Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Reexamination Certificate
2003-01-27
2004-06-29
Henley, III, Raymond (Department: 1614)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
Reexamination Certificate
active
06756379
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to the use of non-sedating barbiturate compounds given in a manner and dosage effective to produce blood levels and brain levels of these drugs and/or their active metabolites sufficient to provide a neuroprotectant effect. In particular, the methods and formulations of the invention permit treatment of cerebral ischemia, head trauma and other acute neurologic injuries, and prevention of resulting neuronal damage.
Ischemia (stroke) is the third leading cause of death in the United States. When blood supply to the brain is reduced below a critical threshold, a cascade of biochemical events leads to irreversible damage to neurons and brain infarction. Research on treatment and prevention of ischemia is extensive but unfortunately it remains at a basic stage and no adequate therapies are yet in practice (10).
Barbiturates in high concentrations have been shown to be neuroprotective in cerebral ischemia in rodents and primates, to reduce the extent of ischemia brain infarction, and to prevent or lessen brain damage (1-4). One theory as to how barbiturates prevent neuronal injury in ischemia is that they inhibit the ischemia-induced uncontrolled release of neurotransmitters, which can attain high, neurotoxic concentrations that cause neuronal death (5).
The literature regarding the neuroprotective effects of anesthetic barbiturates is over two decades old, but the clinical use of barbiturates has been severely limited because of toxicity. The dosages and blood and brain levels necessary to confer neuroprotection are toxic and cause lethargy, stupor, and coma. Even higher doses that might be more effective are lethal (1-4, 6), making barbiturates unsuitable for treatment of ischemia (1). These toxic side effects establish a “functional ceiling” on dosage for barbiturates, and have discouraged further research into the use of anesthetic/sedative barbiturates to protect from ischemia.
Levitt et al., U.S. Pat. No. 4,628,056 describes non-sedating oxopyrimidine derivatives and their use as anticonvulsants, anti-anxiety and muscle relaxant agents. The literature does not suggest the use of such compounds as neuroprotectant agents. Indeed, even. in published studies about using sedative barbiturates for neuroprotection there is no reference to non-sedating barbiturate compounds. It is generally believed that the anticonvulsant and neuroprotective effects of barbiturates are linked to their sedative/hypnotic effects For example, Lightfoote et al. suggested that the protective effects of pentobarbital are due to the duration of the barbiturate-induced anesthesia (3). This viewpoint has been reinforced by biochemical studies at the cell receptor level that relate all these effects to action at the GABA receptor. Thus, the prior art teaches away from using sedative barbiturates for neuroprotection because of their toxicity, and also teaches away from using non-sedative barbiturates as neuroprotectants because they lack sedating or anesthetic properties.
SUMMARY OF THE INVENTION
In summary, the invention involves non-sedating barbiturates such as for example 1,3-dimethoxymethyl 5,5-diphenyl-barbituric acid (DMMDPB), 1-monomethoxymethyl 5,5-diphenylbarbituric acid (MMMDPB) an diphenyl-barbituric acid (DPB) and their precursors, derivatives and analogs, and their administration over a range of dosages that result in a range of blood levels and brain levels of these drugs and their metabolites making them useful as neuroprotectants. In particular, the invention is directed to the treatment of cerebral ischemia, head trauma and other acute neurologic injuries, using non-sedating barbiturates.
There are many circumstances where individuals at risk of cerebral ischemia are clearly identified in advance, for example: individuals undergoing cardiac surgery or carotid endarterectomy, and individuals with atrial fibrillation, transient ischemic attacks (TIAs), bacterial endocarditis, strokes, or subarachnoid hemorrhage due to a cerebral aneurysm. In such cases, a non-sedating barbiturate is used prophylactically in individuals at risk for ischemic damage. The drugs can also be used after an acute event. These compounds can be given in oral form as a tablet, capsule, liquid or via intravenous or other parental routes.
This invention succeeds where previous efforts to treat cerebral ischemic attack with barbiturates have failed. This invention solves a problem previously thought to be insoluble, that of toxic effects of neuroprotective dosages of barbiturates. The invention avoids the toxicity and sedative effects of barbiturates known in the prior art without loss of efficiency.
This invention satisfies a long-felt need for a non-toxic neuroprotectant, and is contrary to the teachings of the prior art regarding the inability of barbiturates to produce clinically meaningful neuroprotection. According to the invention, it is possible to separate the anticonvulsant and sedative effects of barbiturates, and neuroprotection correlates much better with the anticonvulsant rather than the sedative effect of barbiturates.
This invention differs from the prior art in the recognition of specific compounds, their modifications and dosages that are effective in neuroprotection but that were not previously recognized.
The present invention is a method for providing neuroprotection to a mammal, preferably a human. The method comprises administering to the mammal a non-sedating barbiturate in a dose effective to provide a neuroprotection effect. Non-sedating barbiturates for use in the invention include one or more selected from the group consisting of 1,3-dimethoxymethyl 5,5-diphenyl-barbituric acid (DMMDPB), 1-monomethoxymethyl 5,5-diphenylbarbituric acid (MMMDPB), and diphenyl barbituric acid. The precursor, derivatives and analogs of the foregoing compounds, as well as the salts of all the foregoing are also suitable for practicing the invention.
The effective neuroprotective dose of the non-sedative barbiturate preferably exceeds the coma-producing dose of a sedative barbiturate. Depending on the specific need of the mammal, the dose of the non-sedative barbiturate may exceed a dose that would be lethal with a sedative barbiturate. This unexpected and seemingly paradoxical effect of the present method is further reflected in the relative dosage levels that are possible with the methods of this invention.
Also, the neuroprotective dose of the non-sedative barbiturate exceeds the minimum anticonvulsant dosage of the barbiturate. In some embodiments of the present invention the effective dose of the non-sedative barbiturate is in the range of from about 2 times to about 5 times the anticonvulsant dosage. In yet other contexts where the need of the mammal requires, the effective dose of the non-sedative barbiturate is in the range of from about 5 times to about 10 times the anticonvulsant dosage of the non-sedative, or even higher so long as the dose is clinically acceptable.
Advantageously, the neuroprotective effect of the present methods can be used to mitigate the effect of cerebral ischemic. The non-sedating barbiturate can be administered orally, intravenously, transdermally, in combination with an adjuvant, or transpulmonarily by means of a particulate or aerosol inhalant. Moreover, within the scope of the invention, the non-sedating barbiturate can be administered preventively, prophylactically or therapeutically, at a clinically acceptable dose. The compound may be administered prophylactically before evident neuronal damage, or therapeutically after onset of neuronal damage. The neuroprotective effect diminishes, or protects the subject from, neuronal damage caused by head trauma or cerebral ischemia. The compound may be administered in conjunction with cardiac surgery or carotid endarterectomy. The mammalian subject may have or be at risk for atrial fibrillation, a transient ischemic attack (TIA), bacterial endocarditis, a stroke, head trauma, or subarachnoid hemorrhage.
Typically, to achieve neuroprotection the non-sedating barbiturate is administered in a
Levitt Barrie
Moros Daniel A.
Yacobi Avraham
Genieser Lars H.
Gollin Michael A.
Henley III Raymond
Taro Pharmaceutical Industries Ltd.
Venable LLP
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