NZ710121B2 - Dosage forms and therapeutic uses of l-4-chlorokynurenine - Google Patents

Abstract

There is provided use of L-4-chlorokynuerine in the manufacture of a medicament for the treatment of depression, wherein a unit dose of the medicament comprises about 50 mg to about 1800 mg of the L-4-chlorokynurenine.

Description

DOSAGE FORMS AND THERAPEUTIC USES OF LCHLOROKYNURENINE CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. ional patent ation serial number 61/849,191, filed January 22, 2013 and titled "DOSAGE FORMS AND THERAPEUTIC USES OF LCHLOROKYNURENINE," the content of which is hereby incorporated by reference in its entirety.

ENT REGARDING FEDERALLY SPONSORED RESEARCH The data presented in this application was supported at least in part by Grant Number 2R44DA018515-02 from the U.S. National Institutes of Health. The government has certain rights in the invention.

FIELD OF THE INVENTION The present invention relates to compositions of Lchlorokynurenine (LCl-KYN) in unit dose form and to the use of these compositions for the ent of neurological ions.

BACKGROUND OF THE INVENTION Glutamic acid is a major excitatory neurotransmitter in the mammalian central nervous system, and it is involved in the regulation of l different pathways. Associations have been reported between excessive endogenous glutamic acid and various neurological disorders, both acute and c, such as cerebral ischemia, epilepsy, amyotrophic lateral sclerosis, Huntington’s disease, Parkinson’s disease and Alzheimer’s disease.

Overactive glutamatergic transmission via yl-D-aspartate (NMDA) receptors (NMDA-R) is known to play a key role in l neurologic conditions, such as neuropathic pain for example. However, direct acting NMDA-R antagonists produce a number of side effects, such as psychosis, which have limited their therapeutic utility. Antagonism of NMDA-Rs can also be achieved through blockade of a modulatory site on the NMDA-R, known as the e B (GlyB) coagonist site. (Reference 8, and citations for this reference and the others cited in this manner are presented below). When compared with classic NMDA-R antagonists, GlyB nists have a much better safety profile and do not cause the adverse side s that are associated with "classic" NMDA-R antagonists. (References 1, 6 and 10).

GlyB antagonists also have been shown to reduce hyperalgesia and allodynia in ex vivo and animal neuropathic pain models, and have fewer side effects than classic NMDA-R antagonists, making them a safer alternative as potential analgesics. See, for example, nce 2.

One of the most potent and specific GlyB antagonists currently known is 7- chlorokynurenic acid (7-Cl-KYNA), which is a synthetic, chlorinated analogue of an nous neuromodulator, kynurenic acid. rokynurenic acid has been shown to prevent excitotoxic and ischemic neuronal damage but like most GlyB antagonists does not cross the blood-brain barrier.

Thus, its clinical use is limited. (References 4 and 9).

In contrast, Lchlorokynurenine, a prodrug of 7-chlorokynurenic acid, readily gains access to the central nervous system (CNS) after administration. (References 3, 5, 11 and 12). L chlorokynurenine is efficiently ted to 7-chlorokynurenic acid within activated astrocytes, (Reference 5) and brain levels of 7-chlorokynurenic acid are increased at sites of neuronal injury or toxic insult as a result of astrocyte activation. (Reference 5) In preclinical studies, Lchlorokynurenine has shown anti-seizure activity in rats.

(Reference 11). The compound also was found to increase the firing rate and burst firing ty of dopaminergic neurons in the brains of rats. ence 7).

Methods for the synthesis of a class of 4,6-disubstituted kynurenines derivatives, including Lchlorokynurenine, and their use as antagonists to the NMDA receptor were described in U.S.

Patent No. 5,547,991 to Palfreyman et al. . Pharmaceutical compositions containing these compounds, and their eutic use also were described.

SUMMARY OF THE INVENTION The invention and various ments are set out in the claims that form part of this patent application. [0011a] In a first aspect there is provided use of lorokynuerine in the manufacture of a medicament for the treatment of sion, wherein a unit dose of the medicament comprises about 50 mg to about 1800 mg of the Lchlorokynurenine.

Without limiting the foregoing, in a preferred aspect, the invention relates to pharmaceutical compositions that per unit dose consist essentially of Lchlorokynurenine in an amount of about 360, 1,080 or 1,440 mg, together with pharmaceutically acceptable ingredients such as carriers and excipients. Another aspect of the invention involves the administration of therapeutically effective amounts of these compounds to treat conditions, disorders and diseases caused by ogical dysfunction.

Another aspect of the invention relates to dosing protocols for the inventive compositions, such as the administration of a daily dose of from 1 to about 14 or from 1 to about 30 days, more preferably from about 7 to about 24 days, and most preferably from about 12 to about 16 days.

Another preferred aspect of the invention relates to compositions and methods for the ent of depression and for the treatment of various types of pain, ing hyperalgesia, by administering a therapeutically effective amount of Lchlorokynurenine.

In another , the invention relates to pharmaceutical compositions and associated therapeutic methods of stering Lchlorokynurenine in an amount that produces plasma levels of 7-chlorokynurenic acid as described in this application. A preferred aspect of the invention relates to the administration of Lchlorokynurenine at a dose sufficient to produce plasma levels of 7- chlorokynurenic acid are in the range of about 15 ng/mL to 550 ng/mL.

Another aspect of the invention relates to combination pharmaceutical product and associated methods that comprise formulations including L-DOPA and the pharmaceutical composition of Lchlorokynurenine described in this application, and to their co-administration, either simultaneously or sequentially at dosages described in the application in order to reduce LDOPA ated esias.

All references cited herein, including patent applications and publications, are incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE DRAWINGS The following figures, which are described below and which are incorporated in and constitute a part of the specification, rate exemplary embodiments ing to the disclosure and are not to be considered limiting of the scope of the invention, for the invention may admit to other equally effective embodiments. The figures are not necessarily to scale, and certain es and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.

Fig. 1 represents the mean (n = 12 or 13) plasma concentrations of Lchlorokynurenine on days 1 and 14 after oral administration of aily doses of L kynurenine.

Fig. 2 represents the mean (n = 12 or 13) plasma concentrations of rokynurenic acid on days 1 and 14 after oral administration of once-daily doses of L chlorokynurenine.

DETAILED DESCRIPTION OF THE INVENTION The invention is bed below, with reference to detailed illustrative embodiments. It will be apparent that the invention may be embodied in a wide variety of forms, some of which may be quite ent from those of the disclosed embodiments. Consequently, the ic structural and functional details disclosed below are merely representative and do not limit the scope of the invention.

In work supported by a grant from the National Institutes of Health, it was shown that L chlorokynurenine (also known as VistaGen AV-101) had potent antihyperalgesic actions in three animal models of peripheral tissue inflammation and nerve injury with no evidence of side effects.

Overall, in animal models, Lchlorokynurenine was well tolerated, and produced no safety or toxicity at doses that produce antihyperalgesic effects in animal models.

The present invention is based on the inventors’ clinical findings that certain doses of L chlorokynurenine are in fact safe and tolerable in humans without substantial side effects or any significant adverse effects. Moreover, it was surprisingly found that at such dosages, subjects reported relief from neuropathic pain, specifically, hyperalgesia pain. The compound is an antihyperalgesic. It was also surprisingly found that a ntial number of subjects in the clinical study ed positive feelings of "well-being" from the administration of Lchlorokynurenine, an indicator of anti-depressive activity, whereas this was not reported by the placebo controls.

The present ion relates to compositions and therapeutic methods to treat various types of neurological disorders, neuropathies (both central and peripheral) and ction such as those caused by: (a) injury and drug toxicities such as result from chemotherapy and iral drugs; (b) es and neurodegenerative disorders such as diabetes, cancer, viral infection, Multiple Sclerosis, spondylitis, polyneuritis, surgery, tion, sy, convulsions, Parkinson’s disease, Huntington’s disease, and Alzheimer’s e and those diseases and conditions involving overactive glutamatergic transmission via N-methyl-D-aspartate ors; and (c) imbalances in neurotransmitters, receptors and signaling ys associated with depression and other atric ers. The ent of pain is expressly contemplated, including but not limited to neurogenic pain, spontaneous pain, allodynia hyperalgesia pain, mechanical hyperalgesia pain and heat hyperalgesia pain. Moreover, the treatment of depression is also explicitly contemplated as an aspect of the present ion.

Definitions: "Consisting essentially of" a specified amount of a pharmaceutically active agent means that there is no additional amount of that agent. The presence of other ingredients, for example, excipients and/or lubricants, and the like, or different pharmaceutically active ingredients in combination is not precluded. For example, the combination of L-DOPA with 4-cholorkynurenine is expressly contemplated, as are other compositions and methods for their administration that include 4- chlorokynurenine plus another active ient that are given either simultaneously or sequentially but in a time frame in which they have substantially the same therapeutic effect as if they had been administered in a single combination pharmaceutical product.

"Pharmaceutical unit dose," "unit dose" or "unit dose form" means a single dose of L chlorokynurenine, which is e of being administered to a subject, and which can be readily handled and packaged, remaining as a physically and chemically stable unit dose.

"Therapeutically effective" means that the amount of Lchlorokynurenine administered and ted to 7-chlorokinurenic acid acts to down-regulate NMDA-R mediated signal transmission that is ient to produce a clinical improvement in neurological function, such as a decrease in neuropathic pain, or an increase in feelings of well-being.

"Without significant adverse effect" means that substantially all patients to whom L chlorokynurenine is administered will have no more than a "mild" adverse event as d by the U.S. Food and Drug Administration (FDA). The FDA defines a "mild adverse event" as an event that is easily ted by the subject, causing minimal discomfort and not interfering with everyday activities. In contrast, a ate adverse event" is an event that is sufficiently discomforting causing it to interfere with normal everyday activities.

Pharmaceutical Compositions: Lchlorokynurenine has been synthesized by the s of Palfreyman et al, U.S.

Patent No. 5,547,991. More recent synthesis processes also have been reported in the medical literature, such as Salituro et al. "Enzyme-Activated Antagonists of the Strychnine-Insensitive Glycine/NMDA Receptor, J. Med. Chem. 7-334,336. Lchlorokynurenine also is available commercially from various sources, including BOC Sciences ey, NY, USA) and Advanced Technology & Industrial Co., Ltd. (Hong Kong, China). Cambridge Major Laboratories (Germantown, WI, USA) manufactured the Lchlorokynurenine used in the clinical study discussed in this patent application.

A preferred ment of the invention relates to pharmaceutical compositions sing a unit dose of a therapeutically effective amount of Lchlorokynurenine that is formulated for oral administration, er with pharmaceutically acceptable carriers and excipients.

A pharmaceutical composition of the invention may be formulated in any pharmaceutical form that contains Lchlorokynurenine according to the invention and that produces a blood plasma level of 7-chlorokynurenic acid as described in this application. It is contemplated that the exact dosages of lorokynurenine to be stered within the ranges described for the present ion are to be safe and effective, and that they produce plasma levels of 7-chlorokynurenic acid resulting from the administration of Lchlorokynurenine as described in this patent application at Fig. 2 and in other places. Thus, plasma ranges of 7-chlorokynurenic acid from about 15 ng/mL to about 65 ng/m, from about 65 ng/mL to about 300 ng/mL and from about 300 ng/mL to about 550 ng/mL are expressly contemplated. It is also contemplated that the unit dose formulation of the present invention may be administered one or more times per day, in order to extend the time period in which 4-cholokynurenine levels are elevated to a therapeutically effective amount of 7- cholokynurenic acid.

The unit dose pharmaceutical compositions of Lchlorokynurenine for oral administration preferably contain about 50 mg to about 1,800 mg, more preferably about 260 mg to about 1,540 mg, more ably either about 260 mg to about 460 mg, about 310 mg to about 410 mg, about 980 mg to about 1,180 mg, about 1,030 mg to about 1,130 mg, about 1,340 to about 1,540 mg, about 1,390 mg to about 1,490 mg and most preferably about 360, 1,080 or 1,440 mg.

It is contemplated that the dosing regimens for the compositions of the present invention are eutically effective. While a daily dosing regimen is contemplated, as bed above, this would preferably be from about 5 to about 30 days, including shorter and longer dosing regimes as determined by a patient’s physician. In particular, dosing regimes of about 7 to about 24 days, and about 12 to about 16 days are sly contemplated.

A preferred aspect of the present invention involves the administration of 4- kynurenine in conjunction with L-DOPA to reduce the dyskinesia associated with maintenance doses (typically, determined empirically for each patient by the physician) of L-DOPA; or to reduce the minimum effective dose of L-DOPA, thereby delaying the onset and/or reducing the severity of the dyskinesia. Pharmaceutical compositions according to the present invention may be administered in ation with L-DOPA, concurrently or y enough in al proximity to ameliorate the side effects of L-DOPA administration. Protocols for the stration of L-DOPA are well known as are associated dyskinesias. See, for example, co, N. et al "Clinical Aspects and Management of Levodopa-Induces Dyskinesia," Parkinson’s Disease 2012, Article ID 745947, doi:10.1155/2012/745947.

The pharmaceutical composition according to the present invention may be, for example, a tablet, capsule, liquid suspension, solid solution, softgel, injectable, topical, or transdermal, or suppository and nasal delivery. Additionally, a pharmaceutical composition of the present invention can also be a modified release form such as, but not d to, a al or extended release form.

In general, the pharmaceutical compositions of the invention may be ed by conventional methods know in the art of pharmaceutical formulations. For example, see ton's Pharmaceutical Sciences, 18th Ed., (Mack Publishing Company, Easton, Pa., 1990), which is incorporated herein by reference. In a solid dosage form, Lchlorokynurenine may be d with at least one pharmaceutically acceptable excipient such as, for example, sodium citrate or dicalcium phosphate or (a) fillers or extenders, such as, for example, starches, lactose, sucrose, glucose, mannitol, and silicic acid, (b) binders, such as, for example, cellulose derivatives, starch, alignates, n, polyvinylpyrrolidone, sucrose, and gum acacia, (c) humectants, such as, for example, glycerol, (d) disintegrating agents, such as, for example, agar-agar, calcium carbonate, potato or tapioca , alginic acid, croscarmellose sodium, x tes, and sodium carbonate, (e) solution retarders, such as, for example, paraffin, (f) absorption accelerators, such as, for e, quaternary ammonium compounds, (g) wetting agents, such as, for example, cetyl alcohol, and glycerol monostearate, magnesium stearate and the like (h) adsorbents, such as, for example, kaolin and bentonite, and (i) lubricants, such as, for example, talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, or mixtures f. In the case of capsules, tablets, and pills, the dosage forms may also comprise buffering agents.

Pharmaceutically acceptable nts known in the pharmaceutical formulation art may also be used in the pharmaceutical compositions of the invention. These include, but are not limited to, preserving, wetting, suspending, sweetening, flavoring, perfuming, emulsifying, and dispensing agents. Prevention of the action of microorganisms may be ensured by inclusion of various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, and the like. It may also be desirable to include isotonic agents, for example, sugars, sodium de, and the like. If desired, a ceutical composition of the invention may also contain minor amounts of auxiliary substances such as wetting or emulsifying agents, pH buffering agents, antioxidants, and the like, such as, for example, citric acid, sorbitan monolaurate, triethanolamine oleate, butylated hydroxytoluene, etc.

Solid dosage forms as described above may be prepared with coatings and shells, such as enteric coatings and others well known in the art. They may contain pacifying agents, and can also be of such composition that they release the active compound or compounds in a certain part of the intestinal tract in a delayed manner. miting examples of ed compositions that may be used are polymeric substances and waxes. The active compounds may also be in microencapsulated form, if appropriate, with one or more of the above-mentioned excipients.

Suspensions, in addition to the active compounds, may n suspending agents, such as, for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, rystalline cellulose, aluminum metahydroxide, bentonite, gar and tragacanth, or mixtures of these substances, and the like.

Compositions for rectal strations are, for example, suppositories that may be prepared by mixing the lline genistein sodium salt dihydrate according to the invention with, for example, le non-irritating excipients or carriers such as cocoa butter, polyethylene glycol or a suppository wax, which may be solid at ordinary temperatures but may be liquid at body temperature and, therefore, melt while in a suitable body cavity and release the active component therein.

Clinical Study: A Phase 1b, single-site, randomized, double-blind, placebo-controlled, study was conducted involving multiple oral doses of AV-101 in healthy male and female subjects. Subjects were randomized into one of three cohorts (360, 1,080, and 1,440 mg) and ed a daily oral dose for 14 consecutive days. Each cohort originally included 12 ts on active drug and 4 subjects on placebo. The safety, pharmacokinetics (PK), bility of treatment, and antihyperalgesic effect of AV-101 on capsaicin-induced hyperalgesia were assessed.

The following PK parameters were derived from the plasma tration versus time profiles to determine the single-dose and multiple-dose PK e of AV-101 (Lchlorokynurenine) and the active metabolite, 7-chlorokynurenic acid: Maximum concentration (Cmax), Terminal elimination half-life (t1/2), Time to maximum concentration (Tmax), Area under the plasma study drug concentration versus time curve from Time 0 to time of last measurable concentration (AUC0-t) and Area under the plasma study drug concentration versus time curve from Time 0 extrapolated to infinity (AUC0−∞).

Blood was collected in 6-mL lithium heparin Vacutainer tubes. Samples were fuged, and the plasma was separated from the cells and frozen within 30 minutes after centrifugation.

Centrifuged samples were placed on ice until they were placed in the freezer. Plasma samples were stored frozen at approximately –20°C until their nt to a contractor for analysis.

Baseline samples (0 minutes) were collected before the drug was administered on Day 1 and on Day 14. Samples were then collected at 0.5, 1, 1.5, 2, 4, 6, 8, 12, and 24 hours after dosing on Day 1 and Day 14.

A liquid chromatography with tandem mass ometry assay was used for the determination of rokynurenic acid and Lchlorokynurenine in human plasma. The rd curve range was from 2.00 to 1,000 ng/mL for 7-chlorokynurenic acid, with a lower limit of quantification of 2.00 ng/mL. The standard curve range was from 0.05 to 50 µg/mL for LCl-KYN with a lower limit of quantification of 0.05 µg/mL. Both assays used a plasma sample volume of 50.0 The PK of AV-101 were fully characterized across the range of doses in the study. Plasma concentration-time profiles obtained for Lchlorokynurenine and 7-chlorokynurenic acid after administration of a single and multiple, once daily oral doses of 360, 1,080, or 1,440 mg were consistent with rapid absorption of the oral dose and first-order elimination of both analytes, with evidence of multicompartment kinetics, particularly for the metabolite 7-chlorokynurenic acid. Mean Lchlorokynurenine Tmax values increased with increasing dose level, reaching nearly 2 hours for the highest dose group. Mean t1/2 values were fairly consistent across doses, ranging from 1.64 to 1.82 hours. Mean Lchlorokynurenine Cmax and AUC0-∞ values appeared to be approximately dose linear, although not proportional. Mean Cmax values on Day 1 ranged from 27.7 µg/mL after the 360-mg dose to 64.4 µg/mL after the 1,440-mg dose. Mean AUC0-t values on Day 1 ranged from 64 µg·h/mL after the lowest dose to 196 µg·h/mL after the 1,440-mg dose. Mean Cmax and AUC0-t values the majority of the times were slightly lower on Day 14 than those on Day 1.

In l, as expected for a metabolite, 7-chlorokynurenic acid maximum concentrations occurred at the same time or later than those for Lchlorokynurenine, with mean Tmax values ranging from 1.67 to 2.34 hours. This is shown in Figs. 1 and 2. Mean t1/2 values, ranging from 2.52 to 3.23 hours, were slightly more variable across doses than those for Lchlorokynurenine. Mean t1/2 values did not appear to be dose related. Mean 7-chlorokynurenic acid Cmax and AUC0-t values also appeared to be imately dose linear. Mean Cmax values on Day 1 ranged from 42.7 ng/mL after the 360-mg dose to 314 ng/mL after the 1,440-mg dose. Mean AUC0-t values on Day 1 ranged from 156 ng·h/mL after the lowest dose to 985 ng·h/mL after the 1,440-mg dose. Similar to the parent compound, mean Cmax and AUC0-t values for 7-chlorokynurenic acid generally were ly lower on Day 14 than those on Day 1.

E 1: Antihyperalgesic effect of Lchlorokynurenine on cin-induced hyperalgesia.

On Day 1 and Day 14 of the clinical study, two intradermal injections of 250 µg of capsaicin were injected sequentially into the volar aspect of alternate forearms to produce burning pain, secondary hyperalgesia, and a flare. The cin USP (United States Pharmacopeia) was prepared according to the site’s standard ure and ved in 20% cyclodextrin at a concentration of 10 mg/mL.

The first capsaicin injection in one forearm was given 1 hour after oral administration of AV-101 or placebo, and the second capsaicin injection was given in the other forearm 2 hours after the administration of AV-101 or placebo. The neurosensory testing began immediately at each capsaicin injection. The serial pain assessments using a 100-mm visual analog scale (VAS) occurred at ection and 0, 5, 10, 15, 30, 45, and 60 minutes after each capsaicin injection. The examiner asked the subject to rate the intensity by using the VAS of the spontaneous pain and elicited pain from the application of a 5.18 von Frey hair, 40°C probe, and gentle ng with a 1-inch foam brush.

The VAS consisted of a 100-mm line with "no pain" written at the 0-mm end and the "worst imaginable pain" written at the 100-mm end. The distance in millimeters provided the pain measurement.

The borders of the hyperalgesic area to a 5.18 von Frey hair were determined by moving from an area of the skin that did not produce pain tangentially toward the center of the painful area at a progressively closer radius until the subject reported pain or tenderness. At least eight determinations of the hyperalgesic area borders were made using the same assessments and ng at different angles. Additionally, subjects were asked to rate the pain intensity of a te 45°C heat stimulus (brief thermal stimulation) applied to the anterior thigh at 4.5 hours (±5 minutes) after study drug administration, then every 30 minutes (±5 minutes) through 6 hours after study drug stration. A radiant temperature probe was applied to fix the skin temperature at 36°C during the pain ments. Subjects used the VAS for all pain assessments.

All study ment time points were anchored to Time 0, the time of study drug administration. For the capsaicin injection at 1 hour after dosing, the assessment interval (i.e., time after dosing of the study drug) was 60 to 120 minutes, during which time assessments occurred at approximately 60, 65, 70, and 75 s and then every 15 minutes through the 120-minute time point (i.e., 0, 5, 10, 15, 30, 45, and 60 minutes after capsaicin injection). The second ion of capsaicin was administered approximately 2 hours after dosing of the clinical trial al (CTM), and the assessment interval (i.e., time after dosing of the CTM) was 120 to 180 minutes. The serial pain assessments followed the same schedule, as described after the first capsaicin injection.

The primary efficacy endpoint was the analgesic response to spontaneous pain at each dose level of AV-101 120 to 180 minutes after dosing on Day 14. There was no significant change in the area under the pain time curve (AUPC) for the spontaneous pain assessment between the treatment and the o groups. Likewise, there were no significant changes n the treatment and the o groups for any of the secondary efficacy endpoints (AUPC for spontaneous pain for the time al of 120 to 180 s after dosing on Day 1; and AUPC for spontaneous pain, elicited pain from the von Frey hair, and elicited pain from the 40°C probe for the time interval of 60 to 180 minutes after dosing on Days 1 and 14). r, the present inventors found a consistent decrease in the least squares means of the AUPC for allodynia pain, mechanical hyperalgesia pain, and heat hyperalgesia pain between subjects that received 1,080 mg AV-101 (Cohort 2) and subjects that received placebo. These data are shown in Table 1.

Table 1: Pain evaluation scores Heat Allogesia n MAXPAIN MP StdDiv placebo 4 84.75 5.74 1080 mg 13 78.85 16.22 Mechanical Allogesia n MAXPAIN MP StdDiv placebo 4 79.75 7.93 1080 mg 13 66.23 25.60 Allodynia Pain (foam brush) n MAXPAIN MP StdDiv placebo 4 79.50 9.68 1080 mg 13 70.92 21.63 Spontaneous Pain n MAXPAIN MP StdDiv placebo 4 77.00 10.23 1080 mg 13 75.08 23.33 EXAMPLE 2: Anti-Depressive Activity of Lchlorokynurenine The present inventors singly also found a mood enhancing or anti-depressive activity of Lchlorokynurenine. In the clinical study described in this ation, 5 out of 26 subjects (as contrasted with zero subjects in the placebo group) affirmatively reported feelings of well being. This is consistent with reports that the glutamatergic system contributes to the pathophysiology of depression and that stress can induce changes in NMDA receptors. See, for example, Calabrese et al. s-Induced s of Hippocampal NMDA Receptors: Modulation by Duloxetine Treatment," PLoS ONE 2012, 7(5): e37916. doi:10.1371/journal.pone.0037916.

In summary, the invention described in this application generally relates to dosage forms of Lchlorokynurenine and methods for ng neurological conditions characterized by overactive glutamatergic transmission mediated by N-methyl-D-aspartate receptors, as described above. While certain exemplary embodiments have been described above in detail and shown in the accompanying g figures, it is to be understood that such embodiments are merely rative of and not restrictive of the broad invention. In particular, it should be recognized that the teachings of the invention apply to a wide variety of diseases. Persons of skill in the art will recognize that various modifications may be made to the illustrated and other ments of the invention described above, without departing from its broad inventive scope. Thus, it will be tood that the invention is not limited to the particular embodiments or arrangements disclosed, but is rather intended to cover any s, adaptations or modifications which are within the scope and spirit of the invention as defined by the appended claims.

References: The following journal articles and all other publications, patents and texts mentioned in this application are incorporated by reference in their entireties. (1) Carter AJ. Glycine antagonist: tion of the NMDA receptor channel complex by the strychnine-insensitive glycine site. Drugs Future 1992;17:595-613. (2) i et al., Competitive Gly/NMDA receptor antagonists, Curr. Top. Med. Chem. 2006;6(8):809-21. (3) Hokari M, Wu H-Q, Schwarcz R, Smith QR. Facilitated brain uptake of 4-chlorokynurenine and conversion to 7-chlorokynurenic acid. Neuroreport 1996;8(1):15-18. (4) Kemp JA, Foster AC, Leeson PD, Priestley T, Tridgett R, Iversen LL, et al. 7-Chlorokynurenic acid is a selective antagonist at the e modulatory site of the N-methyl- D-aspartate receptor complex. Proc Natl Acads Sci U.S.A. 1988;85(17):6547-6550. (5) Lee S-C, Schwarcz R. Excitotoxic injury stimulates pro-drug-induced 7-chlorokynurenate formation in the rat striatum in vivo. Neuroscience Lett 04(3):185-188. (6) Leeson PD, Iversen LL. The glycine site on the NMDA receptor: Structure-activity relationships and therapeutic potential. J Med Chem 1994;37(24):4053-4067. (7) Linderholm, et al., Activation of rat l tegmental area dopamine neurons by endogenous kynurenic acid: a pharmacological analysis, Neuropharmacology 2007;53(8):918-924. (8) Parsons CG, Danysz W, Quack G, Hartmann S, Lorenz B, Wollenburg C, et al. Novel ically active antagonists of the e site of the N-methyl-D-aspartate receptor: electrophysiological, biochemical and behavioral terization. J col Exp Ther 1997;283(3):1264-1275. (9) Rao TS, Gray NM, Dappen MS, Cler JA, Mick SJ, Emmett MR, et al. Indole carboxylates, novel antagonists of the N-methyl-D-aspartate (NMDA)-associated glycine recognition sites: in vivo characterization. Neuropharmacol 1993;32(2):139-147. (10) Rundfeldt C, Wlaz P, Loscher W. Anticonvulsant activity of antagonists and partial agonists for the NMDA or-associated glycine site in the kindling model of epilepsy. Brain Res 1994;653(1-2):125-130. (11) Wu HQ, Lee SC, Scharfman HE, cz R. Lchlorokynurenine attenuates kainate-induced seizures and lesions in the rat. Exp Neurol 2002;177(1):222-232. (12) Wu H-Q, Lee S-C, Schwarcz R. Systemic administration of 4-chlorokynurenine prevents quinolinate neurotoxicity in the rat hippocampus. Eur J Pharm 2000;390:267-274.

Claims (5)

We claim:

1. Use of Lchlorokynuerine in the cture of a medicament for the treatment of depression, wherein a unit dose of the medicament comprises about 50 mg to about 1800 mg of the Lchlorokynurenine.

2. The use according to claim 1, wherein the medicament comprises about 360, 1,080 or 1,440 mg lorokynurenine per unit dose.

3. The use according to claim 1 or 2, wherein the medicament r comprises a pharmaceutically acceptable carrier, excipient, or both.

4. The use of any one of claims 1-3, wherein the medicament is formulated for oral administration.

5. The use of any one of claims 1-4, wherein the medicament is to be administered from 1 to about 30 days.