Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0014547 (focal epilepsy)
 1,627 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Despite the introduction of a host of new antiepileptic drugs (AEDs) over the last 20 years, the older agents, which are potent inducers of the cytochrome P450 (CYP450) system, remain the AEDs most commonly prescribed throughout the world. At the same time, data have gradually and continuously emerged regarding the possible adverse consequences of CYP450 induction, such that it is now appropriate to pose the question of whether the inducing drugs should still be considered first-line agents for the treatment of focal epilepsy. In this article we review the evidence suggesting that these drugs may have many detrimental metabolic effects, along with the data concerning their relative efficacy compared to the newer, noninducing AEDs. We conclude that longer and better-powered studies are needed to truly establish whether the newer AEDs are equivalent in efficacy to the older, inducing agents. Pending this, however, the extant data are sufficiently concerning to suggest that it may be prudent to start with noninducing AEDs unless there is a clear indication for one of the inducing drugs.
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PMID:Should enzyme-inducing antiepileptic drugs be considered first-line agents? 1970 33

Stiripentol is a structurally unique antiepileptic drug that has several possible mechanisms of action, including diverse effects on the gamma-aminobutyric acid (GABA)-A receptor and novel inhibition of lactate dehydrogenase. Because of its inhibition of several cytochrome P450 enzymes, it has extensive pharmacokinetic interactions, which often necessitates reduction in doses of certain co-therapies, particularly clobazam. Stiripentol also has a neuroprotective action, by reducing calcium-mediated neurotoxicity. Evidence of its efficacy is most robust for Dravet syndrome, where stiripentol added to clobazam and valproic acid reduces seizure frequency and severity in the majority of cases. Small case series have also suggested benefit for malignant migrating partial seizures in infancy, super-refractory status epilepticus, and intractable focal epilepsy, although larger prospective studies are needed in these disorders.
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PMID:Stiripentol in the Management of Epilepsy. 2843 33

Phenytoin (PHT) is an antiepileptic drug widely used in the treatment of focal epilepsy and status epilepticus, and effective in controlling focal seizures with and without tonic-clonic generalization and status epilepticus. The metabolization of PHT is carried out by two oxidative cytochrome P450 enzymes CYP2C9 and CYP2C19; 90% of this metabolization is done by CYP2C9 and the remaining 10% by CYP2C19. Genetic polymorphism of CYP2C9 may reduce the metabolism of PHT by 25-50% in patients with variants *2 and *3 compared to those with wild-type variant *1. The frequency distribution of CYP2C9 polymorphism alleles in patients with epilepsy around the world ranges from 4.5 to 13.6%, being less frequent in African-Americans and Asians. PHT has a narrow therapeutic range and a nonlinear pharmacokinetic profile; hence, its poor metabolization has significant clinical implications as it causes more frequent and more serious adverse effects requiring discontinuation of treatment, even if it had been effective. There is evidence that polymorphisms of CYP2C9 and the use of PHT are associated with an increase in the frequency of some side effects, such as cerebellar atrophy, gingival hypertrophy or acute cutaneous reactions. The presence of HLA-B*15:02 and CYP2C9 *2 or *3 in the same patient increases the risk of Stevens-Johnson syndrome and toxic epidermal necrolysis; hence, PHT should not be prescribed in these patients. In patients with CYP2C9 *1/*2 or *1/*3 alleles (intermediate metabolizers), the usual PHT maintenance dose (5-10 mg/kg/day) must be reduced by 25%, and in those with CYP2C9 *2/*2, *2/*3 or *3/*3 alleles (poor metabolizers), the dose must be reduced by 50%. It is controversial whether CYP2C9 genotyping should be done before starting PHT treatment. In this paper, we aim to review the influence of CYP2C9 polymorphism on the metabolization of PHT and the clinical implications of poor metabolization in the treatment of epilepsies.
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PMID:CYP2C9 polymorphisms in epilepsy: influence on phenytoin treatment. 2963 28