Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mephenytoin (3-methyl-5-ethyl-5-phenylhydantoin) is metabolized to Nirvanol (5-ethyl-5-phenylhydantoin). Both compounds block the hind leg tonic extensor phase of the Maximal Electroshock Seizure (M.E.S.) Test in mice. The M.E.S. ED50 of mephenytoin is 42 mg/kh at 30 min and 35 mg/kg at 2 hr after ip administration. The M.E.S. ED50 for Nirvanol at 30 min and 2 hr was 23 and 30 mg/kg, respectively. Brain and plasma levels of mephenytoin and Nirvanol were determined by gas-liquid chromatography after ip administration of 40 mg of mephenytoin per kg. At 30 min the brain levels of mephenytoin and Nivanol were 19.2 and 8.1 mug/g, respectively. The brain levels of mephenytoin fell to 5.8 mug/g and those of Nirvanol rose to 18.2 mug/g at 2 hr. The total molar concentration of mephenytoin and Nirvanol, however, did not change more than 10% during the 2-hr period. Although the anticonvulsant activity of mephenytoin did not vary greatly during 2 hr after administration, the early activity is due in major part fo mephenytoin and the later activity to Nirvanol.
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PMID:The metabolism of 3-methyl-5-ethyl-5-phenylhydantoin (mephenytoin) to 5-ethyl-5-phenylhydantoin (Nirvanol) in mice in relation to anticonvulsant activity. 23 31

We investigated the conversion of mephenytoin to nirvanol in five patients with uncontrolled complex partial seizures. After a 50-mg single oral dose, mean peak mephenytoin level was 0.48 microgram/ml and nirvanol 0.37 microgram/ml. After 400 mg, peak mephenytoin level was 3.9 micrograms/ml and nirvanol 2.5 micrograms/ml. On 400 mg daily, mephenytoin reached a mean steady-state level of 1.5 micrograms/ml. Nirvanol mean steady-state level was 18 micrograms/ml. Mean plasma half-life was 17 hours for mephenytoin and 114 hours for nirvanol. Two patients had reduced seizures during mephenytoin therapy and one a transient increase during drug withdrawal. No toxicity was seen, but mephenytoin was not more effective than phenytoin.
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PMID:Disposition of mephenytoin and its metabolite, nirvanol, in epileptic patients. 643 15