S(+) desmethylselegiline and its use to treat narcolepsy Number:7,144,584 from the United States Patent and Trademark Office (PTO) owispatent The present invention provides novel compositions and methods for using the S(+) enantiomer of desmethylselegiline (N-methyl-N-(prop-2-ynyl)-2-aminophenylpropane), for the treatment of selegiline-responsive diseases and conditions. Diseases and conditions responsive to selegiline include those produced by neuronal degeneration or neuronal trauma and those due to immune system dysfunction. Effective dosages are a daily dose of at least about 0.015 mg/kg of body weight.<H desmethylselegiline, narcolepsy, S, desmethylsele, 7144584.html, Patent, pto, 7144584

Title: S(+) desmethylselegiline and its use to treat narcolepsy

Abstract: The present invention provides novel compositions and methods for using the S(+) enantiomer of desmethylselegiline (N-methyl-N-(prop-2-ynyl)-2-aminophenylpropane), for the treatment of selegiline-responsive diseases and conditions. Diseases and conditions responsive to selegiline include those produced by neuronal degeneration or neuronal trauma and those due to immune system dysfunction. Effective dosages are a daily dose of at least about 0.015 mg/kg of body weight.

Patent Number: 7,144,584 Issued on 12/05/2006 to DiSanto

Inventors: DiSanto; Anthony R. (Dade City, FL)
Assignee: Somerset Pharmaceuticals, Inc. (

Appl. No.: 10/885,221

Filed: July 6, 2004

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
10251727	Sep., 2002	6759053
09800022	Mar., 2001	6455060
09448483	Nov., 1999	6210706
08679328	Jul., 1996	6033682
PCT/US96/01561	Jan., 1996
08372139	Jan., 1995
60011979	Jul., 1995

Current U.S. Class: 424/422 ; 424/434; 424/449; 424/464

Current International Class: A61F 13/00 (20060101); A61K 9/20 (20060101)

Field of Search: 424/464,434,422,447,449 514/923,816

References Cited [Referenced By]

U.S. Patent Documents


4564706	January 1986	Ecsery et al.
4812481	March 1989	Reischig et al.
4861800	August 1989	Buyske
4925878	May 1990	Bodo et al.
5075338	December 1991	Knoll et al.
5128145	July 1992	Edgren et al.
5190763	March 1993	Edgren et al.
5225446	July 1993	Milgram
5234957	August 1993	Mantelle
5242950	September 1993	Fries Hastings
RE34579	April 1994	Buyske et al.
5380761	January 1995	Szabo et al.

Foreign Patent Documents


0 404 807	Jan., 1991	EP
0 509 761	Oct., 1992	EP
0 593 807	Apr., 1994	EP
WO 92/17169	Oct., 1992	WO

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Primary Examiner: Channavajjala; Lakshmi
Attorney, Agent or Firm: Vinson & Elkins LLP

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Ser. No. 10/251,727, filed on Sep. 20, 2002, which issued as U.S. Pat. No. 6,759,053. U.S. Ser. No. 10/251,727 is a continuation of U.S. application Ser. No. 09/800,022, filed on Mar. 5, 2001, which issued as U.S. Pat. No. 6,455,060. U.S. application Ser. No. 09/800,022 is a division of U.S. application Ser. No. 09/448,483, filed on Nov. 24, 1999, which issued as U.S. Pat. No. 6,210,706. U.S. application Ser. No. 09/448,483 is a division of U.S. application Ser. No. 08/679,328, filed on Jul. 12, 1996, which issued as U.S. Pat. No. 6,033,682, and which was a continuation-in-part of PCT/US96/01561, with an international filing date of Jan. 11, 1996, a continuation-in-part of U.S. 60/011,979, filed Jul. 31, 1995, and a continuation-in-part of U.S. 08/372,139, filed Jan. 13, 1995 now abandoned.

Claims

What is claimed is:

1. A method of treating narcolepsy in a subject comprising administering to the subject suffering from narcolepsy S(+)-desmethylselegiline or a pharmaceutically acceptable salt thereof, employing a single or multiple dosage regimen effective to treat the narcolepsy.

2. The method of claim 1, wherein the subject is human.

3. The method of claim 1, wherein the S(+)-desmethylselegiline is in a substantially isomerically pure form.

4. The method of claim 1, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered orally.

5. The method of claim 1, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered non-orally.

6. The method of claim 5, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered transdermally.

7. The method of claim 5, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered parenterally.

8. The method of claim 1, wherein the dosage regimen of S(+)-desmethylselegiline administered to the subject per day is at least about 0.015 mg/kg of the subject's body weight, calculated on the basis of the free secondary amine.

9. The method of claim 5, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered buccally.

10. The method of claim 5, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered sublingually.

11. The method of claim 5, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered intravenously.

12. The method of claim 5, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered subcutaneously.

13. The method of claim 5, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered rectally.

14. The method of claim 5, wherein the S(+)-desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof is administered intra-peritoneally.

15. The method of claim 1, wherein the dosage regimen of S(+)-desmethylselegiline administered to the subject per day is at least about 0.10 mg/kg of the subject's body weight, calculated on the basis of the free secondary amine.

16. The method of claim 1, wherein the dosage regimen of S(+)-desmethylselegiline administered to the subject per day is at least about 1.0 mg/kg of the subject's body weight, calculated on the basis of the free secondary amine.

17. The method of claim 1, wherein the single dosage regimen is employed.

18. The method of claim 1, wherein the multiple dosage regimen is employed.

Description

FIELD OF THE INVENTION

The present invention provides a novel S(+) isomer of desmethylselegiline, i.e., a compound of the formula:

##STR00001## and further provides novel pharmaceutical and other compositions containing this isomer. In addition, the present invention provides novel methods for using this enantiomer in the treatment of selegiline-responsive diseases and conditions in animals, including humans.

BACKGROUND OF THE INVENTION

Two distinct monoamine oxidase enzymes are known in the art: monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B). The cDNAs encoding these enzymes show different promoter regions and distinct exon portions, indicating they are encoded independently at different gene positions. In addition, analysis of the two proteins has shown differences in their respective amino acid sequences.

The first compound found to selectively inhibit MAO-B was R-(-)-N-methyl-N-(prop-2-ynyl)-2-aminophenylpropane, also known as L-(-)-deprenyl, R-(-)-deprenyl, or selegiline. Selegiline has the following structural formula:

##STR00002##

The selectivity of selegiline in the inhibition of MAO-B is important to its safety profile following oral administration. Inhibition of MAO-A may cause toxic side effects by interfering with the metabolism of tyramine. Tyramine is normally metabolized in the gastrointestinal tract by MAO-A but when MAO-A is inhibited, tyramine absorption is increased following consumption of tyramine-containing foods such as cheese, beer, herring, etc. This results in the release of catecholamines which can precipitate a hypertensive crisis, producing the "cheese-effect." This effect is characterized by Goodman and Gilman as the most serious toxic effect associated with MAO-A inhibitors.

One of the metabolites of selegiline is its N-desmethyl analog. Structurally, desmethylselegiline is the R(-) enantiomeric form of a secondary amine of the formula:

##STR00003##

Heretofore, desmethylselegiline was not known to have pharmaceutically useful MAO-related effects, i.e., potent and selective inhibitory effects on MAO-B. In the course of determining the usefulness of desmethylselegiline for the purposes of the present invention, the MAO-related effects of desmethylselegiline were more completely characterized. This characterization has established that desmethylselegiline has exceedingly weak MAO-B inhibitory effects and no advantages in selectivity with respect to MAO-B compared to selegiline.

For example, the present characterization established that selegiline has an IC.sub.50 value against MAO-B in human platelets of 5.times.10.sup.-9 M whereas R(-)desmethylselegiline's IC.sub.50 value is 4.times.10.sup.-7 M, indicating the latter is approximately 80 times less potent as an MAO-B inhibitor than the former. Similar characteristics can be seen in the following data measuring inhibition of MAO-B and MAO-A in rat cortex mitochondrial-rich fractions:

TABLE-US-00001 TABLE 1 Inhibition of MAO by Selegiline and Desmethylselegiline Percent Inhibition selegiline R(-)desmethylselegiline Conc. MAO-B MAO-A MAO-B MAO-A 0.003 .mu.M 16.70 -- 3.40 -- 0.010 .mu.M 40.20 -- 7.50 -- 0.030 .mu.M 64.70 -- 4.60 -- 0.100 .mu.M 91.80 -- 6.70 -- 0.300 .mu.M 94.55 9.75 26.15 0.0 1.000 .mu.M 95.65 32.55 54.73 0.70 3.000 .mu.M 98.10 65.50 86.27 4.10 10.000 .mu.M -- 97.75 95.15 11.75 30.000 .mu.M -- -- 97.05 -- 100.000 .mu.M -- -- -- 56.10

As is apparent from the above table, selegiline is approximately 128 times more potent as an inhibitor of MAO-B relative to MAO-A, whereas desmethylselegiline is about 97 times more potent as an inhibitor of MAO-B relative to MAO-A. Accordingly, desmethylselegiline appears to have an approximately equal selectivity for MAO-B compared to MAO-A as selegiline, albeit with a substantially reduced potency.

Analogous results are obtained in rat brain tissue. Selegiline exhibits an IC.sub.50 for MAO-B of 0.11.times.10.sup.-7 M whereas desmethylselegiline's IC.sub.50 value is 7.3.times.10 .mu.M, indicating desmethylselegiline is approximately 70 times less potent as an MAO-B inhibitor than selegiline. Both compounds exhibit low potency in inhibiting MAO-A in rat brain tissue, 0.18.times.10.sup.-5 for selegiline, 7.0.times.10.sup.-7 for desmethylselegiline. Thus, in vitro R(-)desmethylselegiline is approximately 39 times less potent than selegiline in inhibiting MAO-A.

Based on its pharmacological profile as set forth above, R(-)desmethylselegiline as an MAO-B inhibitor provides no advantages in either potency or selectivity compared to selegiline. To the contrary, the above in vitro data suggest that use of desmethylselegiline as an MAO-B inhibitor requires on the order of 70 times the amount of selegiline.

The potency of desmethylselegiline-as an MAO-B inhibitor in vivo has been reported by Heinonen, E. H., et al. ("Desmethylselegiline, a metabolite of selegiline, is an irreversible inhibitor of MAO-B in human subjects," referenced in Academic Dissertation "Selegiline in the Treatment of Parkinson's Disease," from Research Reports from the Department of Neurology, University of Turku, Turku, Finland, No. 33 (1995), pp. 59 61). According to Heinonen, desmethylselegiline in vivo has only about one-fifth the MAO-B inhibitory effect as selegiline, i.e., a dose of 10 mg of desmethylselegiline would be required for the same MAO-B effect as 1.8 mg of selegiline. In rats, Barbe reported R(-)desmethylselegiline to be an irreversible inhibitor of MAO-B, with a potency about 60 fold lower than selegiline in vitro and about 3 fold lower ex vivo (Barbe, H. O., J. Neural Trans. (Suppl.):32:131 (i990)).

The various diseases and conditions for which selegiline is disclosed as being to be useful include: depression (U.S. Pat. No. 4,861,800); Alzheimer's disease and Parkinson's disease, particularly through the use of transdermal dosage forms, including ointments, creams and patches; macular degeneration (U.S. Pat. No. 5,242,950); age-dependent degeneracies, including renal function and cognitive function as evidenced by spatial learning ability (U.S. Pat. No. 5,151,449); pituitary-dependent Cushing's disease in humans and nonhumans (U.S. Pat. No. 5,192,808); immune system dysfunction in both humans (U.S. Pat. No. 5,387,615) and animals (U.S. Pat. No. 5,276,057); age-dependent weight loss in mammals (U.S. Pat. No. 5,225,446); and schizophrenia (U.S. Pat. No. 5,151,419). PCT Published Application WO 92/17169 discloses the use of selegiline in the treatment of neuromuscular and neurodegenerative disease and in the treatment of CNS injury due to hypoxia, hypoglycemia, ischemic stroke or trauma. In addition, the biochemical effects of selegiline on neuronal cells have been extensively studied. For example, see Tatton, et al., "Selegiline Can Mediate Neuronal Rescue Rather than Neuronal Protection," Movement Disorders 8 (Supp. 1): S20 S30 (1993); Tatton, et al., "Rescue of Dying Neurons," J. Neurosci. Res. 30:666 672 (1991); and Tatton, et al., "(-)-Deprenyl Prevents Mitochondrial Depolarization and Reduces Cell Death in Trophically-Deprived Cells," 11th Int'l Symp. on Parkinson's Disease, Rome, Italy, Mar. 26 30, 1994.

Although selegiline is reported as being effective in treating the foregoing conditions, neither the precise number or nature of its mechanism or mechanisms of action are known. However, there is evidence that selegiline provides neuroprotection or neuronal rescue, possibly by reducing oxidative neuronal damage, increasing the amount of the enzyme superoxide dismutase, and/or reducing dopamine catabolism. For example, PCT Published Application WO 92/17169 reports that selegiline acts by directly maintaining, preventing loss of, and/or assisting in, the nerve function of animals.

Selegiline is disclosed as being useful when administered to a subject through a wide variety of routes of administration and dosage forms. For example U.S. Pat. No. 4,812,481 (Degussa AG) discloses the use of concomitant selegiline-amantadine in oral, peroral, enteral, pulmonary, rectal, nasal, vaginal, lingual, intravenous, intraarterial, intracardial, intramuscular, intraperitoneal, intracutaneous, and subcutaneous formulations. U.S. Pat. No. 5,192,550 (Alza Corporation) describes a dosage form comprising an outer wall impermeable to selegiline but permeable to external fluids. This dosage form may have applicability for the oral, sublingual or buccal administration of selegiline. Similarly, U.S. Pat. No. 5,387,615 discloses a variety of selegiline compositions, including tablets, pills, capsules, powders, aerosols, suppositories, skin patches, parenterals, and oral liquids, including oil-aqueous suspensions, solutions, and emulsions. Also disclosed are selegiline-containing sustained release (long acting) formulations and devices.

The present invention is directed to the novel, S(+) enantiomeric form of desmethylselegiline. This isomer has striking and wholly unexpected pharmacological effects and, accordingly, is surprisingly and unexpectedly useful in treating selegiline-responsive diseases and conditions. Assay results suggest that, in at least some respects, the S(+) enantiomer is considerably more effective than either selegiline or the R(-) enantiomer of desmethylselegiline. For example, results suggest that the S(+) enantiomer may be 4 5 times more effective than these other agents at inhibiting dopamine re-uptake by neurons and, in certain cell culture models, it has a greater neuroprotective effect than either R(-)desmethylselegiline or selegiline. Thus, the S (+) isomer is the form of choice in the treatment of conditions which require enhanced synaptic dopamine activity or neuronal protection/rescue. Such conditions include Parkinson's disease; Alzheimer's disease and attention deficit hyperactivity disorder (ADHD); dementia; depression; schizophrenia; and dysautonomia.

SUMMARY OF THE INVENTION

The present invention provides in part:

(a) a composition comprising the S(+) enantiomer of desmethylselegiline, a compound of the formula:

##STR00004## including the S(+) enantiomer in substantially isomerically pure form;

(b) a pharmaceutical composition comprising the S(+) enantiomer of desmethylselegiline, wherein one or more unit doses of said composition, administered on a periodic basis, are effective to treat a selegiline-responsive disease or condition in a animal to whom said unit dose or unit doses are administered;

(c) in a method for obtaining a selegiline-like therapeutic effect in a subject suffering from a selegiline-responsive disease or condition, the improvement which comprises:

administering to said subject the S(+) enantiomer of desmethylselegiline in a dosage regimen sufficient to produce said selegiline-like therapeutic effect.

(d) a method of treating a condition in a mammal produced by neuronal degeneration, neuronal trauma or by a hypodopaminergic condition which comprises administering to said mammal the S(+) enantiomer of desmethylselegiline or a pharmaceutically acceptable acid addition salt thereof, at a daily dose, administered in a single or multiple dosage regimen, of at least about 0.015 mg, calculated on the basis of the free secondary amine, per kg of the mammal's body weight;

(e) a transdermal delivery composition for use in treating a condition in a mammal produced by neuronal degeneration, neuronal trauma or due to a hypodopaminergic condition which comprises a layered composite containing in at least one layer an amount of the S(+) enantiomer of desmethylselegiline, or a pharmaceutically acceptable acid addition salt thereof, sufficient to supply a daily transdermal dose of at least about 0.015 mg of the free secondary amine, per kg of the mammal's body weight; and

(f) a method of treating a condition in a mammal produced by immune system dysfunction, which comprises administering to the mammal the S(+) enantiomer of desmethylselegiline, or a pharmaceutically acceptable acid addition salt thereof, at a daily dose, administered in a single or multiple dosage regimen, of at least about 0.015 mg, calculated on the basis of the free secondary amine, per kg of the mammal's body weight.

The present invention is based upon the discovery that both desmethylselegiline ("DMS" or "R(-)DMS") and its enantiomer (ent-desmethylselegiline, abbreviated as "ent-DMS" or "S(+)DMS") are useful in providing selegiline-like effects in subjects, notwithstanding dramatically reduced MAO-B inhibitory activity and an apparent lack of enhanced selectivity for MAO-B compared to selegiline. It has been discovered that desmethylselegiline, ent-desmethylselegiline and their isomeric mixtures provide a more advantageous way of obtaining selegiline-like therapeutic effects in selegiline-responsive diseases or conditions. This is particularly true for diseases or conditions characterized by neuronal degeneration, neuronal trauma or which are hypodopaminergic in nature, i.e. diseases or conditions characterized by reduced dopamine release and formation.

Thus, the present invention is directed to compositions comprising the S(+) enantiomer of desmethylselegiline either alone or together with the R(-) enanatiomer. In preferred embodiments, the S(+) enantiomer is present at a greater concentration than the concentration of the R(-) enantiomer or, alternatively, in substantially isomerically pure form. S(+) and R(-) forms of desmethylselegiline can be conveniently prepared by methods known in the art, as described below in Example 1. The characteristics of a preparation of purified S(+) enantiomer have been determined and are described in Example 3. Its chemical structure is as follows:

##STR00005##

The S(+) enantiomer, S(+)DMS, is used as an active ingredient in novel pharmaceutical compositions. In this regard, a quantity of the isomer is employed such that one or more unit doses of the composition is effective in the treatment of one or more selegiline-responsive diseases or conditions in a subject administered the composition on a periodic basis. If desired; the R(-) enantiomer may be included. Compositions may be designed so that they are suitable for oral, topical, transdermal, sublingual, buccal, parenteral or other conventional routes of administration. So formulated and administered, S(+)DMS compositions are useful for effecting an increase in dopaminergic activity, neuronal rescue/protection and can be administered in a manner so as to improve immune system function in a subject or to treat hypodopaminergic related diseases.

In addition, the present invention provides for an improved method for obtaining a selegiline-like therapeutic effect in a subject suffering from a selegiline-responsive disease or condition, which comprises administering to the subject the S(+) enantiomer of desmethylselegiline in an amount sufficient to produce the selegiline-like therapeutic effect. The S(+)DMS may be present in substantially isomerically pure form, a form preferred for the treatment of ADHD, or it may be present together with R(-)DMS.

As used herein the term "selegiline-responsive disease or condition" refers to any of the various diseases or conditions in mammals, including humans, for which selegiline is disclosed in the prior art as being useful. In particular, a "selegiline-responsive disease or condition" refers to the various diseases and conditions described above, e.g., Alzheimer's disease, cognitive dysfunction, neuronal rescue or protection, and the like. The term also refers to the use of selegiline as an appetite suppressant. Similarly, the term "selegiline-like therapeutic effect" refers to one or more of the salutary effects reported as being exerted by selegiline in subjects being treated for a selegiline-responsive disease or condition.

The selegiline-responsive diseases or conditions related to neuronal degeneration or trauma which respond to the present methods include Parkinson's disease, Alzheimer's disease, depression, glaucoma, macular degeneration, ischemia, diabetic neuropathy, attention deficit disorder, post polio syndrome, multiple sclerosis, impotence, narcolepsy, chronic fatigue syndrome, alopecia, senile dementia, hypoxia, cognitive dysfunction, negative symptomatology of schizophrenia, amyotrophic lateral sclerosis, Tourette's syndrome, tardive dyskinesia, and toxic neurodegeneration.

In preferred embodiments, the invention is directed to a method of treating a mammal for a hypodopaminergic condition or neuronal trauma/neuronal degeneration by administering the S(+) enantiomer of desmethylselegiline, or a pharmaceutically acceptable acid addition salt of this enantiomer, at a daily dose of at least about 0.015 mg per kg body weight. The dosage is based upon the weight of the free secondary amine and may be administered in either a single or multiple dosage regimen.

The present invention-also encompasses the restoration or improvement of immune system function by S(+)DMS. Again, the S(+) enantiomer may be administered either as a substantially pure isomer or in combination with R(-)DMS. The conditions or diseases treatable include age-dependent immune system dysfunction, AIDS, immunological loss due to cancer chemotherapy and infectious diseases. In a preferred embodiment, the invention is directed to a method of treating a condition in a mammal produced by immune system dysfunction, by administering the S(+) enantiomer of desmethyl-selegiline, or a pharmaceutically acceptable acid addition salt thereof, at a daily dose of at least about 0.015 mg, calculated on the basis of the free secondary amine, per kg of the mammal's body weight.

Depending upon the particular route employed, desmethylselegiline is administered in the form of a free base or as a physiologically acceptable non-toxic acid addition salt. Acid addition salts include those derived from organic and inorganic acids such as, Without limitation, hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid, methanesulphonic acid, acetic acid, tartaric acid, lactic acid, succinic acid, citric acid, malic acid, maleic acid, sorbic acid, aconitic acid, salicylic acid, phthalic acid, embonic acid, enanthic acid, and the like. The use of salts, especially the hydrochloride, is particularly desirable when the route of administration employs aqueous solutions, as for example parenteral administration. Use of delivered S(+)-desmethylselegiline, in the form of the free base is especially useful for transdermal administration. Reference herein to the administration of DMS or ent-DMS or to mixtures thereof encompasses both the free base and acid addition salt forms.

The optimal daily dose of S(+)-desmethylselegiline useful for the purposes of the present invention is determined by methods known in the art, e.g., based on the severity of the disease or condition being treated, the condition of the subject to whom treatment is being given, the desired degree of therapeutic response, and the concomitant therapies being administered to the patient or animal. Ordinarily, however, the attending physician or veterinarian will administer an initial dose of at least about 0.015 mg/kg, calculated on the basis of the free secondary amine, with progressively higher doses being employed depending upon the route of administration and the subsequent response to the therapy. Typically the daily dose will be about 0.10 mg/kg and may extend to about 1.0 mg/kg of the patient's body weight (all such doses again being calculated on the basis of the free secondary amine). These guidelines further require that the actual dose be carefully titrated by the attending physician or veterinarian depending on the age, weight, clinical condition, and observed response of the individual patient or animal.

The daily dose can be administered in a single or multiple dosage regimen. Oral dosage forms will most typically be used and are preferred but other dosage forms may also be employed and may permit, for example, a continuous release of relatively small amounts of the active ingredient from a single dosage unit, such as a transdermal patch, over the course of one or more days. This is particularly desirable in the treatment of chronic conditions such as Parkinson's disease, Alzheimer's disease, and depression. Alternatively, it may be desirable in conditions such as ischemia or neural damage to administer one or more discrete doses by a more direct systemic route such as intravenously or by inhalation. In still other instances such as glaucoma and macular degeneration, localized administration, such as via the intraocular route, can be indicated.

Pharmaceutical compositions containing S(+)-desmethylselegiline can be prepared according to conventional techniques. For example, preparations for parenteral routes of administration of S(+)-desmethylselegiline, e.g., intramuscular, intravenous and intraarterial routes, can employ sterile isotonic saline solutions. Sterile isotonic buffered solutions can also be employed for intraocular administration.

Transdermal dosage unit forms of S(+)-desmethylselegiline can be prepared utilizing a variety of previously described techniques (see e.g., U.S. Pat. Nos. 4,861,800; 4,868,218; 5,128,145; 5,190,763; and 5,242,950; and EP-A 404807, EP-A 509761, and EP-A 593807). For example, a monolithic patch structure can be utilized in which S(+)-desmethylselegiline is directly incorporated into the adhesive: and this mixture is cast onto a backing sheet. Alternatively S(+)-desmethylselegiline, can be incorporated as an acid addition salt into a multilayer patch which effects a conversion of the salt to the free base, as described for example in EP-A 593807. In a preferred embodiment, the present invention is directed to a transdermal delivery composition for use in treating a condition in a mammal produced by neuronal degeneration or neuronal trauma and for treating hypodopaminergic diseases.

Subjects treatable by the present preparations and methods include both human and non-human subjects for which selegiline-like therapeutic effects are known to be useful. Accordingly, the compositions and methods above provide especially useful therapies for mammals, especially domesticated mammals. Thus, the present methods and compositions are used in treating selegiline-responsive diseases or conditions in canine and feline species.

Successful use of the compositions and methods above requires employment of an effective amount of S(+)-desmethylselegiline. Although both R(-)desmethylselegiline and S(+)-desmethylselegiline are dramatically less potent than selegiline as inhibitors of MAO, employment of these agents, or a mixture of these agents, does not require a commensurately increased dosage to obtain a selegiline-like therapeutic response. Surprisingly, dosages necessary to attain a selegiline-like therapeutic effect appear to be on the same order as the known doses of selegiline. Accordingly, because both desmethylselegiline and ent-desmethylselegiline exhibit a much lower inhibition of MAO-A at such dosages, desmethylselegiline and ent-desmethylselegiline provide a substantially wider margin of safety with respect to MAO-A associated toxicity compared to selegiline. In particular, the risk of the adverse effects of MAO-A inhibition, e.g., hypertensive crisis, are minimized due to the reduced potency for MAO-A inhibition.

As described above and notwithstanding its demonstrably inferior inhibitory properties with respect to MAO-B inhibition, S(+)-desmethylselegiline appears to be at least as effective as selegiline in treating certain selegiline-responsive conditions, e.g., conditions resulting from reduced dopamine release and formation, neuronal degeneration or neuronal trauma. Although the oral route of administration will generally be most convenient, drug may be administered by the parenteral, topical, transdermal, intraocular, buccal, sublingual, intranasal, inhalation, vaginal, rectal or other routes as well.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1: HPLC Chromatogram of Purified R(-)DMS (Microsorb MV Cyano Column). The purity of a preparation of R(-)DMS was determined by HPLC on a Microsorb MV Cyano column and results are shown in FIG. 1. The column had dimensions of 4.6 mm.times.15 cm and was developed at a flow rate of 1.0 ml/min using a mobile phase containing 90% 0.01 M H.sub.3PO.sub.4(pH 3.5) and 10% acetonitrile. The column was run at a temperature of 40.degree. C. and effluent was monitored at a wavelength of 215 nm. The chromatogram shows one major peak appearing at a time of 6.08 minutes and having 99.5% of the total light-absorbing material eluted from the column. No other peak had greater than 0.24%.

FIG. 2: HPLC Elution Profile of R(-)DMS (Zorbax Mac-Mod C18 Column). The same preparation that was analyzed in the experiments discussed in FIG. 1 was also analyzed for purity by HPLC on a Zorbax Mac-Mod SB-C18 column (4.6 mm.times.75 mm). Effluent was monitored at 215 nm and results can be seen in FIG. 2. Greater than 99.6% of the light-absorbing material appeared in the single large peak eluting at a time of between 2 and 3 minutes.

FIG. 3: Mass Spectrum of R(-)DMS. A mass spectrum was obtained for purified R(-)DMS and results are shown in FIG. 3. The spectrum is consistent with a molecule having a molecular weight of 209.72 and a molecular formula of C.sub.12H.sub.15N.HCl.

FIG. 4: Infrared Spectrum (KBr) of Purified R(-)DMS. Infrared spectroscopy was performed on a preparation of R(-)DMS and results are shown in FIG. 4. The solvent used was CDCl.sub.3.

FIG. 5: NMR Spectrum of Purified R(-)DMS. A preparation Purified R(-)DMS was dissolved in CDCl.sub.3 and .sup.1H NMR spectroscopy was performed at 300 MHZ. Results are shown in FIG. 5.

FIG. 6: HPLC Chromatogram of S(+)DMS. The purity of a preparation of S(+)DMS was examined by reverse phase HPLC on a 4.6 mm.times.75 mm Zorbax Mac-Mod SB-C18 column. The elution profile, monitored at 215 nm, is shown in FIG. 6. One major peak appears in the profile at a time of about 3 minutes and contains greater than 99% of the total light-absorbing material that eluted from the column.

FIG. 7: Mass Spectrum of Purified S(+)DMS. Mass spectroscopy was performed on the same preparation examined in FIG. 6. The spectrum is shown in FIG. 7 and is consistent with the structure of S(+)DMS.

FIG. 8: Infrared Spectrum (KBr) of Purified S(+)DMS. The preparation of S(+)DMS discussed in connection with FIGS. 6 and 7 was examined by infrared spectroscopy and results are shown in FIG. 8.

FIG. 9: Effect of Selegiline on Neuron Survival. Mesencephalic cultures were prepared from embryonic 14 day rats. Cultures were used at about 1.5 million cells per plate and were maintained either in growth medium alone (control cultures) or in growth medium supplemented with selegiline. On day 1, 8 and 15, cells were immunostained for the presence of tyrosine hydroxylase ("TH"). Striped bars represent results obtained for cultures maintained in the presence of 50 .mu.M selegiline and open bars represent results for control cultures. In all cases, results are expressed as a percentage of TH positive cells present in control cultures on day 1. The abbreviation "DIV" refers to "days in vitro." Asterisks or stars above bars both in FIG. 9 and the figures discussed below indicates a result that differs from controls in an amount that is statistically significant, i.e. P<0.05.

FIG. 10: [.sup.3H]-Dopamine Uptake in Mesencephalic Cells. Cells, cultured as described above for FIG. 9, were tested for their uptake of labeled dopamine and results are shown in FIG. 10. Striped bars represent uptake in cells maintained in the presence of 50 .mu.M selegiline and open bars represent uptake in control cultures.

FIG. 11: Effect of Selegiline on Glutamate Receptor Dependent Neuronal Cell Death. Rat embryonic mesencephalic cells were cultured as described above. After allowing cultures to stabilize, the culture medium was changed daily for a period of 4 days to induce glutamate receptor-dependent cell death. Depending on the culture, medium contained either 0.5, 5.0 or 50 .mu.M selegiline. After the final medium change cultured cells were immunostained for the presence of tyrosine hydroxylase. From left to right, bars represent results for controls, 0.5, 5.0 and 50 .mu.M selegiline.

FIG. 12: Effect of Selegiline on Dopamine Uptake in Neuronal Cultures. Rat mesencephalic cells were cultured and medium was changed on a daily basis as discussed for FIG. 11. Uptake of tritiated dopamine by cells was measured and results are shown in the figure. From left to right, bars are in the same order as for FIG. 11.

FIG. 13: Effect of R(-)Desmethylselegiline on Glutamate Receptor Dependent Neuronal Cell Death. Rat embryonic mesencephalic cultures were prepared as described above except that R(-)DMS was used instead of selegiline. On day 9, the number of TH positive cells in cultures was determined. Results are expressed as a percentage of control. From left to right, bars show results for controls, 0.5, 5 and 50 .mu.M R(-)DMS.

FIG. 14: Effect of R(-)Desmethylselegiline on Dopamine Uptake in Neuronal Cultures. Cell cultures were prepared as described above for FIG. 13 and then tested for uptake of tritiated dopamine. Results for controls and for cells maintained in the presence of 0.5 .mu.M, 5 .mu.M and 50 .mu.M desmethylselegiline are shown from left to right in the figure.

FIG. 15: Comparison of Dopamine Uptake in Mesencephalic Cells Incubated in the Presence of Different Monoamine Oxidase Inhibitors. Rat embryonic mesencephalic cells were prepared as described for FIGS. 11 14 and incubated in the presence of a variety of monoamine oxidase inhibitors. The inhibitors examined were selegiline; R(-) desmethylselegiline; pargyline; and clorgyline, all at concentrations of 0.5, 5 and 50 .mu.M. In addition, cells were incubated in the presence of the glutamate receptor blocker MK-801 at a concentration of 10 .mu.M. Cultures were tested for uptake of tritiated dopamine.

FIG. 16: Relative Effectiveness of R(-) and S(+)DMS in Maintaining [.sup.3H]-Dopamine Uptake by Cultured Mesencephalic Cells (NMDA Model). Preparations of R(-) and S(+)DMS were assayed for their effect on [.sup.3H]-dopamine uptake by cultured rat mesencephalic cells exposed to the toxin N-methyl-D-aspartate (NMDA). Results were expressed as a percentage of the uptake seen in control cultures not exposed to NMDA and are shown in FIG. 16. From the left, the bars represent: cells incubated with medium alone; medium+5 .mu.M deprenyl; medium+0.5 .mu.M R(-)DMS; medium+5 .mu.M R(-)DMS; medium+50 .mu.M R(-)DMS; medium+0.5 .mu.M S(+)DMS; medium+5 .mu.M S(+)DMS; and medium+50 .mu.M S(+)DMS. All of the cell cultures shown in the figure were exposed to 100 .mu.M NMDA. Statistical significance was determined by ANOVA followed by Dunnett's test. One star above a bar indicates a percentage uptake that differs significantly from control uptake at the 0.05 confidence level. Two stars indicate a result that differs at the 0.01 confidence level.

FIG. 17: Relative Effectiveness of R(-) and S(+)DMS on Survival of Cultured Mesencephalic Cells (NMDA Model). Rat mesencephalic cell cultures were exposed to 100 .mu.M NMDA and incubated as described above in connection with FIG. 16. The effect of DMS enantiomers on the survival TH positive cells is shown in FIG. 17. The bars are in the same order as for FIG. 16 and results ate expressed as a percentage of control. One star indicates p<0.05 and two stars indicates p<0.01 when results are compared to those obtained for cells exposed to NMDA and then incubated in unsupplemented medium.

FIG. 18: Inhibition of Neuronal Dopamine Re-Uptake by Deprenyl and the Two Enantiomers of Desmethylselegiline. An in vitro nerve terminal preparation (synaptosome preparation) was prepared using fresh rat neostriatal-tissue. This was examined for its ability to take up tritiated dopamine in buffer alone or in buffer supplemented with various concentrations of selegiline, R(-)desmethylselegiline or S(+)desmethylselegiline. Uptake in the presence of each MAO inhibitor, expressed as a percent inhibition vs. log concentration of inhibitor is shown in FIG. 18. As indicated, the plot was used to determine the IC.sub.50 for each test agent.

FIG. 19: Determination of IC.sub.50 Values for Inhibition of Dopamine Re-Uptake. The experiment of FIG. 18 was repeated in a concentration range designed to more accurately provide an IC.sub.50 value and results are shown in FIG. 19. Using the log C vs. probit graphs, as shown in the figure, the IC.sub.50 for S(+)DMS was determined to be about 11 .mu.M; for selegiline, about 46 .mu.M; and for R(-)DMS about 54 .mu.M.

FIG. 20: In Vivo MAO-B Inhibition in Guinea Pig Hippocampus. Various doses of selegiline, R(-)desmethylselegiline, and S(+)desmethylselegiline were administered daily into guinea pigs for a period of 5 days. Animals were then sacrificed and the MAO-B activity in the hippocampus portion of the brain was determined. Results were expressed as a percent inhibition relative to hippocampus MAO-B activity in control animals and are shown in FIG. 20. The plots were used to estimate the ID.sub.50 dosage for each agent. The ID.sub.50 for selegiline was about 0.008 mg/kg; and for R(-)DMS, it was about 0.2 mg/kg; and for S(+)DMS, it was about 0.5 mg/kg.

DETAILED DESCRIPTION OF THE INVENTION

The surprising utility of S(+)desmethylselegiline and desmethylselegiline in treating certain selegiline-responsive diseases or conditions is attributable in part to their powerful action in preventing loss of dopaminergic neurons by promoting repair and recovery. Hence, at doses at which little or no MAO-B inhibition is generally observed, a reversal in neuronal damage and/or death can be observed. Because S(+)-desmethylselegiline is a more potent inhibitor of dopamine uptake and also can prevent loss and facilitate recovery of nerve cell function, it is of value in a wide variety of hypodopaminergic, neurodegenerative and neuromuscular diseases. In this regard, S(+)DMS is substantially more potent than R(-)desmethylselegiline, selegiline in certain pharmacological effects, as described more empirically in the examples below.

EXAMPLES

Example 1

Preparation of Desmethylselegiline and Ent-desmethylselegiline

A. Desmethylselegiline

Desmethylselegiline (designated below as "R(-)DMS") is prepared by methods known in the art. For example, desmethylselegiline is a known chemical intermediate for the preparation of selegiline as described in U.S. Pat. No. 4,925,878. Desmethylselegiline can be prepared by treating a solution of R(-)-2-aminophenylpropane (levoamphetamine).

##STR00006## in an inert organic solvent such as toluene with an equimolar amount of a reactive propargyl halide such as propargyl bromide, Br--CH.sub.2--C.ident.CH, at slightly elevated temperatures (70.degree. 90.degree. C.). Optionally the reaction can be conducted in the presence of an acid acceptor such as potassium carbonate. The reaction mixture is then extracted with aqueous acid, for example 5% hydrochloric acid, and the extracts are rendered alkaline. The nonaqueous layer which forms is separated, for example by extraction with benzene, dried, and distilled under reduced pressure.

Alternatively the propargylation can be conducted in a two-phase system of a water-immiscible solvent and aqueous alkali, utilizing a salt of R(+)-2-aminophenylpropane with a weak acid such as the tartrate, analogously to the preparation of selegiline as described in U.S. Pat. No. 4,564,706.

B. Ent-Desmethylselegiline

Ent-desmethylselegiline (designated below as "S(+)DMS") is conveniently prepared from the enantiomeric S(+)-2-aminophenylpropane (dextroamphetamine), i.e.,

##STR00007## following the procedures set forth above for desmethylselegiline.

C. Mixtures of Enantiomers

Mixtures of enantiomeric forms of desmethylselegiline, including racemic desmethylselegiline, are conveniently prepared from enantiomeric mixtures, including racemic mixtures of the above aminophenylpropane stating material.

D. Conversion Into Acid Addition Salts

N-(prop-2-ynyl).sub.2-aminophenylpropane in either optically active or racemic form can be converted to a physiologically acceptable non-toxic acid addition salt by conventional techniques such as treatment with a mineral acid. For example, hydrogen chloride in isopropanol is employed in the preparation of desmethylselegiline hydrochloride: Either the free base or salt can be further purified, again by conventional techniques such as recrystallization or chromatography.

Example 2

Characteristics of Substantially Pure R(-)DMS

A preparation of substantially pure R(-)DMS has the appearance of a white crystalline solid with a melting point of 162 163.degree. C. and an optical rotation of [.alpha.].sub.D.sup.23.degree. C.=-15.2+/-2.0 when measured at a concentration of 1.0 M using water as solvent. R(-)DMS appeared to be 99.5% pure when analyzed by HPLC on a Microsorb MV Cyano column (see chromatogram in FIG. 1) and 99.6% pure when analyzed by HPLC on a Zorbax Mac-Mod SB-C18 column (see chromatogram in FIG. 2). No single impurity is present at a concentration greater than or equal to 0.5%. Heavy metals are present at a concentration of less than 10 ppm and amphetamine hydrochloride at a concentration of less than 0.03%. The last solvents used for dissolving the preparation, ethyl acetate and ethanol are both present at a concentration of less than 0.1%. A mass spectrum performed on the preparation (see FIG. 3) is consistent with a compound having a molecular weight of 209.72 and a formula of C.sub.12H.sub.15N.HCl. Infrared and NMR spectra are shown in FIGS. 4 and 5 respectively. These are also consistent with the known structure of R-(-)-DMS.

Example 3

Characteristics of Substantially Pure S(+)DMS

A preparation of substantially pure S(+)DMS has the appearance of a white powder with a melting point of approximately 160.04.degree. C. and a specific rotation of +15.1 degrees when measured at 22.degree. C. in water, at a concentration of 1.0 M. When examined by reverse phase HPLC on a Zorbax Mac-Mod SB-C18 column the preparation appears to be about 99.9% pure (FIG. 6). Amphetamine hydrochloride is present at a concentration of less than 0.13% (w/w). A mass spectrum is performed on the preparation and is consistent with a compound having a molecular weight of 209.72 and a molecular formula of C.sub.12H.sub.15N.HCl (see FIG. 7). Infrared spectroscopy is performed and also provides results consistent with the structure of S(+)DMS (see FIG. 8).

Example 4

Neuronal Survival as Measured Using Tyrosine Hydroxylase

The effect of desmethylselegiline on neuron survival can be correlated to tyrosine hydroxylase, the rate limiting enzyme in dopamine biosynthesis. Assays are performed by determining the number of tyrosine hydroxylase positive cells in cultured E-14 embryonic mesencephalic cells over a period of 7 to 14 days. Protection in this system has been seen with a variety of trophic factors including BDNF, GDNF, EGF, and .beta.-FGF.

A. Test Methods

Timed pregnant Sprague-Dawley rats are used to establish neuronal cultures from embryonic rat brain on the 14th day of gestation. Mesencephalon is dissected out without the membrane coverings and collected in Ca.sup.++ and Mg.sup.++ free balanced salt solution at 4.degree. C. Tissue fragments are dissociated in chemically defined medium by mild trituration with a small bore pasteur pipette. Cell suspension is plated in polyornithine-coated 35 mm Falcon plastic dishes (0.1 mg/ml, Sigma) at a density of 1.5.times.10.sup.6 cells/dish. Cultures are maintained at 37.degree. C. in an atmosphere of 10% CO.sub.2/90% air and 100% relative humidity, and fed twice weekly with chemically defined medium consisting of MEM/F12 (1:1, Gibco), glucose (33 mM), HEPES (15 mM), NaHCO.sub.3 (44.6 mM), transferrin (100 mg/ml), insulin (25 mg/ml), putrescine (60 nM), sodium selenite (30 mM), progesterone (20 nM), and glutamine (2 mM). Control cells receive no further additions. The medium used for other cells also included test substance, e.g. selegiline, at one or more concentrations.

Cultures are fixed in 4% paraformaldehyde in 0.1 M phosphate buffer (pH 7.4) for 30 minutes at room temperature, permeabilized with 0.2% Triton X-100 for 30 minutes and incubated with an antibody against tyrosine hydroxylase (1:1000; Eugene Tech) for 48 hours at 4.degree. C. in the presence of a blocking serum. They are then stained using a peroxidase-coupled avidin-biotin staining kit (Vectastain ABC kit; Vector Labs) with 3',3'-diaminobenzidine as a chromagen.

The number of dopaminergic neurons in cultures is determined by counting the cells positively immunostained with TH antibodies. 100 fields (0.5 mm.times.0.5 mm) in two transverse strips across the diameter of the dish, representing 2.5% of the total area, are counted using a Nikon inverted microscope at 200.times. magnification.

B. Results

Using the procedures described above, the following results were obtained:

TABLE-US-00002 TABLE 2 Effect of Selegiline and DMS on the Survival of TH Positive Cells Control Selegiline Desmethylselegiline Mean Mean Mean Conc. cells/cm.sup.2 cells/cm.sup.2 % cont. cells/cm.sup.2 % cont. 0.5 .mu.M 108.55 201.70 .+-. 25.01 185.81 246.00 .+-. 22.76 226.62 5 .mu.M -- 237.00 .+-. 12.59 218.33 357.95 .+-. 25.76 329.76 50 .mu.M -- 292.28 .+-. 17.41 269.25 391.60 .+-. 34.93 360.76

Example 5

Neuronal Survival as Measured Using Dopamine Uptake

In addition to determining the number of TH positive cells in culture (see Example 4) the protective effect of desmethylselegiline on neuronal cells also can be determined by directly measuring dopamine uptake. The amount of uptake by the cultured brain cells corresponds to axonal growth.

A. Test Methods

Cell cultures, established in the manner discussed above, are incubated with [.sup.3H]dopamine (0.5 mCi/ml; 37 Ci/mmol; New England Nuclear) for 15 minutes in the presence of ascorbic acid (0.2 mg/ml) in PBS (pH 7.3), supplemented with 0.9 mM CaCl.sub.2 and 0.5 mM MgCl.sub.2 at 37.degree. C. After two rinses and a 5 minute incubation with fresh buffer, [.sup.3H]dopamine accumulated within the cells is released by incubating the cultures with 95% ethanol for 30 minutes at 37.degree. C. Preparations are then added to 10 ml Ecoscint (National Diagnostics) and counted in a scintillation spectrometer. Nonspecific uptake values are obtained by blocking dopaminergic neuronal uptake with 10 mM mazindol.

B. Results

Using the above procedure, the results shown in Table 3 were obtained.

TABLE-US-00003 TABLE 3 Effect of Selegiline and DMS on .sup.3H-Dopamine Uptake Cont. Selegiline Desmethylselegiline Conc. Mean Mean % Cont Mean % Cont 0.5 .mu.M 11982 14452 .+-. 212 120.6 24020 .+-. 800 200.4 5 .mu.M -- 16468 .+-. 576 137.5 34936 .+-. 2119 291.5 50 .mu.M -- 33018 .+-. 1317 275.5 56826 .+-. 2656 474.3

C. Conclusions from Examples 4 and 5

The results described in Examples 4 and 5 indicate that desmethylselegiline is substantially more potent than selegiline as a neuroprotective agent. This is true notwithstanding the fact that desmethylselegiline in much less potent than selegiline as an inhibitor of MAO-B.

Example 6

Neuroprotective Action of Desmethylselegiline Enantiomers in Cultured Dopamine-Containing Mesencephalic Neurons In Vitro

The survival of mesencephalic, dopamine-containing neuronal cultures of rat brain tissue was used in these experiments to examine neuroprotective properties of selegiline and R(-) desmethylselegiline. The number of TH positive neurons is directly proportional to the survival of dopaminergic neurons and .sup.3H-dopamine uptake is a measure of axonal growth in these neurons

A. Effect of Selegiline on the Survival of Dopaminergic Neurons.

Mesencephalic cultures prepared from embryonic day 14 rats were treated with 0.5, 5 or 50 .mu.M selegiline for 15 days, beginning on the day of plating. (For a more detailed discussion of the culturing of cells and other methods used in these experiments see Mytilineou et al., J. Neurochem. 61:1470 1478 (1993)). Survival and growth of dopamine neurons was evaluated by tyrosine hydroxylase (TH) immunocytochemistry and [.sup.3H]dopamine uptake and results are shown in FIGS. 9 and 10.

B. Effect of Selegiline on Glutamate Receptor Dependent Cell Death.

The neuroprotective effect of selegiline was also examined using an experimental paradigm that causes neuronal cell death that can be blocked by inhibition of glutamate receptors. In these experiments, cells were plated and allowed to stabilize for several days. The growth medium of the cells was then changed on a daily basis to induce cell death that can be prevented by blocking glutamate receptors, e.g. using MK-801. After 4 days of daily medium changes, cultures were stained for tyrosine hydroxylase and assayed for uptake of tritiated dopamine. The results shown in FIGS. 11 and 12 further support the conclusion that selegiline promotes the survival of dopaminergic neurons.

C. Effect of Desmethylselegiline on the Survival of Dopamine Neurons.

Using the glutamate receptor dependent model of neuron death, an even more potent protection of dopaminergic neurons was provided when desmethylselegiline was used in place of selegiline. Even at the lowest dose tested (0.5 .mu.M), desmethylselegiline caused a significant reduction in the loss of TH positive neurons (FIG. 13) and a significant increase in dopamine uptake (FIG. 14) relative to control cultures in which medium was used without supplementation with either selegiline or desmethylselegiline.

D. Comparison With Other MAO Inhibitors.

Using the glutamate receptor dependent model of neurotoxicity, the effects of selegiline and desmethylselegiline were compared with two other MAO inhibitors, pargyline and clorgyline (FIG. 15). In agreement with previous results, measurement of dopamine uptake indicated neuron protection by 50 .mu.M deprenyl and 5 and 50 .mu.M desmethylselegiline. Pargyline did not appear to offer any protection at the concentrations used, while clorgyline protected at 50 .mu.M. As expected, protection was also obtained by the NMDA receptor blocker MK-801 (10 .mu.M).

E. Effect of DMS Enantiomers on .sup.3H-Dopamine Uptake

The data summarized in Table 4 suggests that both (R-)DMS and S(+)DMS are effective as neuroprotectants in mesencephalic dopamine-containing neurons in culture.

TABLE-US-00004 TABLE 4 Effect of DMS Enantiomers on Dopamine Uptake .sup.3H-Dopamine uptake Treatment as a percentage .+-. SEM Control 100 .+-. 14.14% R(-)DMS (10 .mu.M) 140.82 .+-. 26.20% S(+)DMS (10 .mu.M) 234 .+-. 38.36%

These results were obtained using the medium change model of cell death. Compared to untreated control cells, ther