title: Phenytoin--allopurinol interaction: Michaelis--Menten kinetic parameters of phenytoin with and without allopurinol in a child with Lesch--Nyhan syndrome.
abstract: We analyzed Michaelis--Menten pharmacokinetic parameters of phenytoin with and without the coadministration of allopurinol (150 and 200 mg/day) in a child with Lesch--Nyhan syndrome. The Vmax and Km were estimated from at least two different sets of serum concentration--dosage data of phenytoin. The Vmax values (mg/kg/day) were 16.1 without allopurinol, and 12.4 and 10.9 with allopurinol (150 and 200 mg/day), respectively, whereas those for Km remained relatively constant (3.9 to 4.9 microgram/ml). Our results suggest that allopurinol is a drug that inhibits the hepatic metabolism of phenytoin.
mesh_terms: D000293:Adolescent; D000493:Allopurinol / Q000494:pharmacology*; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D004347:Drug Interactions; D006801:Humans; D007700:Kinetics; D007926:Lesch-Nyhan Syndrome / Q000378:metabolism*; D008297:Male; D010672:Phenytoin / Q000378:metabolism*
chemical_list: D010672:Phenytoin; D000493:Allopurinol