Derivatives of (−)-venlafaxine and methods of...

Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Nitrogen containing other than solely as a nitrogen in an...

Reexamination Certificate

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C564S336000

Reexamination Certificate

active

06342533

ABSTRACT:

1. FIELD OF INVENTION
The invention relates to optically pure derivatives of (−)-venlafaxine, methods of their synthesis, compositions comprising them, and methods of their use.
2. BACKGROUND OF THE INVENTION
A number of nontricyclic antidepressants have recently been developed that diminish the cardiovascular and anticholinergic liability characteristic of tricyclic antidepressants. Some of these compounds are used as anti-obesity agents and have shown promise in the treatment of cerebral function disorders such as Parkinson's disease and senile dementia. See, e.g., WO 94/00047 and WO 94/00114. The nontricyclic compound venlafaxine, chemically named (±)-1-[2-(dimethylamino)-1 -(4-methoxyphenyl)ethyl]-cyclohexanol, is an antidepressant which has been studied extensively and which is described in, for example, U.S. Pat. No. 4,761,501 and Pant, J. T.
Drugs of the Future
13(9):839-840 (1988). Its hydrochloride salt is currently commercially available in the United States under the trade name Effexor®. Effexor®, which is a racemic mixture of the (+) and (−) enantiomers of venlafaxine, is indicated for the treatment of depression.
Although venlafaxine contains an asymmetric carbon atom and is sold as a racemate, it has been reported that its (−) enantiomer is a more potent inhibitor of norepinephrine synaptosomal uptake while its (+) enantiomer is more selective in inhibiting serotonin uptake. Howell, S. R. et al.
Xenobiotica
24(4):315-327 (1994). Furthermore, studies have shown that the ratio of the two isomers' metabolism varies not only among species, but between subjects as well. Klamerus, K. J. et al.
J. Clin. Pharmacol
. 32:716-724 (1992). In humans, venlafaxine is transformed by a saturable metabolic pathway into two minor metabolites, N-desmethylvenlafaxine and N,O-didesmethylvenlafaxine, and one major metabolite, O-desmethylvenlafaxine, as shown in Scheme I(a):
Klamerus, K. J. et al.
J. Clin. Pharmacol
. 32:716-724 (1992). All of these metabolites are racemic. In vitro studies suggest that O-desmethylvenlafaxine is a more potent inhibitor of norepinephrine and dopamine uptake than the parent compound racemic venlafaxine. Muth, E. A. et al.
Drug Develop. Res
. 23:191-199 (1991). O-desmethylvenlafaxine has also been reported to have a half-life (t½) of about 10 hours, which is approximately 2.5 times as long as that of venlafaxine. Klamerus, K. J. et al.
J. Clin. Pharmacol
. 32:716-724 (1992). Studies directed at understanding-the activity of O-desmethylvenlafaxine as compared to its parent have been hampered, however, by the metabolic difference between laboratory animals and man in their exposure to venlafaxine. Howell, S. R. et al.
Xenobiotica
24(4):315-327 (1994).
Despite the benefits of racemic venlafaxine, it has adverse effects including, but not limited to, sustained hypertension, headache, asthenia, sweating, nausea, constipation, somnolence, dry mouth, dizziness, insomnia, nervousness, anxiety, blurred or blurry vision, and abnormal ejaculation/orgasm or impotence in males.
Physicians' Desk Reference
pp. 3293-3302 (53
rd
ed., 1999); see also Sinclair, J. et al.
Rev. Contemp. Pharmacother
. 9:333-344 (1998). These adverse effects can significantly limit the dose level, frequency, and duration of drug therapy. It would thus be desirable to find a compound with the advantages of venlafaxine while avoiding its disadvantages.
3. SUMMARY OF THE INVENTION
This invention relates to novel pharmaceutical compositions comprising optically pure derivatives of (−)-venlafaxine such as (−)-O-desmethylvenlafaxine. The invention also relates to methods of preparing optically pure derivatives of (−)-venlafaxine with high purity and in high yield, and to methods of treating and preventing diseases and disorders which comprise the administration of one or more optically pure derivatives of (−)-venlafaxine to a human in need of such treatment or prevention.
Methods and compositions of the invention can be used to treat or prevent depression and affective disorders such as, but not limited to, attention deficit disorder and attention deficit disorder with hyperactivity. Methods and compositions of the invention are also useful in treating obesity and weight gain in a human. The invention also encompasses the treatment of cerebral function disorders including, but not limited to, senile dementia, Parkinson's disease, epilepsy, Alzheimer's disease, amnesia/amnestic syndrome, autism and schizophrenia; disorders ameliorated by inhibition of neuronal monamine reuptake; and pain, particularly chronic pain. The invention further encompasses the treatment or prevention of obsessive-compulsive disorder, substance abuse, pre-menstrual syndrome, anxiety, eating disorders and migraines. The invention finally encompasses the treatment or prevention of incontinence in humans.
The compounds and compositions of the invention possess potent activity for treating or preventing the above-described disorders while reducing or avoiding adverse effects including, but not limited to, sustained hypertension, headache, asthenia, sweating, nausea, constipation, somnolence, dry mouth, dizziness, insomnia, nervousness, anxiety, blurred or blurry vision, and abnormal ejaculation/orgasm or impotence in males. In particular, adverse effects associated with the administration of racemic venlafaxine are reduced or avoided by the use of optically pure derivatives of (−)-venlafaxine. Compositions of the invention can also exhibit long half lives as compared to racemic venlafaxine.
Although a variety of pharmaceutical salts, solvates, clatherates and/or hydrates (including anhydrous forms) of the active ingredients disclosed herein are suitable for use in the methods and compositions of the invention, the optically pure derivatives of (−)-venlafaxine are typically prepared as hydrochloride salts, and preferably as the monohydrates.
3.1. DEFINITIONS
As used herein, the terms “venlafaxine” and “(±)-venlafaxine” mean the racemic compound (±)-1-[2-(dimethylamino)-1-(4-methoxyphenyl)ethyl]cyclohexanol.
As used herein, the terms “venlafaxine derivative” and “derivative of venlafaxine” encompass, but are not limited to, human metabolites of racemic venlafaxine. In particular, the terms “venlafaxine derivative” and “derivative of venlafaxine” mean a compound selected from the group that includes, but is not limited to: (±)-N-desmethylvenlafaxine, chemically named (‥)-1 -[2-(methylamino)-1 -(4-methoxyphenyl)ethyl] cyclohexanol; (±)-N,N-didesmethylvenlafaxine, chemically named (±)-1 -[2-(amino)-1 -(4-methoxyphenyl)ethyl]cyclohexanol; (±)-O-desmethylvenlafaxine, chemically named (±)-1-[2-(dimethylamino)-1-(4-phenol)ethyl]cyclohexanol; (±)-N,O-didesmethylvenlafaxine, chemically named (±)-1 - [2-(methylamino)-1 -(4-phenol)ethyl]cyclohexanol; and (±)-O-desmethyl-N,N-didesmethylvenlafaxine, chemically named chemically named (±)-1-[2-(amino)-1-(4-phenol)ethyl]cyclohexanol.
As used herein, the terms “(−)-venlafaxine derivative” and “derivative of (−)-venlafaxine” encompass, but are not limited to, optically pure human metabolites of (−)-venlafaxine. In particular, the terms “(−)-venlafaxine derivative” and “derivative of (−)-venlafaxine” mean a compound selected from the group that includes, but is not limited to: optically pure (−)-N-desmethylvenlafaxine, chemically named (−)-1-[2-(methylamino)-1-(4-methoxyphenyl)ethyl]cyclohexanol; optically pure (−)-N,N-didesmethylvenlafaxine, chemically named (−)-1-[2-(amino)-1-(4-methoxyphenyl)ethyl]cyclohexanol; optically pure (−)-O-desmethylvenlafaxine, chemically named (−)-1-[2-(dimethylamino)-1-(4-phenol)ethyl]cyclohexanol; optically pure (−)-N,O-didesmethylvenlafaxine, chemically named (−)-1-[2-(methylamino)-1-(4-pheno

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