Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – N-c doai
Reexamination Certificate
2001-12-17
2003-07-29
Raymond, Richard L. (Department: 1624)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
N-c doai
C514S483000, C514S879000
Reexamination Certificate
active
06599935
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to novel derivatives of 2-phenyl-1,3-propanediol dicarbamate (felbamate), and the use of such derivatives as therapeutic agents. More particularly, compositions comprising the present felbamate derivatives can be administered for reducing the incidence and severity of epileptic seizures and for preventing and treating hypoxic damage resulting from an ischemic event.
BACKGROUND OF THE INVENTION
Felbamate (2-phenyl-1,3-propanediol dicarbamate) is a known pharmaceutical compound having been described in U.S. Pat. Nos. 2,884,444 and 4,868,327, the disclosures of which are expressly incorporated herein. Felbamate is a modulator of NMDA (N-methyl-D-aspartate) receptor function, and a glycine site antagonist but also has other reported mechanisms of actions.
Felbamate has also been reported to interact at the AMPA/kainate receptor, facilitate the function of the GABA receptor, and modulate Na.sup.+ channel conductance. Felbamate has also been demonstrated to decrease delayed neuronal cell death after kainic acid induced status epilepticus in animals. Glycine or d-serine were able to functionally reverse the anticonvulsant and ischemic protective effect of felbamate.
Felbamate has been proposed for use in treating various neurological disorders including the control of epileptic seizures. For example, U.S. Pat. No. 4,978,680 discloses the use of felbamate for the prevention and control of epileptic seizures; U.S. Pat. No. 5,082,861 relates to the use of felbamate for the prevention and control of epileptic seizures associated with complex partial seizures; and U.S. Pat. No. 5,292,772 relates to the use of felbamate for the prevention and control of epileptic seizures associated with Lennox-Gastaut syndrome. The disclosures of U.S. Pat. Nos. 4,978,680, 5,082,861 and 5,292,772 are expressly incorporated herein.
Felbamate has also been reported to have efficacy in reducing cellular damage resulting from vascular reperfusion (U.S. Pat. No. 5,462,966) and preventing and treating tissue damage resulting from an ischemic event (U.S. Pat. No. 5,055,489). For example, compositions comprising felbamate can be administered to control or prevent hypoxic damage resulting form stroke and other cerebral ischemic events. The disclosure of U.S. Pat. Nos. 5,462,966 and 5,055,489 are also expressly incorporated herein.
Felbamate was approved in July 1993 for the treatment of several forms of epilepsy. Felbamate demonstrated an excellent therapeutic index throughout preclinical and clinical trials with only relatively mild side effects observed and/or reported. In its first year of approval, between 100,000 and 125,000 patients were placed on felbamate therapy in the U.S. However, within the first year of felbamate's wide spread use, adverse reactions were reported, notably aplastic anemia and hepatotoxicity. (See Pennell et al.,
Neurology.
45, 456-460 (1995) and O'Neil et al.,
Neurology.
46, 1457-1459 (1996)). The severity and frequency of occurrence of these side effects prompted a recommendation by the FDA in August 1994 to withdraw patients from felbamate therapy, unless the benefit of seizure control outweighed the risk of the reported toxicities.
The present invention is directed to felbamate derivatives, and their metabolites, that exhibit therapeutic properties similar to felbamate, without the adverse reactions observed with felbamate administration. In accordance with the present invention these felbamate derivatives are used to treat neurological disorders and prevent and/or control tissue damage resulting from hypoxic conditions. More particularly, the present novel compounds are believed to be useful for treating epileptic seizures and for preventing or alleviating cellular damaged caused by myocardial or cerebral ischemic events.
The presently disclosed derivatives of felbamate have been shown to have activity as neuroprotectants and are believed to have biological activities similar to those of the parent felbamate compound. However, the present compounds have been modified to prevent the formation of metabolites that are believed to cause the adverse reactions associated with the use of felbamate. Accordingly, it is anticipated that the felbamate derivatives of the present invention can be substituted for felbamate for all the therapeutic uses that have been proposed for felbamate. In addition, many of the derivatives have enhanced activities allowing for the administration of lower therapeutically effective dosage forms.
SUMMARY OF THE INVENTION
The present invention is directed to novel compounds of the general formula:
wherein X is selected from the group consisting of
and R
1
, R
7
, R
8
, R
9
and R
10
are independently selected from the group consisting of H, halo, alkyl, haloalkyl, —NR
5
R
6
, hydroxy, and alkoxy, R
2
is halo, R
3
is hydroxy or —OCONH
2
, R
4
is hydroxy or carbonyl, and R
5
and R
6
are independently C
1
-C
4
alkyl. These novel compounds are derivatives of febamate; and in particular, the original felbamate structure has been modified to prevent the formation of metabolite 2-phenylpropenyl (atropaldehyde) upon administration to a warm blooded vertebrate. The formation of atropaldehyde is believed to be responsible for the adverse effects associated with the administration of felbamate. These felbamate derivatives exhibit similar activities to felbamate without the risk of the toxicities associated with felbamate administration. In accordance with the present invention compositions comprising a felbamate derivative are adminstered to a patient to provide neuroprotection in systemic and neurological disease and to treat tissue damage resulting from ischemic events. The compounds can be administered prophylactically, acutely, subacutely, or chronically via the intravenous, oral or rectal route.
DETAILED DESCRIPTION OF THE INVENTION
In describing and claiming the invention, the following terminology will be used in accordance with the definitions set forth below.
As used herein, the term “pharmaceutically acceptable carrier” encompasses any of the standard pharmaceutical carriers, such as a phosphate buffered saline solution, water and emulsions such as an oil/water or water/oil emulsion, and various types of wetting agents.
As used herein, “effective amount” means an amount sufficient to produce a selected effect. For example, an effective amount of a neuroprotective felbamate derivative is an amount of the active agent sufficient to significantly reduce the incidence and severity of epileptic seizures. An effective amount of a hypoxia ameliorating felbamate derivative is an amount of the active agent sufficient to prevent or significantly reduce cellular damage resulting from coronary artery occlusion/reperfusion or other hypoxia inducing event.
The general chemical terms used in the description of the compounds of the present invention have their usual meanings. For example, the term “alkyl” by itself or as part of another substituent means a straight or branched aliphatic chain having the stated number of carbon atoms.
The term “halo” includes bromo, chloro, fluoro, and iodo.
The term, “parenteral” means not through the alimentary canal but by some other route such as subcutaneous, intramuscular, intraspinal, or intravenous.
As used herein, the term “treating” includes alleviating the symptoms associated with a specific disorder or condition and/or preventing or eliminating said symptoms.
The following metabolic pathway (Scheme I) of felbamate (1) has been proposed that leads to the reactive metabolite, 3-carbamoyl-2-phenylpropionaldehyde (3).
3-Carbamoyl-2-phenylpropionaldehyde (3) is believed to be a reactive intermediate in the oxidation of 2-phenyl-1,3-propanediol monocarbamate (2) to the major human metabolite 3-carbamoyl-2-phenylpropionic acid (4). In addition, the aldehyde carbamate (3) was found to undergo spontaneous elimination to form the &agr;,&bgr; unsaturated aldehyde, 2-phenylpropenal (5), commonly known as atropaldehyde. Atropaldehyde has been proposed to play a ro
Patel Sudhaker B.
Raymond Richard L.
Schwegman Lundberg Woessner & Kluth P.A.
University of Virginia Patent Foundation
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