and lush. The blepharitis and conjunctivitis resolved. She recommended adding DIPA-1-9 as an adjunct to the bimatoprost solution. She offered to pay for a continued supply of the DIPA-1-9 wipes.

[0200] Recent research on the treatment of eye disorders in human subjects has been published (Yoon HJ, Kim J, Yang JM, Wei ET, Kim SJ, Yoon KC. Topical TRPM8 Agonist for Relieving Neuropathic Ocular Pain in Patients with Dry Eye: A Pilot Study. J Clin Med. 2021;10(2):250).

[0201] Case Study 8 Lichen sclerosus. A 40-year-old man suffering from penile lichen sclerosus. This is an inflammatory skin disease of the glans penis and prepuce, and in this particular case, it was accompanied by severe itching and paresthesia (a burning sensation). The patient volunteered to try DIPA-1-8 on the affected area under the supervision and care of a dermatologist and was given various concentrations of DIPA-1-8 dissolved in distilled water. After self-experimentation, he concluded that significant relief occurred when the concentration of DIPA-1-8 was 1 - 1.5 mg / mL, and it was too cold and uncomfortable when the concentration of DIPA-1-8 was 2 mg / mL. The solution was applied using an applicator with a cotton tip or a gauze wipe. The advantage of using DIPA preparations on genital skin is that they are water-soluble. This minimizes the need for excipients and the potential for further irritation. The subjects suggested that aerosol sprays could also be a convenient method of drug delivery.

[0202] Commercially available samples of 1.5% DIPA-1-7 gel (known as Intrinsic B in Korea) became available, and further evaluation could be carried out in several female patients with lichen sclerosus. These patients stated that when applied to wounds with scabs caused by scratching, the gel initially caused a strong stinging sensation, but it helped to suppress scratching behavior caused by episodic itching in social situations. Another group that benefits from DIPA wipes are postmenopausal women with a history of breast cancer. Hormone replacement therapy (HRT) cannot be used in this group, and with aging, the vulvar epithelium atrophied along with a reduction in vaginal secretions. These symptoms cause itching, which is alleviated by using 1% DIPA-1-8 wipes.

[0203] These studies particularly demonstrate the anti-nociceptive properties of DIPA-1-7 and DIPA-1-8 against genital itching. DIPA-1-8 may be a more favorable drug for dermatological use as it has a longer duration of action than DIPA-1-7. Further studies have shown that when 2 mg / mL of DIPA-1-9 is applied using a wipe on the glans or vulva, a gentle cooling and refreshing sensation alleviated the discomfort due to inflammation.

[0204] Case Study 9 Three subjects decided to systematically compare DIPA-1-6, DIPA-1-7, DIPA-1-8, and DIPA-1-9 for their sensory effects on the ocular surface. Each compound was prepared at 1 mg / mL in distilled water. An applicator (Puritan 803-PCL) with a cotton tip of a specific size consisting of a cotton ball (55 - 75 mg) wrapped around the tip of a 3-inch polystyrene rod was dipped into the solution. Next, with the eyelids closed, the tip was applied under the upper eyelid, above the eyelashes, from the outer to the inner side, with two wiping motions. Thereafter, the subjects were instructed to blink. Next, blinking was used to evenly disperse the solution across the entire precorneal film. By this "swab" delivery method, a total of approximately 35 μL of liquid was pressed onto the surface of both eyes. DIPA-1-6 caused significant stinging and discomfort and, therefore, no further studies were conducted. DIPA-1-7 and DIPA-1-8 produced a strong and refreshing cooling, alleviated eye irritation, and enhanced cognitive function. For example, the subjects felt that they could focus on distant objects and enjoy the scenery. They felt mentally sharp and refreshed. However, with both DIPA-1-7 and DIPA-1-8, small residues remained on the eyelids, and subsequent washing of the face with a towel could cause eye irritation. Surprisingly, DIPA-1-9 did not irritate the eyes when applied to the eyelids and left no residues. A refreshing cooling was also obtained, but it was not as strong as that of DIPA-1-7 or DIPA-1-8. On the other hand, DIPA-1-9 has ideal properties for the treatment of eye discomfort (e.g., discomfort caused by the following): eye strain; visual fatigue; ophthalmic surgery; airborne irritants or contaminants interacting with the ocular surface; prolonged wear of contact lenses; excessive exposure to sunlight; conjunctivitis; conjunctivitis in atopic dermatitis patients treated with dupilumab; or dry eye syndrome. Some of these results have been published as follows: Yang JM, Li F, Liu Q, Ruedi M, Wei ET, Lentsman M, et al. A novel TRPM8 agonist relieves dry eye discomfort. BMC Ophthalmol. 2017;17(1).These towels for the treatment of eye discomfort and eye fatigue are available in Korea as a product called OcuCool. Of particular interest is the good efficacy of OcuCool when treating the itching of conjunctivitis in atopic dermatitis patients administered dupilumab.

[0205] Summary of observations The structures of Rowsell and Spring ’496 were described over 40 years ago but were not developed for use. The applicant found that the diisopropyl analogs are not described in ’496. These analogs were then synthesized and tested. The “head” of a typical DIPA molecule is polar (hydrophilic) and soluble in the polar environment of water. This increased water solubility of the analogs paradoxically promotes penetration through the dead cell layer of the stratum corneum to access the receptors of the nerve endings in the skin. Preferred embodiments 1-7 and 1-8 exhibit a strong cooling sensation that can modulate paresthesia caused by various dermatitides (e.g., atopic dermatitis or urticaria) and dryness (xerosis). This occurs in skin diseases where the skin is intact (e.g., urticaria, cholestatic pruritus). In the transitional epithelium of the eyelid and anogenital margins, DIPA-1-9 is surprisingly active, but there is no “freezing cold” effect like that of DIPA-1-7.

[0206] The applicant found that when the total number of carbons is equivalent and thus the molecular weights are equal, the water solubility of DIPA is approximately 10 times. The permeation power of DIPA was confirmed by in vitro skin permeation studies on the skin of hairless mice. In in vivo experimental animals, the pharmacological differences of DIPA from the mixed isopropyl / sec-butyl and di-sec-butyl homologs were significantly different. Both DIPA and di-sec-butyl were active by intravenous injection, but only DIPA was active by topical or oral administration. This indicates that DIPA penetrated the skin and gastrointestinal membrane, but the di-sec-butyl structure did not. The ability of the DIPA structure to reduce skin discomfort in patients with intact stratum corneum and skin diseases was rapid, dramatic, and unexpected.

[0207] The ’496 structure has its “head” more covered with lipophilic groups, is chiral, and has a lower ability to penetrate the target receptor in the basal layer of the skin and achieve the same therapeutic endpoints as the preferred embodiments. Increasing water solubility runs counter to intuition in standard drug design for enhancing transdermal drug penetration. Usually, formulation experts try to break down the stratum corneum using penetration enhancers, and chemists try to increase the lipophilicity of the molecule (e.g., M. Prausnitz et al. Skin barrier and transdermal drug delivery. Chpt. 124, Medical Therapy, 2012). Nevertheless, the approach used herein has been met with clinical success. These observations are now emphasized by the publication of appropriately designed clinical trials in reputable academic journals. Accordingly, the applicant states the view that the discovery of the DIPA embodiments for skin diseases is a leap forward in the discovery process.

[0208] References. A number of publications are cited herein in order to more fully describe and disclose the present discovery and the state of the art related to that discovery. Each of these publications is hereby incorporated by reference in its entirety.

Claims

1. A method for treating a target eye disease, wherein the target requires the treatment, and the method comprises topically administering a liquid or semi-liquid composition containing a therapeutically effective amount of a compound of formula 1 to the target: 【Chemistry 1】 (In the formula, R is n-heptyl, n-octyl, or n-nonyl).

2. The method according to claim 1, wherein the composition is administered to the surface of the eye, the skin around the eye, or the eyelid of the subject.

3. The method according to claim 1 or 2, wherein the composition is administered to the eyelid(s) of the target.

4. The method according to claim 1, wherein the eye disease is blepharitis or conjunctivitis.

5. The method according to claim 4, wherein the conjunctivitis is allergic conjunctivitis or non-infectious conjunctivitis.

6. The method according to claim 1, wherein the eye disease is itching or pain in the eye or the skin area surrounding the eye.

7. The method according to claim 1, wherein the composition is a liquid containing water or an isotonic saline solution as a solvent.

8. The method according to claim 1, wherein the compound of formula 1 is contained in the composition at a concentration of 0.5 to 20 mg / mL.

9. The method according to claim 8, wherein the compound of formula 1 is contained in the composition at a concentration of 0.5 to 5 mg / mL or 1 to 5 mg / mL.

10. The method according to claim 1, wherein the compound of formula 1 is 1-diisopropylphosphinoylheptane (DIPA-1-7), 1-diisopropylphosphinoyloctane (DIPA-1-8), or 1-diisopropylphosphinoylnonane (DIPA-1-9).

11. The method according to claim 1, wherein the administration is at least once a day.

12. The method according to claim 1, wherein the administration is at least twice a day.

13. The method according to claim 1, wherein the administration is for at least one week.

14. The method according to claim 1, wherein the administration is by a wipe or eye drop.

15. The method according to claim 1, wherein the compound of formula 1 is dissolved in the composition or exists as micelles.

16. The method according to claim 1, wherein the liquid or semi-liquid composition penetrates into the target skin after topical application, effectively reducing or eliminating inflammation or infection at or near the site where the composition is administered.

17. Use of the compound of Formula 1 for the manufacture of a drug for treating an eye disease by topical administration to the eyelid or another area of ​​skin around the eye of a subject requiring treatment. 【Chemistry 2】 (In the formula, R is n-heptyl, n-octyl, or n-nonyl).

18. The use according to claim 17, wherein the agent is a liquid or semi-liquid composition.

19. The use according to claim 17 or 18, wherein the drug is locally applied to another area of ​​the skin surrounding the eyelid(s) or eye(s) of the subject.

20. The use according to claim 17, wherein the compound of formula 1 is DIPA-1-7, DIPA-1-8, or DIPA-1-9.

21. The use according to claim 17, wherein the eye disease is dry eye symptoms, blepharitis, conjunctivitis, itching or pain in the eye(s) or the area of ​​skin surrounding the eye(s).

Images