Epileptic disorders : international epilepsy journal with videotape
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Review
The ideal pharmacokinetic properties of an antiepileptic drug: how close does levetiracetam come?
The pharmacokinetic properties of a drug are the primary deter-minant of the extent and duration of drug action, and influence susceptibility to clinically important drug interactions. Most of the older-generation antiepileptic drugs (AEDs) are far from ideal in terms of pharmacokinetics and interaction potential. ⋯ One of the most recently developed of these drugs, levetiracetam, comes especially close to fulfilling the desirable pharmacokinetic characteristics for an AED: (1) it has a high oral bioavailability, which is unaffected by food; (2) it is not significantly bound to plasma proteins; (3) it is eliminated partly in unchanged form by the kidneys and partly by hydrolysis to an inactive metabolite, without involvement of oxidative and conjugative enzymes; (4) it has linear kinetics; and (5) it is not vulnerable to important drug interactions, nor does it cause clinically significant alterations in the kinetics of concomitantly administered drugs. Although its half-life is relatively short (6 to 8 hours), its duration of action is longer than anticipated from its pharmacokinetics in plasma, and a twice-daily dosing regimen is adequate to produce the desired response.
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The search for antiepileptic drugs (AEDs) using drug screens that test for the ability to suppress paroxysmal events has primarily resulted in the discovery of AEDs that inhibit neuronal excitability. While profoundly reducing expression of epileptic seizures, current pharmacologic treatments have not been able to completely control seizures in all patients, and can impair normal neuronal excitation underlying cognition. A new approach to drug screening, including the process of epileptogenesis, may yield new classes of drugs that not only suppress seizures but also specifically act to protect against the neurobiological changes that contribute to the development of epilepsy. ⋯ One new AED with potential antiepileptogenic properties is levetiracetam, which was discovered using non-conventional drug screens. It markedly suppresses kindling development at doses devoid of adverse effects, with persistent suppression of kindled seizures even after termination of treatment. Further design and implementation of antiepileptogenic drug screens are needed for the discovery of other novel disease-modifying agents.