Absence of an inhibitory effect of omeprazole and nizatidine on phenytoin disposition, a marker of CYP2C activity

Abstract

The effects of omeprazole (40 mg orally per day) and nizatidine (300 mg orally per day) on the disposition of phenytoin (4.5 mg kg(-1) p.o. single dose) were studied in 18 healthy, young adult males. Total and unbound plasma concentrations of phenytoin were measured for 48 h after each dose of phenytoin. Neither treatment altered the disposition kinetics of phenytoin, the hydroxylation of which is mediated specifically by cytochromes P450 of the 2C subfamily.