Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Reexamination Certificate
1993-05-28
2001-09-11
Webman, Edward J. (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
C514S473000
Reexamination Certificate
active
06287598
ABSTRACT:
FIELD OF THE INVENTION
This invention pertains to a novel and to a nonobvious dosage form indicated for the management of epilepsies. The invention concerns also a composition comprising as antiepileptic drug and a carrier useful for manufacturing the dosage form and for dispensing the drug in an environment of use. The invention pertains further to a method for producing antiepileptic therapy in a patient in need of antiepileptic therapy.
BACKGROUND OF THE INVENTION
The term epilepsy is derived from a Greek word meaning a condition of being seized or overcome. The term epilepsy designates a group of central nervous system disorders having in common the occurrence of sudden and transitory episodes of abnormal behavioral symptoms of motor sensory, autonomic or psychic origin. Epilepsies have a definite onset and ending, and they usually are of short duration. Epilepsies are classified generally into two groups including generalized and partial, based on the type of seizures. Generalized seizures may involve a loss consciousness or convulsive movements, including tonic-clonic, myoclonic, tonic or clonic, and myoclonic astatic epilepsy. Partial seizures are divided into three subgroups including simple, complex, and secondarily generalized seizures.
Antiepileptic drugs are available for treating epilepsies. For example, valproic acid and its pharmaceutically acceptable salts are useful for treating epileptic phenomena. This drug is effective for its intended therapy; however, there are shortcomings associated with this drug. For instance, the antiepileptic drug valproic salt is extremely hygroscopic and liquefies very rapidly and it is sticky. The drug exhibits a short-half life that can lead to fluctuations in blood antiepileptic drug levels. These properties can interfere with the manufacture and release of the drug from a dosage form, and these shortcomings are serious drawbacks in the management of epilepsies.
Prior to this invention, the prior art administered an antiepileptic drug in a conventional dosage form like a tablet, or a capsule at repetitive dosing intervals. The prior art mode of therapy leads to a drug concentration in the blood during the dosing interval, and then a decrease in drug concentrations as a result of drug absorption, distribution, metabolism and elimination. The concentration difference in dosing intervals is related to the presence and to the absence of administered drug, which is a major disadvantage associated with conventional dosage forms. Conventional dosage forms and their mode of operation are discussed in Remington's
Pharmaceutical Sciences,
18th Edition, pages 1676 to 1686 (1990), Mack Publishing Co.;
The Pharmacological Basis of Therapeutics,
7th Edition, page 7, (1985) published by Macmillian Publishing Co.; Biopharmaceutics and Clinical Pharmacokinetics, 3rd Edition, pages 1 to 28, (1984), Published by Lea & Febiger, Philadelphia, Penn.; and in U.S. Pat. Nos. 3,598,122 and 3,598,123 both issued to Zaffaroni.
The above presentation dictates of the critical need for a dosage form that overcomes the shortcomings of conventional dosage forms, including tablets, capsules, elixirs and suspensions. These conventional dosage forms produce the peaks and valleys patterns discussed above, and they do not provide for dosage-regulated drug therapy over an extended period of time. The drug is dosed by the prior art twice or trice a day, which does not lead to controlled and sustained therapy. This prior art pattern of drug administration speaks of the need for a dosage form that can administer the drug in a rate-controlled pattern over an extended time to provide constant therapy and thereby eliminate the need for multiple dosing of the drug.
The prior art provided controlled-release dosage forms that can administer a drug continuously over time for controlled-rate therapy, as in, for example, in U.S. Pat. No. 4,327,725 issued to Cortese and Theeuwes and in U.S. Pat. Nos. 4,612,008; 4,765,989; and 4,783,337 issued to Wong, Barclay, Deters, and Theeuwes. The dosage forms disclosed in these patents provided a controlled rate of drug delivery over an extended time to provide constant drug therapy and thereby eliminate the need for multiple dosing of the drug. These dosage forms can deliver many drugs for their therapy, but there are certain drugs that are not readily manufactured and delivered from dosage forms. For example, sodium valproate because of its hygroscopic and tacky nature does not lean itself for providing a dosage form for controlled extended delivery since its properties hinder its manufacture into the dosage form and restrict its regulated delivery from such a dosage form.
It is immediately apparent, in the light of the above presentation, that an urgent need exists for a dosage form endowed with controlled-release delivery for administering valproic acid and its derivatives for antiepileptic valproic therapy. The need exists for this dosage form for delivering antiepileptic valproic acid in a controlled sustained dose in a therapeutic drug range and simultaneously provide extended therapy. It will be appreciated by those versed in the dispensing antiepileptic drug art, that such a dosage form that can administer an antiepileptic valproic drug in a controlled-rate dose over time, it would be a major advancement in the therapy of the epilepsies.
OBJECTS OF THE INVENTION
Accordingly, in view of the above presentation, it is an immediate object of this invention to provide a dosage form for delivering valproic acid and its derivatives that overcomes the shortcomings known to the prior art, and which dosage form can be manufactured by standard techniques.
Another object of the present invention is to provide a dosage form for the controlled delivery of valproic acid and its salts for maintaining an antiepileptic drug blood level in a therapeutic range over an extended time period.
Another object of the present invention is to provide a dosage form comprising means for stabilizing a hygroscopic antiepileptic drug contained in the dosage form.
Another object of the present invention is to provide a moisture-stable antiepileptic drug formulation and to the manufacture of the formulation into a dosage form.
Another object of the present invention is to provide a moisture-stable antiepileptic drug comprising a coating surrounding a hygroscopic antiepileptic drug particle that can be dispensed from a dosage form over an extended period of time.
Another object of the present invention is to provide a sustained-release dosage form that delivers an antiepileptic drug at a controlled-sustained rate for minimizing drug plasma fluctuations thereby providing antiepileptic drug in acute and chronic therapy.
Another object of the present invention is to provide a dosage form manufactured as an osmotic dosage form for the controlled delivery of antiepileptic valproic drug to a patient in need of antiepileptic valproic therapy.
Another object of the invention is to provide a method for treating a human being suffering from epilepsy, which method comprises administering to said human a dosage form containing an essentially moisture-stable antiepileptic drug.
Another object of this invention is to provide an improvement in a dosage form for administering a microencapsulated hygroscopic drug wherein the improvement comprises micro-encapsulating the hygroscopic drug with a water soluble polymer for substantially shielding the drug from a moisture environment.
Another object of the present invention is to provide a dosage form comprising microencapsulated drug granules that gradually release the drug resulting in a controlled and sustained release of the drug for improved plasma levels over a prolonged period of time up to thirty hours.
Another object of the present invention is to provide a dosage form for orally, buccally, or sublingually administering an antiepileptic drug surrounded with a polymer shield that imparts moisture-resistance to the antiepileptic drug.
Another object of the present invention is to provide a compressed composition comprisi
Ayer Atul Devatt
Pollock Brenda J.
Wong Patrick S.-L.
Yieh Richard L.-C.
ALZA Corporation
Miller D. Byron
Webb Samuel E.
Webman Edward J.
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