Solution of nitrous oxide for the treatment of disease

Abstract

Described herein are methods for treating disease, comprising the administration of a solution of nitrous oxide.

Description

SOLUTION OF NITROUS OXIDE FOR THE TREATMENT OF DISEASECROSS-REFERENCE

[0001] This application claims benefit of U.S. Provisional Application No. 63 / 623,095, filed on January 19, 2024, which is herein incorporated by reference in its entirety.STATEMENT AS TO FEDERALLY SPONSORED RESEARCH

[0002] This invention was made with the support of the United States government under Contract numbers UG3NS127943 and UH3NS127943 by National Institutes of Health (“NIH”).BACKGROUND

[0003] Given the substantial societal concern with opioid therapy and the lack of potent alternate analgesic choices, there is a substantial medical need for new pain medications that can avoid the risks of opioid tolerance, dependence, and withdrawal. In addition, these considerable societal concerns regarding opioid use have led to a general reluctance to use opioids, leading to undertreatment of pain. Hence, novel effective therapies to reduce pain are sorely needed.

[0004] The analgesic properties of inhaled nitrous oxide (N2O) are well known and account for its long-continued, but limited use in this mode of administration. There are a number of substantial barriers to inhaled N2O that have limited the use of this drug, including: 1) poor dosing control; 2) inadvertent exposure of clinical staff and others; and 3) patient resistance. As described herein, non-inhaled administration of N2O via a liquid or other non-gaseous composition avoids many of the delivery issues associated with iN2O and provides the potential for substantially expanded therapeutic uses of N2O.SUMMARY OF THE INVENTION

[0005] In one aspect, described herein is a method of treating a disease or condition treatable by nitrous oxide in a subject, comprising enterally administering to the subject a therapeutically effective amount of a nitrous oxide (N2O) pharmaceutical composition comprising dissolved gaseous N2O as monotherapy. In some embodiments, described herein is a method of treating a disease or condition treatable by nitrous oxide in a subject, comprising enterally administering to the subject a therapeutically effective amount of a nitrous oxide (N2O) pharmaceutical composition comprising dissolved gaseous N2O as monotherapy in doses 100 times lower than the inhaled form and an expected improved safety margin.

[0006] In some embodiments, the disease or condition treatable by the enterally administered N2O pharmaceutical composition is selected from pain, anxiety, depression, and mood disorders, singly or in combination. In some embodiments, the disease or condition treatable by theenterally administered N2O pharmaceutical composition is pain. In some embodiments, the pain is acute pain or breakthrough pain in a chronic pain condition. In some embodiments, the pain is associated with vaso-occlusive crisis (VOC). In some embodiments, the pain is associated with sickle cell disease (SCD). In some embodiments, the pain is dental pain, bum pain, dressing changes, obstetric labor analgesia, painful procedures, procedures associated with traumatic injury, allergic pain, or ureteric colic. In some embodiments, the pain is chronic pain. In some embodiments, the pain is selected from neuropathic pain, neuralgia, cancer pain, osteo-arthritic pain, traumatic pain, and inflammatory pain. In some embodiments, the pain is post-operative after a surgical procedure. In some embodiments enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 180 minutes after enteral administration. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.005 mg / L. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 60 minutes after enteral administration. In some embodiments, the peak level of N2O in the subject’s blood is greater than 0.1 mg / L. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are an order of magnitude or more lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, the duration of the treatment effect is longer for the enterally administered N2O pharmaceutical composition than that of an inhaled N2O gaseous composition. In some embodiments, the enterally administered N2O pharmaceutical composition is a liquid, a suspension, a gel, a dispersion, a foam, an emulsion, a colloid, or a cream. In some embodiments, the enterally administered N2O pharmaceutical composition is an N2O liquid pharmaceutical composition. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 250 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O pharmaceutical composition or enterally administered N2O liquid pharmaceutical composition is administered orally. In some embodiments, the N2O liquid pharmaceutical composition is administered one or more times a day. In some embodiments, the N2O liquid pharmaceutical composition is administered once a day. In some embodiments, the N2O liquid pharmaceutical composition is administered for 1 to 14 days. In some embodiments, the N2O liquid pharmaceutical composition is administered for over 14 days. In some embodiments, the N2O liquid pharmaceutical composition is an aqueous pharmaceutical composition. In some embodiments,the N2O aqueous liquid pharmaceutical composition further comprises at least one excipient selected from preservatives, acidifiers, flavoring agents, and coloring agents. In some embodiments, further comprising administration of a second agent. In some embodiments, the second agent is an analgesic. In some embodiments, the analgesic is a nonsteroidal antiinflammatory drug. In some embodiments, the analgesic is an opioid. In some embodiments, when the opioid is administered with the liquid composition comprising dissolved gaseous nitrous oxide, the amount of the opioid administered is less than when the opioid is administered without the liquid composition comprising dissolved gaseous nitrous oxide. In some embodiments, the second agent is a vitamin. In some embodiments, the second agent is vitamin B12. In some embodiments, the second agent is a nutrient.INCORPORATION BY REFERENCE

[0007] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the extent applicable and relevant and to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.BRIEF DESCRIPTION OF THE FIGURES

[0008] Fig. 1A. Illustrates the N2O levels in the blood following oral administration of a liquid N2O composition (single dose, lOpl / g body weight by oral gavage at t=0 in Sprague Dawley rats, N=3 per group).

[0009] Fig. IB Illustrates the N2O Cmax in rats orally administered a liquid N2O composition versus the N2O Cmax in rats administered inhaled N2O.

[0010] Fig. 2A. Illustrates the anti -nociceptive efficacy in a mechanical hyperalgesia study following a single oral administration of a liquid N2O composition or vehicle control in normal mice, wherein * indicates a significant difference from baseline (BL) and # indicates a significant difference between groups.

[0011] Fig. 2B Illustrates the anti -nociceptive efficacy in a mechanical hyperalgesia study following a single oral administration of a liquid N2O composition (5 pl / g) or vehicle control (5 pl / g) in Sickle Cell Disease (SCD) mice, wherein * indicates a significant difference from baseline (BL) and # indicates a significant difference between groups.

[0012] Fig. 2C. Illustrates the dose dependency of the anti -nociceptive efficacy in a mechanical hyperalgesia study following oral administration of a liquid N2O composition or vehicle control in Sickle Cell Disease (SCD) mice at dose volumes of 1, 2.5 and 5 pl / g body weight.

[0013] Fig. 3 Illustrates the anti -nociceptive efficacy in a mechanical hyperalgesia study following a 30 min inhaled administration of gaseous N2O (70% N2O; 30% 02) or room aircontrol in Sickle Cell Disease (SCD) mice, with assessments conducted after ending inhaled dosing.

[0014] Fig. 4A Illustrates the anti -nociceptive efficacy in a heat hyperalgesia study following a single oral administration of a liquid N2O composition or vehicle control in normal mice, wherein * indicates a significant difference from baseline (BL) and # indicates a significant difference between groups.

[0015] Fig. 4B Illustrates the anti -nociceptive efficacy in a heat hyperalgesia study following a single oral administration of a liquid N2O composition or vehicle control in Sickle Cell Disease (SCD) mice, wherein * indicates a significant difference from baseline (BL) and # indicates a significant difference between groups.

[0016] Fig. 5 Illustrates the results of a conditioned place preference test comparing the rewarding properties of N2O in a liquid N2O composition and vehicle control or morphine and control.

[0017] Fig. 6 Illustrates the results of a tolerance test following oral administration of a liquid N2O composition and vehicle control or morphine and vehicle control.

[0018] Fig. 7A. Illustrates the results of a study comparing the sedative properties of a liquid N2O composition, a positive control (clonidine), and vehicle control, wherein * indicates a significant difference from baseline.

[0019] Fig. 7B Illustrates the results of a study comparing the sedative properties of repeated high doses of a liquid N2O composition and vehicle control.

[0020] Fig. 8A. Illustrates the effect of a liquid N2O composition (5 ul / g) or vehicle on response of single wide dynamic range dorsal horn neurons to mechanical von Frey stimulus (15 g for 5 sec) before and at 30 and 60 min after drug administration.

[0021] Fig. 8B. Illustrates the mean (±SEM) number of impulses evoked by mechanical von Frey stimulus (15 g for 5 sec) before and after administration of liquid N2O composition (5 ul / g; N=15) or vehicle (5 ul / g; N=11), wherein * indicates a significant difference from baseline.DETAILED DESCRIPTION OF THE INVENTION

[0022] The analgesic properties of nitrous oxide (N2O) are well known, and inhaled N2O (iN2O) has been used for analgesia for over 150 years. The analgesic mechanisms of N2O are complex and not fully understood, but substantial research has been conducted to elucidate these mechanisms. N2O has been reported to act on one or more super-families of ligand-gated ion channels causing multilevel blockade of the ascending and descending pain pathways, reducing receptivity to nociceptive inputs. First, N2O has been shown to non-competitively inhibit N- methyl-D-aspartate (NMD A) receptors (NMD AR). As an NMDA receptor antagonist, N2Oproduces analgesia at sub-anesthetic concentrations and reduces surgical pain. Second, N2O is also understood to act supra-spinally to induce analgesia by facilitating the release of endogenous opioid peptides in the periaqueductal brainstem. This, in turn, activates the descending noradrenergic inhibitory pathway via GABA, reducing nociception at the spinal cord level. Importantly, N2O does not directly target opioid receptors, but rather endogenous opioid peptide release by opioidergic neurons is reported to activate this pathway.

[0023] Although N2O has been demonstrated to be an effective analgesic, there are a number of substantial barriers to i N2O use that have limited the use of this drug. These barriers include: 1) poor dosing control; 2) inadvertent exposure; and 3) patient resistance. Dosing medical gases with a mask has been shown to be inaccurate due to such factors as equipment leakage due to poorly fitted masks, variability in patient ventilation, and variability in pulmonary absorption associated with the variable capacity of the lung. In addition, by-stander inadvertent exposure to i N2O can occur due to leaking or incorrectly operated compressed gas cylinders and leaking inhalation equipment. This is a recognized risk, and occupational exposure limits have been set in the U.S. as well as other countries. Moreover, patient compliance with gas therapies can be problematic due to issues with mask and cannula use.

[0024] In addition, iN2O when inhaled repeatedly over days to weeks, is associated with serious hematological and neurological sequelae associated with interference with vitamin B12 metabolism.

[0025] In addition, i N2O is associated with rapid excretion by exhalation after cessation of breathing the gas. The literature indicates that the half-life of N2O upon cessation of breathing N2O gas is on the order of several minutes (Munson, 1978). This very short half-life is a substantial limitation of ilS O therapeutic use.

[0026] Non-inhaled administration of N2O via a liquid avoids many of the delivery issues associated with ilS O. An IS O-containing liquid allows precise dosing, avoids the safety issues associated with compressed gas cylinders, and avoids the issues of compliance associated with inhaled gas therapies. In addition, the duration of the effect of N2O delivered via oral liquid is unexpectedly and advantageously much longer than that of i N2O after dosing. This provides the potential for substantially expanded uses of N2O, including as an analgesic. This is especially beneficial for home self-administered use, where orally delivered drugs are heavily favored.Certain Terminology

[0027] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which the claimed subject matter belongs. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of any subjectmatter claimed. In this application, the use of the singular includes the plural unless specifically stated otherwise. It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. In this application, the use of “or” means “and / or” unless stated otherwise. Furthermore, use of the term “including” as well as other forms, such as “include”, “includes,” and “included,” is not limiting. The term "comprising" (and related terms such as "comprise" or "comprises" or "having" or "including") is not intended to exclude that in other certain embodiments, for example, an embodiment of any composition of matter, composition, method, or process, or the like, described herein, may "consist of or "consist essentially of' the described features. The term "about" when referring to a number or a numerical range means that the number or numerical range referred to is an approximation within experimental variability (or within statistical experimental error), and thus the number or numerical range may vary between 1% and 15% of the stated number or numerical range.

[0028] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. All documents, or portions of documents, cited in the application including, but not limited to, patents, patent applications, articles, books, manuals, and treatises are hereby expressly incorporated by reference in their entirety.

[0029] The term “acceptable” or “pharmaceutically acceptable”, with respect to a formulation, composition or ingredient, as used herein, means having no persistent detrimental effect on the general health of the subject being treated or does not abrogate the biological activity or properties of the compound, and is relatively nontoxic.

[0030] “Blood concentration” refers to the concentration in the blood of a subject. It is understood that the blood concentration may vary significantly between subjects, due to variability with respect to metabolism and / or possible interactions with other therapeutic agents. In accordance with one embodiment disclosed herein, the blood concentration may vary from subject to subject. Likewise, values such as maximum blood concentration (Cmax) or time to reach maximum blood concentration (Tmax), or total area under the blood concentration time curve (AUC(o-co)) may vary from subject to subject. Due to this variability, the amount necessary to constitute “a therapeutically effective amount” may vary from subject to subject.

[0031] The terms “co-administration” or the like, as used herein, are meant to encompass administration of the selected therapeutic agents to a single patient, and are intended to include treatment regimens in which the agents are administered by the same or different route of administration or at the same or different time.

[0032] The terms “effective amount” or “therapeutically effective amount,” as used herein, refer to a sufficient amount of an agent or a compound being administered which will relieve tosome extent one or more of the symptoms of the disease or condition being treated. The result can be reduction and / or alleviation of the signs, symptoms, or causes of a disease, or any other desired alteration of a biological system. For example, an “effective amount” for therapeutic uses is the amount of the composition including a compound as disclosed herein required to provide a clinically significant decrease in disease symptoms without undue adverse side effects. An appropriate “effective amount” in any individual case may be determined using techniques, such as a dose escalation study. The term “therapeutically effective amount” includes, for example, a prophylactically effective amount. An “effective amount” of a compound disclosed herein is an amount effective to achieve a desired pharmacologic effect or therapeutic improvement without undue adverse side effects. It is understood that “an effect amount” or “a therapeutically effective amount” can vary from subject to subject, due to variation in age, weight, general condition of the subject, the condition being treated, the severity of the condition being treated, and the judgment of the prescribing physician. By way of example only, therapeutically effective amounts may be determined by a dose escalation clinical trial.

[0033] The terms “enhance” or “enhancing” means to increase or prolong either in potency or duration a desired effect. By way of example, “enhancing” the effect of therapeutic agents refers to the ability to increase or prolong, either in potency or duration, the effect of therapeutic agents on treatment of a disease, disorder, or condition. An “enhancing-effective amount,” as used herein, refers to an amount adequate to enhance the effect of a therapeutic agent in the treatment of a disease, disorder, or condition. When used in a patient, amounts effective for this use will depend on the severity and course of the disease, disorder, or condition, previous therapy, the patient's health status and response to the drugs, and the judgment of the treating physician.

[0034] The term “nutrient”, as used herein, refers to a chemical compound contained in foods, such as protein, fat, carbohydrate, vitamin, mineral, and salts.

[0035] The term “prophylactically effective amount,” as used herein, refers that amount of a composition applied to a patient which will relieve to some extent one or more of the symptoms of a disease, condition or disorder being treated. In such prophylactic applications, such amounts may depend on the patient's state of health, weight, and the like. As an example, one can determine such prophylactically effective amounts by a dose escalation clinical trial.

[0036] As used herein, the terms “subject”, “patient”, or “individual” is used to mean an animal, preferably a mammal, including a human or non-human. The terms individual, patient and subject may be used interchangeably.

[0037] The terms “treat,” “treating” or “treatment”, as used herein, include alleviating, abating or ameliorating a disease or condition symptoms, preventing additional symptoms, ameliorating or preventing the underlying metabolic causes of symptoms, inhibiting the disease or condition,e.g., arresting the development of the disease or condition, relieving the disease or condition, causing regression of the disease or condition, relieving a condition caused by the disease or condition, or stopping the symptoms of the disease or condition. The terms “treat,” “treating” or “treatment”, include, but are not limited to, prophylactic and / or therapeutic treatments.

[0038] As used herein, the term “psi” refers to psig, or pounds per square inch gauge, the pressure relative to atmospheric pressure.Methods

[0039] In some embodiments described herein is a method of treating a disease or condition treatable by nitrous oxide in a subject, comprising enterally administering to the subject a therapeutically effective amount of a nitrous oxide (N2O) pharmaceutical composition comprising dissolved gaseous N2O as monotherapy. In some embodiments, the disease or condition treatable by the enterally administered N2O pharmaceutical composition is selected from pain, anxiety, depression, and mood disorders, singly or in combination.

[0040] In some embodiments, the disease or condition treatable by the enterally administered N2O pharmaceutical composition is pain. In some embodiments, the pain is acute pain. In some embodiments, the pain is breakthrough pain in a chronic pain condition. In some embodiments, the pain is associated with vaso-occlusive crisis (VOC). In some embodiments, the pain is associated with sickle cell disease (SCD). In some embodiments, the pain is dental pain, bum pain, dressing changes, obstetric labor analgesia, painful procedures, procedures associated with traumatic injury, allergic pain, or ureteric colic. In some embodiments, the pain is dental pain. In some embodiments, the pain is burn pain. In some embodiments, the pain is pain from dressing changes. In some embodiments, the pain is obstetric labor analgesia. In some embodiments, the pain is pain from painful procedures. In some embodiments, the pain is pain from venipuncture. In some embodiments, the pain is pain from procedures associated with traumatic injury. In some embodiments, the pain is post-operative after a surgical procedure. In some embodiments, the pain is pain from procedures associated with fracture reduction. In some embodiments, the pain is allergic pain. In some embodiments, the pain is ureteric colic.

[0041] In some embodiments, the disease or condition treatable by the enterally administered N2O pharmaceutical composition is chronic pain. In some embodiments, the chronic pain is selected from neuropathic pain, neuralgia, cancer pain, osteo-arthritic pain, traumatic pain, and inflammatory pain. In some embodiments, the chronic pain is selected from neuropathic pain, neuralgia, cancer pain, osteo-arthritic pain, traumatic pain, post-operative pain, and inflammatory pain. In some embodiments, the chronic pain is neuropathic pain. In some embodiments, the chronic pain is neuralgia. In some embodiments, the chronic pain is cancer pain. In some embodiments, the chronic pain is osteo-arthritic pain. In some embodiments, thechronic pain is traumatic pain. In some embodiments, the chronic pain is inflammatory pain. In some embodiments, the pain is post-operative after a surgical procedure.

[0042] In some embodiments, the disease or condition treatable by the enterally administered N2O pharmaceutical composition is anxiety. In some embodiments, the disease or condition treatable by the enterally administered N2O pharmaceutical composition is depression. In some embodiments, the disease or condition treatable by the enterally administered N2O pharmaceutical composition is mood disorders. In some embodiments, the disease or condition treatable by the enterally administered N2O pharmaceutical composition is a combination of two or more of pain, anxiety, depression, and mood disorders.

[0043] In some embodiments, the enterally administered N2O pharmaceutical composition described herein does not cause sedation. In some embodiments, the enterally administered N2O pharmaceutical composition described herein does not produce analgesic tolerance. In some embodiments, the enterally administered N2O pharmaceutical composition described herein does not block vitamin B 12 metabolism or the impairment of vitamin B 12 metabolism is reduced as compared with inhaled N2O. In some embodiments, the enterally administered N2O pharmaceutical composition described herein does not block vitamin B 12 metabolism or the impairment of vitamin B 12 metabolism is delayed as compared with inhaled N2O.

[0044] In some embodiments described herein enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 240 minutes after enteral administration. In some embodiments described herein enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 210 minutes after enteral administration. In some embodiments described herein enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 180 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 150 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 120 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 105 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 90 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in thesubject’s blood, at about 5 to 75 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 60 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 45 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 120 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 105 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 90 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 75 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 60 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 45 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 120 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 105 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 90 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 75 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 60 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 45 minutes after enteral administration.

[0045] In some embodiments described herein, the enterally administered N2O pharmaceutical composition is administered orally. In some embodiments described herein oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 180 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 150 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 120 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 105 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 90 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 75 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 60 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 45 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 120 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 105 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 90 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 75 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 60 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 10 to 45 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 120 minutes after oraladministration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 105 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 90 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 75 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 60 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 15 to 45 minutes after oral administration.

[0046] In some embodiments described herein, the measurable level of N2O in the subject’s blood is at least 0.001 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.002 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.003 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.004 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.005 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.006 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.007 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.008 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.009 mg / L. In some embodiments, the measurable level of N2O in the subject’s blood is at least 0.01 mg / L.

[0047] In some embodiments described herein, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 5 to 90 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 5 to 75 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 5 to 60 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 5 to 45 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 to 90 minutes after enteral administration. In some embodiments, enteral administration of the N2Opharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 to 75 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 to 60 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 to 45 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 90 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 75 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 60 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 45 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 20 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 25 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 30 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 35 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 40 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 45 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 50 minutes after enteral administration. In someembodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 55 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 60 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 75 minutes after enteral administration. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 90 minutes after enteral administration.

[0048] In some embodiments described herein, the enterally administered N2O pharmaceutical composition is administered orally. In some embodiments described herein, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 5 to 90 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 5 to 75 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 5 to 60 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 5 to 45 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 to 90 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 to 75 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 to 60 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 to 45 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 90 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 75 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 60 minutes after oral administration. In some embodiments, oral administration of the N2Opharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 45 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 10 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 20 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 25 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 30 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 35 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 40 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 45 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 50 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 55 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 60 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 75 minutes after oral administration. In some embodiments, oral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 90 minutes after oral administration.

[0049] In some embodiments described herein, the peak level of N2O in the subject’s blood is greater than 0.05 mg / L. In some embodiments, the peak level of N2O in the subject’s blood is greater than 0.01 mg / L. In some embodiments, the peak level of N2O in the subject’s blood is greater than 0.015 mg / L. In some embodiments, the peak level of N2O in the subject’s blood is greater than 0.02 mg / L.

[0050] In some embodiments described herein, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’sblood that are an order of magnitude or more lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are an order of magnitude lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are at least ten times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are at least nine times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are at least eight times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are at least seven times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are at least six times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are at least five times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are ten times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are nine times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are eight times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are seven times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2Opharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are six times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O. In some embodiments, enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are five times lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O.

[0051] In some embodiments described herein, the duration of the treatment effect is longer for the enterally administered N2O pharmaceutical composition than that of an inhaled N2O gaseous composition. In some embodiments described herein, the duration of the treatment effect is longer for the enterally administered N2O pharmaceutical composition than that of an inhaled N2O gaseous composition, wherein the enterally administered N2O pharmaceutical composition is orally administered.

[0052] In some embodiments described herein, the enterally administered N2O pharmaceutical composition is a liquid, a suspension, a gel, a dispersion, a foam, an emulsion, a colloid, or a cream. In some embodiments, the enterally administered N2O pharmaceutical composition is a liquid. In some embodiments, the enterally administered N2O pharmaceutical composition is a suspension. In some embodiments, the enterally administered N2O pharmaceutical composition is a gel. In some embodiments, the enterally administered N2O pharmaceutical composition is a dispersion. In some embodiments, the enterally administered N2O pharmaceutical composition is a foam. In some embodiments, the enterally administered N2O pharmaceutical composition is an emulsion. In some embodiments, the enterally administered N2O pharmaceutical composition is a colloid. In some embodiments, the enterally administered N2O pharmaceutical composition is a cream.

[0053] In some embodiments described herein, the enterally administered N2O pharmaceutical composition is an N2O liquid pharmaceutical composition. In some embodiments described herein, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of over 500 psi. In some embodiments described herein, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 1000 psi and at a temperature of 0°C to 25°C. In some embodiments described herein, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 750 psi and at a temperature of 0°C to 25°C. In some embodiments described herein, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 450 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceuticalcomposition is produced at a pressure of 30 psi to 400 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 350 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 300 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 250 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 450 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 400 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 350 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 300 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 250 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 500 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 450 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 400 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 350 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 300 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 250 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 500 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 450 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 400 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2Oliquid pharmaceutical composition is produced at a pressure of 50 psi to 350 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 300 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 250 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 450 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 400 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 350 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 300 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 250 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 500 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 450 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 400 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 350 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 300 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 250 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 500 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 450 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 400 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 350 psi and at a temperature of 1°C to 8°C. In some embodiments, theenterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 300 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 250 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 450 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 400 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 350 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 300 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 250 psi and at a temperature of 0°C to 25°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 500 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 450 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 400 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 350 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 300 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 250 psi and at a temperature of 0°C to 15°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 500 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 450 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 400 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 350 psi and at a temperature of 1°C to 8°C. In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 300 psi and at a temperature of 1°C to 8°C.In some embodiments, the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 250 psi and at a temperature of 1°C to 8°C.

[0054] In some embodiments described herein, the enterally administered N2O pharmaceutical composition is an N2O liquid pharmaceutical composition, wherein the enterally administered N2O pharmaceutical composition is orally administered. In some embodiments described herein, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 450 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 400 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 350 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 300 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 30 psi to 250 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 450 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 400 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 350 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 300 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 250 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 500 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 450 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 400 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 350 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceuticalcomposition is produced at a pressure of 50 psi to 300 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 250 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 500 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 450 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 400 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 350 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 300 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 250 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 450 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 400 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 350 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 300 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 250 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 500 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 450 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 400 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 350 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 300 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at apressure of 75 psi to 250 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 500 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 450 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 400 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 350 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 300 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 75 psi to 250 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 500 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 450 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 400 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 350 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 300 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 250 psi and at a temperature of 0°C to 25°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 500 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 450 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 400 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 350 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 300 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 250 psi and at a temperature of 0°C to 15°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 500 psi and at atemperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 450 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 400 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 350 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 300 psi and at a temperature of 1°C to 8°C. In some embodiments, the orally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 250 psi and at a temperature of 1°C to 8°C.

[0055] In some embodiments described herein, the enterally administered N2O pharmaceutical composition is administered orally, rectally, through a nasogastric (NG) tube, through a nasointestinal (NI) tube, through a percutaneous endoscopic gastrostomy (PEG) tube, or through a percutaneous intestinal (PI) tube. In some embodiments, the enterally administered N2O pharmaceutical composition is administered orally. In some embodiments, the enterally administered N2O pharmaceutical composition is administered rectally. In some embodiments, the enterally administered N2O pharmaceutical composition is administered through a nasogastric (NG) tube. In some embodiments, the enterally administered N2O pharmaceutical composition is administered through a nasointestinal (NI) tube. In some embodiments, the enterally administered N2O pharmaceutical composition is administered through a percutaneous endoscopic gastrostomy (PEG) tube. In some embodiments, the enterally administered N2O pharmaceutical composition is administered through a percutaneous intestinal (PI) tube.

[0056] In some embodiments described herein, the N2O pharmaceutical composition is administered one or more times a day. In some embodiments, the N2O pharmaceutical composition is administered once a day. In some embodiments, the N2O pharmaceutical composition is administered twice a day. In some embodiments, the N2O pharmaceutical composition is administered three times a day. In some embodiments, the N2O pharmaceutical composition is administered four times a day. In some embodiments, the N2O pharmaceutical composition is administered six times a day. In some embodiments, the N2O pharmaceutical composition is administered eight times a day.

[0057] In some embodiments, the N2O pharmaceutical composition is administered for more than 14 days. In some embodiments, the N2O pharmaceutical composition is administered for 1 to 14 days. In some embodiments, the N2O liquid pharmaceutical composition is administered for 1 to 10 days. In some embodiments, the N2O pharmaceutical composition is administered for1 to 7 days. In some embodiments, the N2O pharmaceutical composition is administered for 1 to 3 days. In some embodiments, the N2O pharmaceutical composition is administered for 1 day.

[0058] In some embodiments described herein, the N2O pharmaceutical composition is administered one or more times a day, wherein the N2O pharmaceutical composition is a liquid pharmaceutical composition. In some embodiments, the N2O liquid pharmaceutical composition is administered one or more times a day. In some embodiments, the N2O liquid pharmaceutical composition is administered once a day. In some embodiments, the N2O liquid pharmaceutical composition is administered twice a day. In some embodiments, the N2O liquid pharmaceutical composition is administered three times a day. In some embodiments, the N2O liquid pharmaceutical composition is administered four times a day. . In some embodiments, the N2O liquid pharmaceutical composition is administered six times a day. In some embodiments, the N2O liquid pharmaceutical composition is administered eight times a day.

[0059] In some embodiments, the N2O liquid pharmaceutical composition is administered for over 14 days. In some embodiments, the N2O liquid pharmaceutical composition is administered for 1 to 14 days. In some embodiments, the N2O liquid pharmaceutical composition is administered for 1 to 10 days. In some embodiments, the N2O liquid pharmaceutical composition is administered for 1 to 7 days. In some embodiments, the N2O liquid pharmaceutical composition is administered for 1 to 3 days. In some embodiments, the N2O liquid pharmaceutical composition is administered for 1 day.

[0060] In some embodiments, the N2O liquid pharmaceutical composition is an aqueous pharmaceutical composition. In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one excipient selected from preservatives, acidifiers, flavoring agents, and coloring agents.

[0061] In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one preservative. In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one preservative selected from potassium sorbate, sodium benzoate, sorbates, benzoic acid, sodium benzoate, benzoates, sulfur dioxide, sulfites, nitrites, nitrates, lactic acid, propionic acid, sodium propionate, calcium propionate, ascorbic acid, sodium ascorbate, butylated hydroxytoluene, butylated hydroxyanisole, gallic acid, sodium gallate, sulfur dioxide, sulfites, tocopherols (Vitamin E), citric acid, sodium citrate, butylated hydroxy anisol (BHA), butylated hydroxyl toluene (BHT), tert-butylhydroquinone (TBHQ), vinegar, sugar, and sodium chloride. In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one preservative selected from potassium sorbate and sodium benzoate.

[0062] In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one acidifier. In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one acidifier selected from acetic acid, adipic acid, calcium acetate, citric acid, sodium citrate, gluconic acid, lactic acid, tartaric acid, malic acid, phosphoric acid, fumaric acid, ascorbic acid (Vitamin C), sorbic acid, propionic acid, hydrochloric acid, and sulfuric acid. In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one acidifier selected from phosphoric acid, citric acid, and sodium citrate.

[0063] In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one flavoring agent. In some embodiments, the N2O aqueous liquid pharmaceutical composition further comprises at least one coloring agent.

[0064] In some embodiments described herein is a method of treating a disease or condition treatable by nitrous oxide in a subject, comprising enterally administering to the subject a therapeutically effective amount of a nitrous oxide (N2O) pharmaceutical composition comprising dissolved gaseous N2O, further comprising administration of a second agent. In some embodiments, the second agent is an analgesic. In some embodiments, the analgesic is a nonsteroidal anti-inflammatory drug. In some embodiments, the analgesic is an opioid. In some embodiments, when the opioid is administered with a liquid composition comprising dissolved gaseous nitrous oxide, the amount of the opioid administered is less than when the opioid is administered without the liquid composition comprising dissolved gaseous nitrous oxide. In some embodiments, the second agent is a vitamin. In some embodiments, the second agent is a multivitamin. In some embodiments, the second agent is vitamin B 12. In some embodiments, the second agent is a nutrient.EXAMPLESExample 1: Preparation of Liquid N2O Composition

[0065] To prepare the liquid N2O composition for the in vivo studies, liquid vehicle containing water at 2°C was exposed to N2O gas at 125 psi and filled into bottles.Example 2: Pharmacokinetic Profile of Liquid N2O Composition Dosed in Normal Rats

[0066] Sprague Dawley rats were used in this study. Body weights were measured on Day -1, during acclimation for randomization to obtain similar average body weight between groups. Groups 1 and 2 were conducted on DO, and Group 3 and 4 were conducted on the following day. Group assignment will be performed per the following table:

[0067] The test articles were administered, and blood collections performed as follows:Groups 1-3 (liquid N2O composition):Groups 1-3 (liquid N2O composition) received a single PO dose at T=0. The dose volume was between 2.5-10 uL / g.A resting (baseline) blood sample (0.4 mL) was taken prior to oral dosing with liquid N2O composition. Following dosing with liquid N2O composition, blood samples were taken at 15, 30, 60, 120 min. Between sampling time points animals were placed in their normal housing cage and monitored for behavior and well-being. Blood (0.4 mL) was collected into heparinized syringes, placed on wet ice for analysis of N2O.Group 4 (Inhaled N2O):Group 4 animals were placed in an anesthesia chamber attached to a swivel tether system and allowed to rest quietly for 15 min breathing room air.Nitrous Oxide gas (concentration: 70% N2O / 30% 02) was administered at a flow rate of 2 L / min for 30 minutes, followed by return to room air for an additional 15 min. The 70% N2O / 30% O2 was administered as inhaled gas in Plexiglas chamber (inside a fume hood) at a flow rate of 2L / min for 30 minutes. All rats were dosed consecutively with the inhaled N2O. After 30 minutes of N2O exposure and an additional 15 min air exposure in the chamber, each rat was returned to its cage.Blood samples were taken via jugular vein catheter (without disturbing the animal) after 15min of breathing room air, after 30 minutes of breathing N2O / O2, and again at 5min, and 15 min following return to room air. At each time point a sample of 0.4 mL of blood was collected into chilled heparinized syringes for PK analysis at each timepoint into chilled heparinized syringes and placed immediately on wet ice for analysis of N2O.

[0068] As shown in Fig. 1A, oral administration of the liquid N2O composition results in measurable levels of N2O in blood, with peak levels at approximately 15 minutes after oraldosing (single dose, 10 pl / g body weight by oral gavage at t=0 in Sprague Dawley rats, N=3 per group). Significantly, the N2O Cmax in rats orally administered the liquid N2O composition is an order of magnitude or more lower than the N2O Cmax in rats administered inhaled N2O (Fig. IB)Example 3-5: Methods for Mechanical and Heat Stimulation

[0069] Responses evoked by mechanical stimuli were determined using a calibrated von Frey monofilament (26 g) with a bending force of 255 mN. This was applied three times, each for 5 s every 20 s, to the most sensitive area of the RF and the mean number of evoked impulses was determined. Heat stimuli were applied using a feedback-controlled Peltier device (contact area of 1 cm2) that delivered a series of nine heat stimuli from 34 to 50°C (each with a duration of 5 s) in ascending steps of 2°C increments from a base temperature of 32°C. The rise / fall rate for all stimuli was 18°C / s. Stimuli were delivered with an interstimulus interval of 60 s.Mechanical and heat stimuli were applied in the same experiments and heat stimuli always followed mechanical stimulation.Example 3: Mechanical Hyperalgesia Study in Normal and Sickle Cell Disease (SCD)Mice Administered Liquid N2O Composition

[0070] Normal or SCD mice were placed on an elevated mesh platform with perforations of1 cm2and under a clear glass cage. Mechanical withdrawal threshold was determined using calibrated von Frey monofilaments applied to the plantar surface of each hind paw and averaged. Responses evoked by mechanical stimuli were determined using a calibrated von Frey monofilament (26 g) with a bending force of 255 mN. This was applied three times, each for 5 s every 20 s, to the most sensitive area of the RF and the mean number of evoked impulses was determined.

[0071] As shown in Fig. 2A (normal mice) and Fig. 2B (SCD mice), oral administration of the liquid N2O composition, but not vehicle, blocked the development of mechanical hyperalgesia (paw withdrawal threshold (PWT)) produced by cold in both normal and SCD mice. In addition, oral administration of the liquid N2O composition decreased cold-evoked hyperalgesia dose- dependently (Fig. 2C). N2O was orally administered in volumes of 1, 2.5 and 5 pl / g body weight. Vehicle was administered in a volume of 5 pl / g body weight. N=8 per group for up to 90 minutes; n=3 per group for after 90 minutes.Example 4: Mechanical Hyperalgesia Study in Sickle Cell Disease (SCD) MiceAdministered Inhaled N2O Composition

[0072] SCD mice were placed on an elevated mesh platform with perforations of 1 cm2and under a clear glass cage. Mechanical withdrawal threshold was determined using calibrated vonFrey monofilaments applied to the plantar surface of each hind paw and averaged. Responses evoked by mechanical stimuli were determined using a calibrated von Frey monofilament (26 g) with a bending force of 255 mN. This was applied three times, each for 5 s every 20 s, to the most sensitive area of the RF and the mean number of evoked impulses was determined.

[0073] As shown in Fig. 3, anti -nociception of iN2O (70% N2O; 30% O2; 30 min exposure) following cold-evoked hyperalgesia is no different than room air control, with measurement beginning approximately 5 minutes after ending inhaled dosing, whereas oral administration of the liquid N2O composition demonstrated anti -nociceptive efficacy through 90 minutes post dose.Example 5: Heat Hyperalgesia Study in Normal and Sickle Cell Disease (SCD) Mice Administered Liquid N2O Composition

[0074] Sensitivity to heat was determined by measuring paw withdrawal latency (PWL) to radiant heat applied to the center of the plantar surface of each hind paw. Normal or SCD mice were placed on an elevated glass platform and allowed to habituate for 10 min. Heat stimuli were applied using a feedback-controlled Peltier device (contact area of 1 cm2) that delivered a series of nine heat stimuli from 34 to 50°C (each with a duration of 5 s) in ascending steps of 2°C increments from a base temperature of 32°C. The heat stimulus was applied three times on each paw and consecutive applications of radiant heat were separated by at least 3 min.

[0075] The latency of response for each hind paw was defined as the average of the three trials. As shown in Fig. 4A (normal mice) and Fig. 4B (SCD mice), oral administration of the liquid N2O compostion, but not vehicle, blocked the development of heat hyperalgesia produced by cold in both normal and SCD mice.Example 6: Conditioned Place Preference (CPP) Test

[0076] The rewarding properties of N2O and morphine in naive C57 mice were compared. The CPP apparatus consists of two chambers with walls containing either horizontal black lines or black circles (visual stimuli). Mice were given access to the entire compartment for 45 min / day for 5 days before conditioning in order to acclimate to the testing environment. A computer tracked the animal’s location at all times. Baseline measures, where the amount of time spent in each half of the chamber was recorded, were taken one day before conditioning. The study included two groups of mice (10 mice per group): one group of mice received vehicle (liquid formulation without N2O at 5 pl / g body wt., p.o.) and liquid containing N2O (5 pl / g body wt., p.o.), and one group of mice receiving morphine (10 mg / kg, s.c.) and vehicle (at volume equivalent to morphine, s.c.). Conditioning consisted of dosing mice with their assigned test articles once per day for three consecutive days (vehicle in the morning and drug in the afternoon). Directly after dosing, the mice were restricted to the one side of the chamber thatwas paired with vehicle or drug for 30 minutes. On the test day, mice were given access to both compartments and the time spent in each compartment was determined. Morphine, but not N2O, produced place preference. Whereas mice dosed with morphine significantly preferred the side of chamber paired with morphine as compared with vehicle control (p = 0.003), mice dosed with N2O did not show a statistically significant preference as compared with vehicle control (Fig. 5). Example 7: Analgesic Tolerance

[0077] Separate groups of naive C57 mice (N=10 / group) received the liquid N2O composition (5 pl / g) or morphine (5 mg / kg, s.c.) twice per day (morning and afternoon separated by approximately 6 hours) for 9 days. Paw withdrawal threshold (PWT) was determined before (BL) and at 1 hour after the morning administration of the drug on days 1, 3, 6 and 9. Whereas morphine produced analgesic tolerance following 9 days of repeated administration, tolerance was not observed following administration of the liquid N2O composition (Fig. 6).Example 8: Rotarod Test

[0078] The rotarod test assesses motor function and was used to determine if the liquid N2O composition produced sedation or impaired motor coordination. The treadmill was gradually accelerated from 3.75 to 5 rpm, with a maximum cutoff time of 300 s. C57 mice were trained to remain on the treadmill for at least 4 min. On the test day, mice received the liquid N2O composition (20 mg / kg)) or the equivalent volume of the vehicle by gavage. Clonidine, a well- known sedative (5 mg / kg, s.c.), served as a positive control. Testing was done before and at 45, 60 and 90 minutes after drug administration and the time when the mouse fell off the treadmill was recorded and compared between groups. As shown in Fig. 7A, the liquid N2O composition (20 mg / kg) did not produce sedation, defined as a decrease in time spent on the treadmill. However, clonidine (5 mg / kg, s.c.), a positive control, caused a strong sedation / effect on motor coordination.

[0079] In another rotarod experiment, C57 mice received vehicle or the liquid N2O composition at doses of 32 ul / g (12 ul / g, 10 ul / g and 10 ul / g every hour for two hours). The rotarod test was performed before (BL) and at 15 and 30 min after the final drug administration. N=5 per group. As shown in Fig. 7B, repeated administration of high doses of the liquid N2O composition did not affect rotarod performance, i.e., did not cause sedation or impair motor coordination.Example 9: Electrophysiological Recording from Spinal Dorsal Horn Neurons

[0080] Mice were anesthetized with 2.5% isoflurane and given dexamethasone (5 mg / kg, subcutaneously [s.q.]) to reduce swelling and continuous saline (0.2 mL / h, s.q.) to maintain hydration. Respiration rate and blood pressure were monitored continuously. Core body temperature was maintained at 37°C using a feedback-controlled heating pad (PhysitempInstruments, Inc, Clifton, NJ). After removal of hair, an incision in the skin was made over the thoracic and lumbar parts of the vertebral column. A laminectomy was performed to expose the lumbar enlargement at L4-L5, and mice were secured in a spinal frame. Anesthesia was then reduced to 0.8% to 1.2%, and a reservoir around the spinal column was made of vinyl polysiloxane dental impression material (3M ESPE Dental Products, St. Paul, MN) and filled with warm mineral oil. The dura mater was removed, and extracellular recordings from dorsal horn neurons with receptive fields (RFs) located on the plantar surface of the hind paw were obtained using glass microelectrodes (1 mV; Kation Scientific, Minneapolis, MN) that were lowered into the spinal cord in 3-mm steps using a hydraulic microdrive (Kopf, Tujunga, CA). Action potential activity was amplified, audio-monitored, and displayed on a storage oscilloscope. Receptive fields of dorsal horn neurons were searched for by gently stroking the skin and applying mild pressure with the experimenter’s fingers. Once identified, neurons were classified functionally as low threshold, wide dynamic range (WDR), and high threshold (HT) cells using mechanical stimulation of graded intensities (brushing, pressure using a large arterial clip, and pinch with forceps) as described previously. Twenty-six receptive field areas were mapped using suprathreshold von Frey monofilaments, drawn on a schematic of the hind paw, and measured using ImageJ (NIH, Bethesda, MD). Only nociceptive WDR and HT neurons with easily discriminated action potentials were studied. As shown in Fig. 8B, the liquid N2O composition (20 mg / kg) was associated with a significantly reduced number of impulses in neurons as compared to baseline, whereas no significant change in the number of impulses was observed in the neurons of animals following administration of vehicle control (equivalent volume). Fig. 8 A shows representative recordings from neurons in animals dosed with either the liquid N2O composition (20 mg / kg) or vehicle control (equivalent volume).

[0081] The examples and embodiments described herein are for illustrative purposes only and in some embodiments, various modifications or changes are to be included within the purview of disclosure and scope of the appended claims.

Claims

CLAIMSWe Claim:

1. A method of treating a disease or condition treatable by nitrous oxide in a subject, comprising enterally administering to the subject a therapeutically effective amount of a nitrous oxide (N2O) pharmaceutical composition comprising dissolved gaseous N2O as monotherapy.

2. The method of claim 1, wherein the disease or condition treatable by the enterally administered N2O pharmaceutical composition is selected from pain, anxiety, depression, and mood disorders.

3. The method of claim 1 or claim 2, wherein the disease or condition treatable by the enterally administered N2O pharmaceutical composition is pain.

4. The method of claim 3, wherein the pain is acute pain or breakthrough pain in a chronic pain condition.

5. The method of any one of claims 2-4, wherein the pain is associated with vaso-occlusive crisis (VOC).

6. The method of any one of claims 2-5, wherein the pain is associated with sickle cell disease (SCD).

7. The method of any one of claims 2-4, wherein the pain is dental pain, burn pain, dressing changes, obstetric labor analgesia, painful procedures, procedures associated with traumatic injury, allergic pain, or ureteric colic.

8. The method of claim 3, wherein the pain is chronic pain.

9. The method of claim 8, wherein the pain is selected from neuropathic pain, neuralgia, cancer pain, osteo-arthritic pain, traumatic pain, and inflammatory pain.

10. The method of claim 8, wherein the pain is post-operative pain after a surgical procedure.

11. The method of any one of claims 1-10, wherein enteral administration of the N2O pharmaceutical composition to the subject results in measurable levels of N2O in the subject’s blood, at about 5 to 180 minutes after enteral administration.

12. The method of claim 11, wherein the measurable level of N2O in the subject’s blood is at least 0.005 mg / L.

13. The method of any one of claims 1-12, wherein enteral administration of the N2O pharmaceutical composition to the subject results in peak levels of N2O in the subject’s blood at about 15 to 60 minutes after enteral administration.

14. The method of claim 13, wherein the peak level of N2O in the subject’s blood is greater than 0.1 mg / L.

15. The method of any one of claims 1-14, wherein enteral administration of the N2O pharmaceutical composition to the subject results in peak levels (Cmax) of N2O in the subject’s blood that are an order of magnitude or more lower than peak levels (Cmax) of N2O in the blood of subjects administered inhaled N2O.

16. The method of any one of claims 1-15, wherein the duration of the treatment effect is longer for the enterally administered N2O pharmaceutical composition than that of an inhaled N2O gaseous composition.

17. The method of any one of claims 1-16, wherein the enterally administered N2O pharmaceutical composition is a liquid, a suspension, a gel, a dispersion, a foam, an emulsion, a colloid, or a cream.

18. The method of any one of claims 1-17, wherein the enterally administered N2O pharmaceutical composition is an N2O liquid pharmaceutical composition.

19. The method of claim 18, wherein the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 50 psi to 500 psi and at a temperature of 0°C to 25°C.

20. The method of claim 18 or claim 19, wherein the enterally administered N2O liquid pharmaceutical composition is produced at a pressure of 100 psi to 250 psi and at a temperature of 1°C to 8°C.

21. The method of any one of claims 1-20, wherein the enterally administered N2O pharmaceutical composition or enterally administered N2O liquid pharmaceutical composition is administered orally.

22. The method of any one of claims 18-21, wherein the N2O liquid pharmaceutical composition is administered one or more times a day.

23. The method of any one of claims 18-22, wherein the N2O liquid pharmaceutical composition is administered once a day.

24. The method of any one of claims 18-23, wherein the N2O liquid pharmaceutical composition is administered for 1 to 14 days.

25. The method of any one of claims 18-23, wherein the N2O liquid pharmaceutical composition is administered for more than 14 days.

26. The method of any one of claims 18-25, wherein the N2O liquid pharmaceutical composition is an aqueous pharmaceutical composition.

27. The method of claim 26, wherein the N2O aqueous liquid pharmaceutical composition further comprises at least one excipient selected from preservatives, acidifiers, flavoring agents, and coloring agents.

28. The method of any one of claims 1-27, further comprising administration of a second agent.

29. The method of claim 28, wherein the second agent is an analgesic.

30. The method of claim 29, wherein the analgesic is a nonsteroidal anti-inflammatory drug.

31. The method of claim 29, wherein the analgesic is an opioid.

32. The method of claim 31, wherein when the opioid is administered with the liquid composition comprising dissolved gaseous nitrous oxide, the amount of the opioid administered is less than when the opioid is administered without the liquid composition comprising dissolved gaseous nitrous oxide.

33. The method of claim 28, wherein the second agent is a vitamin.

34. The method of claim 28, wherein the second agent is vitamin B 12.

35. The method of claim 28, wherein the second agent is a nutrient.

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