Lipid-based formulation that increases penetration of the eyeball by anaesthetics for topical ophthalmic use

Abstract

The invention relates to a lipid-based formulation that increases the penetration of the eyeball by anaesthetics for topical ophthalmic use, wherein the formulation comprises: tetracaine (T), polyethylene glycol (PEG)-12 glyceryl dimyristate, ethyl alcohol, PEG(15)-hydroxystearate (Kolliphor® HS15), citric acid anhydride and sodium citrate dihydrate. The compound of the invention is characterised by low toxicity and in that it also acts as a permeability enhancer because it promotes molecule transport through the cell membranes, increasing the endocytosis rate and stimulating drug translocation via the paracellular route.

Description

[0001]LIPID-BASED FORMULATION THAT INCREASES PENETRATION OF TOPICAL OPHTHALMIC ANESTHETICS INTO THE EYEBALL. FIELD OF THE INVENTION The present invention generally falls within the field of tetracaine-based ophthalmic topical anesthetic formulations and methods of using the same. BACKGROUND OF THE INVENTION Proparacaine and tetracaine are two types of ocular anesthetic eye drops commonly used in ophthalmic surgeries and procedures to temporarily numb the surface of the eye and surrounding tissues. They belong to the class of medications known as topical ophthalmic anesthetics. These anesthetics are used to provide patient comfort during various ophthalmology office procedures and to provide anesthesia in eye surgeries and other procedures involving direct manipulation of or contact with the eye.Proparacaine and tetracaine act by blocking nerve signals at the site of application, inhibiting the transmission of pain signals from the nerves in the eye to the brain. Specifically, they reversibly block sodium channels in the membranes of sensory neurons, which are responsible for allowing the entry of sodium ions, which generate the action potential. By blocking these channels, proparacaine and tetracaine prevent the generation and propagation of the action potential. Therefore, pain signals on the surface of the eyeball (conjunctiva, sclera, and cornea) are interrupted. However, the internal tissues of the eyeball, such as the iris, ciliary body, and uvea, are not affected by it, since its penetration, like that of other topically administered drugs, is less than 3% due to the presence of ocular barriers.Likewise, the action of proparacaine and tetracaine is rapid and short-lived, so they must be instilled multiple times to achieve a sustained effect, since a single instillation usually lasts between 15 and 20 minutes. Considering that ophthalmic surgery is, by number, the most frequently performed surgery in the world, especially cataract surgery, it is imperative to have topical anesthetic alternatives with greater penetration and efficacy for these ophthalmic procedures. This would reduce potential complications from other administration routes such as peribulbar, retrobulbar, and general anesthesia. These complications include perforation of the eyeball, damage to ocular muscles, pain at the time of application, mechanical damage of the needle to the optic nerve in its intraorbital segment, and damage to the macular area.In order to generate greater penetration of topical ophthalmic anesthetics in an efficient and safe manner, and to avoid the risks associated with the administration of other anesthetic administration routes used in ophthalmological procedures, the presented invention is created, a lipid-based formulation containing anesthetic (tetracaine or proparacaine) for topical ophthalmic use, which increases the penetration of the active agents into the intraocular tissues of the eyeball. One justification for the present invention is the poor penetration of the eyeball of all topical ophthalmic drugs, which is less than 3%, including topical anesthetics such as tetracaine and proparacaine, severely limiting their action on intraocular tissues.The invention presented is a formulation to increase the penetration of the eyeball of topical ophthalmic anesthetics, and has the capacity to constitute a functional alternative for the prevention and / or treatment of potential complications associated with other forms of anesthesia administration, given that its lipid component ensures an increase in the penetration and bioavailability of anesthetics, in this case tetracaine or proparacaine, in the ocular white tissues. There are cases in which stabilizing molecules are administered within the state of the art, in those cases the subject will be administered a stabilizing composition according to a schedule that will be determined by the prescriber, which often ranges from once a week, once a month and once a year.In such cases, the stabilizing agent may be administered in the form of drops, following application of a topical ophthalmic anesthetic such as tetracaine hydrochloride, or following application of an acylating agent known to transiently open the corneal cell structure to permit penetration into the corneal stroma, or may be administered by direct injection into the corneal stroma, using a fine gauge needle, i.e., 30 or 32 gauge, or by controlled injection using a proprietary application device developed by Euclid Systems Corporation (patent pending).In the case where stabilizing eye drops are used, the drops can be administered after the application of a topical ophthalmic anesthetic, such as tetracaine hydrochloride, or after the application of an acylating agent known to transiently open the corneal cell structure to allow penetration into the corneal stroma. The drops can be administered directly to the cornea using an applicator designed to focus the delivery of liquids such as drops to the cornea, and to minimize exposure of the non-corneal surface to the drops. In cases where stabilizing molecules are used, drops of a standard topical anesthetic, such as tetracaine HCl, will generally be administered. Penetration of the stabilizer can also be used, for example, as described in PCT / US2009 / 037497.For example, drops of an acylating agent, such as glutaric anhydride, may be administered to facilitate penetration of the stabilizing molecules. Prior to administration of the acylating agent, drops of a slightly alkaline buffer will typically be applied. Generally, the eye will be thoroughly rinsed with physiological buffer, eye drops, or other physiological solution after administration of the stabilizing molecule solution drops. Natural stabilizing molecules have been described in U.S. Patents 6,946,440 (Euclid Systems Corp.), 7,402,562 (Euclid Systems Corp.), and Patent Application Publication 2009 / 0105127 (Euclid Systems Corp.). Stabilizing molecules have also been described in Chinese patents, for example: Invention CN104888286A relates to a tetracaine hydrochloride endoscope lubricant and a method of preparing the same.Tetracaine hydrochloride endoscope lubricant comprises one component with the following concentration, as shown in the specification. Tetracaine hydrochloride endoscope lubricant has the characteristics of simple and convenient intake and small application dosage, greatly simplifying the preoperative steps. Tetracaine hydrochloride endoscope lubricant is suitable for widespread use by medical personnel.While narcotizing a patient, the tetracaine hydrochloride endoscope lubricant is beneficial for the penetration and exit of the gastroscope, so that the patient's pain is greatly relieved; more importantly, the tetracaine hydrochloride endoscope lubricant has more excellent effects on foam removal and retention, and can effectively remove foam generated in the stomach, so that medical personnel can obtain a clearer observation view and the diagnostic accuracy of digestive tract diseases is substantially improved. The invention CN102579457B relates to a tetracaine-containing composition, as well as a method of preparing and applying the same. The composition comprises the following crude drugs: tetracaine, ephedrine, phenobarbital, diphenhydramine, hydrocortisone, and borneol.The tetracaine compound composition has the effects of removing necrotic tissue and promoting granulation, clearing heat and relieving pain, diminishing inflammation and resisting infection, and promoting wound healing. It has obvious curative effects in the treatment of acute anal fissures and acute attacks of chronic anal fissures. When the tetracaine compound composition is combined with an anal suppository to perform non-surgical treatment of hemorrhoids, the curative effects of the tetracaine compound composition in relieving bleeding, pain, and the abjective symptoms of hemorrhoids are obvious. Overall, the tetracaine compound composition has the advantages of an obvious curative effect, fast action, convenient use, and safety; and when the tetracaine compound composition is used, the patient feels no pain. Also American patents, such as U.S. Patent No. 1,889,645).There are many topical formulations on the market containing tetracaine hydrochloride, one of which is AME-30 TOP from TJ Smith & Nephew Limited, England (cf. GB 2,258,397-A) which contains 40 mg of active ingredient (4%, w / w), an aqueous gelling agent and a pharmaceutically acceptable salt. The invention US8609722B2 relates to compositions having a mixture of lidocaine, prilocaine and tetracaine, or their pharmaceutically acceptable salts. A preferred composition includes the following components in the approximate w / w percentages indicated: 1.5% lidocaine base; 1.5% prilocaine base; 4% tetracaine base and water. In some implementations, about 10% methylpyrrolidone; 2% dimethyl sulfoxide; 0.08% topical hyaluronidase; 1.5% guar gum; 1% polyoxyethylene sorbitan monolaurate; 0.5% polyoxyethylene sorbitan monooleate; and 100% water.Such compositions exhibit high skin concentration, deep anesthetic effect, and significantly faster onset of anesthetic effect than comparable transdermal anesthetics. A tetracaine / lidocaine eutectic mixture was discussed in U.S. Patent 4,529,601 issued July 16, 1985, but is not claimed. McCafferty et al. in their publications and patents [PCT / GB88 / 00416; GB2163956; Bro. J. Anaesth. 60:64 (1988); 61:589 (1988), 62:17(1989), 71:370 (1993)] reported various systems and formulations for noninvasive cutaneous anesthesia and discussed the advantages of a patch system over a more opaque cream system.They stated that an effective preparation must contain the minimum concentration of local anesthetic compatible with producing the desired clinical effect, and that onset times cannot be further reduced by increasing the concentration of local anesthetic in their formulations beyond a certain concentration. However, when we attempted to find prior art documents specifically directed to the composition of the present invention, none were found. The present invention seeks to promote the creation of functional therapeutic alternatives to significantly increase the percentage of penetration of the eyeball barriers to achieve therapeutic concentrations in target tissues (intraocular tissues) of topical ophthalmic anesthetics, in this case, tetracaine or proparacaine.Therefore, it impacts the pharmaceutical industry in ophthalmology, an active and highly productive sector locally, nationally and internationally. Therefore, patent protection of the present invention is crucial to consolidate it as a more efficient and safer alternative to the options that currently exist. OBJECT OF THE INVENTION An object of the invention is to propose a lipid-based formulation that increases the penetration of topical ophthalmic anesthetics into the eyeball. DESCRIPTION OF THE INVENTION Additional objects and advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following detailed description is only exemplary and explanatory and does not limit the invention as claimed. In order that the present invention may be more easily understood, certain terms are defined.Other definitions are established throughout the description of the embodiments. The present invention relates to a lipid-based formulation that increases the penetration into the eyeball of ophthalmic topical anesthetics, where said formulation comprises: tetracaine (T), polyethylene glycol (PEG)-12 glyceryl dimyristate, ethyl alcohol, polyethylene glycol (15) hydroxystearate (Kolliphor® HS15), anhydrous citric acid and sodium citrate dihydrate. The compositions of the present invention contain an effective amount of tetracaine (T), 0.2 to 10 mg i.e. 0.02 to 10% (w / v), polyethylene glycol (PEG)-12 glyceryl dimyristate, which is used as a structural component of liposomes at a concentration of 5 to 15% (w / v) and ethyl alcohol which is used as an organic solvent at a concentration of 0.7 to 2.1% (v / v). In embodiments of the present invention, the formulation contains polyethylene glycol (15)-hydroxystearate (Kolliphor® HS15) from 2.5 to 7.5% (w / v), as a non-ionic solubilizer and emulsifying agent. This compound is characterized by being of low toxicity and also acts as a permeability enhancer, because it promotes the transport of molecules through cell membranes; increasing the rate of endocytosis and stimulating the translocation of drugs through the paracellular route. The aqueous compositions of the present invention optionally comprise more excipients selected from the group consisting of buffering agents, pH adjusting agents and preservatives. Anhydrous citric acid (0.04 to 0.16%) and sodium citrate dihydrate (0.23 to 0.69%) are used as buffers. The lipid-based compositions of the present invention can be prepared by conventional methods for preparing pharmaceutical compositions in suspension. PREPARATION METHOD. According to the preferred method, tetracaine (T) powder or solution (concentration of 0.2 to 10 mg) is first added to a lipid mixture containing polyethylene glycol (PEG)-12 glyceryl dimyristate (5-15%), polyethylene glycol (15)-hydroxystearate (Kolliphor® HS15) 2.5 to 7.5% and ethyl alcohol (0.7 to 2.1%), combining the components by stirring for 10 minutes ^1 minute at 25 ºC^ 1 ºC. On the other hand, an aqueous base mixture composed of purified water grade 2 (QS), anhydrous citric acid (0.04 to 0.16%) and sodium citrate dihydrate (0.23 to 0.69%) is prepared by combining the components by stirring for 10 minutes ^1 minute at 25 ºC^1 ºC. The aqueous mixture is added to the lipid mixture at room temperature and stirred for 5 min ^ 1 minute to obtain the final formulation. RESULTING FORMULATION. The resulting lipid-based formulation (T-LF) object of this invention is formed as follows: Formulation T-LF Component Quantity Tetracaine 0.2 to 50 mg i.e. 0.02 to 5% (w / v) Polyethylene glycol (15)-hydroxystearate 2.5 to 7.5% (w / v) Polyethylene glycol (PEG)-12 glyceryl dimyristate 5-15% (w / v) Ethyl alcohol 0.7 to 2.1% (v / v) Anhydrous citric acid 0.04 to 0.16% Sodium citrate dihydrate 0.23 to 0.69% Purified water grade 2 QS1.0 ml T-LF; Tetracaine-loaded liposome formulation, (w / v); weight volume, (v / v) volume / volume. Example. The following example is intended to illustrate, but not to limit the present invention [ingredient concentrations are presented in units of % weight / volume (% w / v) or % volume / volume (% v / v)]. The final concentration of tetracaine in the resulting nano suspension in the example is 5 mg / ml (0.5%). The composition of the 0.5% tetracaine-loaded liposome formulation, hereinafter T-LF, is described below. Reagent Volume / Amount Tetracaine 5 mg Polyethylene glycol (15)-hydroxystearate 75 mg Polyethylene glycol (PEG)-12 glyceryl dimyristate 100 mg Ethyl alcohol 14µl Anhydrous citric acid 0.8 mg Sodium citrate dihydrate 4.675 mg Benzalkonium Chloride 0.1 mg Purified Water Grade 2 QS1.0 ml ANALYSIS OF THE RESULTING FORMULATION. The pH of T-LF was analyzed by a potentiometer in triplicate at room temperature. Osmolarity was measured by a vapor pressure osmometer in triplicate at 33°C (the ocular surface temperature). Viscosity was also measured in triplicate at 33°C. Viscosity was measured using a thermostatically controlled rheometer when steady state was reached with shear rates increasing from 0 to 1000 s-1. The particle size of the liposomes contained in T-LF was analyzed by dynamic light scattering, and the zeta potential (ζ) was calculated by measuring the particle velocity using a laser Doppler velocimeter at 25°C (Zetasizer Nano ZS, Malvern Instruments, Malvern, UK). The particle size distribution (Z-mean diameter) and the polydispersity index (PDI) were calculated.The pH of T-LF was 6.3. The physiological pH range of tears is between 6.5 and 7.6. Furthermore, the viscosity of T-LF was 65 cP (high), which could favor its permanence on the ocular surface. The osmolarity was 372 mOsmol / L. The average particle diameter (z-average) was 120 nm, while its PDI was 0.544. To evaluate the stability of T-LF, a thermal stress test was performed. T-LF samples were maintained at 30°C, 40°C, and 60°C for three weeks. The pH and encapsulation efficiency were evaluated on days 0 (baseline), 7, 14, and 21 of thermal incubation. To evaluate the encapsulation efficiency, we measured the T concentration in the filtered solution obtained after T-LF was extruded through a 0.22 μm polycarbonate membrane. The tetracaine concentration in T-LF samples was subtracted from the concentration in control samples (liposomal solution without tetracaine).Tetracaine concentration was determined by high performance liquid chromatography (HPLC) using a Varian 920 LC (Aligent Technologies, Santa Clara, CA, USA) with a Zorbax Eclipse Plus C18, 4.6 x 100 mm, 3.5 μm column (Agilent, Santa Clara, CA, USA) at 25°C. Samples (20 μl) were eluted from the column in a mobile phase composed of water:methanol (30:70) at a flow rate of 1 ml / min. Detection was performed at 312 nm. The retention time and detection limit were 7.2 min and 0.001 mg / ml, respectively. The tetracaine standard curve was linear from 0.001 to 0.100 mg / ml (correlation > 0.99). After 21 days of thermal stress, T-LF maintained its pH stability at 30 and 40°C and even improved encapsulation at higher temperatures (60°C). The stability test results are shown below.T-LF STABILITY STUDY RESULTS Parameter Time (days) 30°C 40°C 60°C 0 6.3 6.38 6.35 pH 7 6.35 6.35 6.37 14 6.35 6.35 6.75** 21 6.35 6.39 6.5** Tetracaine 0 0.55 0.62 0.62 Encapsulation (%) 7 0.69* 0.67** 0.61 14 0.68 0.68** 0.62 21 0.61 0.65 0.65 These and other embodiments of the invention can be further illustrated in the following non-limiting examples. EXAMPLE 1: T-LF tolerability assessment In vivo diffusion analysis and tolerability assessment of T-LF were performed in rabbits. Fifteen New Zealand White rabbits (2–2.5 kg each) were acclimatized and housed in clean cages for at least one week before being included in the study. The rabbits were randomly allocated into three groups, named 12 h or 0.5 day, 1 day, and 7 days. One drop of T-LF solution containing 0.5% tetracaine (50 μl) was applied to the right eye 6 times a day to all rabbits.Five rabbits were sacrificed after starting T-LF instillation at 12 h, 1, and 7 days. Another 15 rabbits were divided into three groups similar to those receiving T-LF, each of which received a drop (50 μl) of 0.5% tetracaine aqueous solution (TA) composed of the active ingredient in water for injection. Before tissue collection for determination of T concentration by HPLC, an ocular examination under anesthesia (intramuscular injection of ketamine hydrochloride 30 mg / kg and chlorpromazine hydrochloride 15 mg / kg) was performed in the rabbits exposed to T-LF to assess ocular tolerability to the solution. This evaluation included slit-lamp biomicroscopy, fluorescein staining, direct ophthalmoscope examination of the fundus, and intraocular pressure (IOP) measurement (iCareTonometer i350, Vantaa, Finland). Additionally, the ocular irritability test was evaluated according to the Pharmacopoeia of the United Mexican States.An irritant reaction was considered positive when more than one rabbit presented: corneal ulceration revealed by fluorescein staining, corneal opacity, inflammation of the iris or conjunctiva, and dilation of the conjunctival vessels, especially around the cornea. After enucleation, the conjunctiva, cornea, retina, 150 μl of aqueous humor, and 200 μl of vitreous were collected. Solid tissues were washed in PBS. Tissues were then homogenized with 0.3 ml of acetonitrile (Sigma-Aldrich, Mexico). Each sample was then centrifuged at 15,294 × g for 5 min. The supernatants were evaporated to add 100 μl of methanol. Another centrifugation was performed, and 20 μl of the resulting supernatants were used for H concentration analysis by HPLC. Samples (20 µl) were eluted from the column in a mobile phase composed of water:methanol (30:70) at a flow rate of 1 ml / min. Detection was performed at 312 nm.The retention time and detection limit were 7.2 min and 0.001 mg / ml, respectively. The tetracaine standard curve (T) was linear from 0.001 to 0.100 mg / ml (correlation > 0.99). The results of the tetracaine concentration analyses are shown below. RESULTS OF IN VIVO DIFFUSION STUDY OF TETRACAINE AFTER APPLICATION OF T-LF Time Tetracaine concentration (ng / g) (days) Conjunctiva Cornea Lens Retina 0.5 2985±271 2357.1±445.31 793.3±79.99 1052±89 1 2735±456 3558.5±380.47 782.2±96.84 1177±761 7 2050±296.4 2130.6±488.89 668.3±49.33 1059±54.24 Time Tetracaine concentration (ng / g) (days) Humor Aqueous humor Vitreous 0.5 705.9±73.95 302.6±30.63 1 838.8±62.98 307.6±69.27 7 789.7±98.51 408.8±27.72 Results of in vivo diffusion study of tetracaine after TA application Time Tetracaine concentration (ng / g) (days) Conjunctiva Cornea Lens Retina 0.5 24555 ±181 2469.2±246.31 293.3±49.5 307.2±11.24 1 2635± 201 3259.3±430.27 782.2±55.64 201.7±44.32 7 2885±196.5 1931±194.77 668.3±33.23 289.3±24.12 Tetracaine concentration (ng / g). Humor Aqueous humor Vitreous 0.5 09.4±24.32 100.2±15.12 1 150.2±17.98 102.6±18.29 7 146.9±27.34 130.2±34.29 The concentrations of T in the ocular surface tissues (cornea and conjunctiva) were similar when comparing the liposomal formulation (T-LF) with the aqueous tetracaine solution (TA). However, the concentrations of T in the intraocular tissues, aqueous humor and vitreous, were higher with T-LF, reflecting the ability of the invention to significantly increase the deposition of the anesthetic in the intraocular compartments and tissues. Therefore, the lipid-based formulation comprising the invention increases the penetration of topical ophthalmic anesthetics into the eyeball. On the other hand, no adverse effects, irritation or ulceration of the ocular surface of rabbits exposed to T-LF were observed, suggesting adequate in vivo tolerability of the formulation.In order to further define the invention, the following terms and definitions are provided herein: Definitions "Anesthetizing," as used herein, refers to administering an anesthetic compound (e.g., tetracaine) for the purpose of preventing sensation and / or reducing pain. "Local anesthesia," as used herein, refers to an anesthetic administered near the nerve ending to be anesthetized that diffuses after introduction into the tissue. A local anesthetic is capable of penetrating tissue deep enough to reach nerves and nerve branches. "Tetracaine" (sometimes referred to as "amethocaine") as used herein refers to (2-(dimethylamino)ethyl 4-(butylamino) benzoate) and any salt thereof. Tetracaine HCl refers to the salt HCl of 2-(dimethylamino)ethyl 4-(butylamino) benzoate.The term "safe and effective amount," as used herein, means an amount of an active ingredient or composition high enough to provide the desired benefit, but low enough to avoid serious side effects within the scope of medical judgment. The term "pharmaceutically acceptable," as used herein, means suitable for use in contact with tissues without undue toxicity, irritation, incompatibility, instability, allergic response, and the like. While only certain features of the invention have been illustrated and described herein, many modifications and changes will be apparent to those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all modifications and changes that fall within the true spirit of the invention.

Claims

CLAIMS Having sufficiently described my invention, I consider as a novelty and therefore claim as my exclusive property, the contents of the following clauses: 1.- A lipid-based formulation that increases the penetration of ophthalmic topical anesthetics into the eyeball, characterized in that it comprises a combination of tetracaine (T), polyethylene glycol (PEG)-12 glyceryl dimyristate, ethyl alcohol, polyethylene glycol (15)-hydroxystearate (Kolliphor® HS15), anhydrous citric acid and sodium citrate dihydrate. 2.- The lipid-based formulation that increases the penetration of ophthalmic topical anesthetics into the eyeball according to claim 1, characterized in that it comprises the following percentages: Tetracaine ………………….. 0.2 to 50 mg i.e. 0.02 to 5% (w / v); Polyethylene glycol (15) –hydroxystearate ………………. 2.5 to 7.5% (w / v); Polyethylene glycol (PEG)-12 glyceryl dimyristate……5-15% (w / v); Ethyl alcohol …………….…………..……... 0.7 to 2.1% (v / v); Anhydrous citric acid ………………………………….. 0.04 to 0.16%; Sodium citrate dihydrate …………………………….. 0.23 to 0.69%; Purified water grade 2 ……………………………… QS1.0 ml.

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