URINARY 6-BETA-HYDROXYCORTISOL AND D-GLUCARIC ACID EXCRETION RATES ARE NOT AFFECTED BY LANSOPRAZOLE TREATMENT

Lansoprazole has been shown to induce cytochrome P450 1A (CYP1A) and C YP3A enzymes in human hepatocytes in vitro. In this study, urinary exc retion of 6 beta-hydroxycortisol (6 beta-OHF) and D-glucaric acid (D-G A) were used to investigate the potential enzyme-inducing property of lansoprazole in vivo. Twenty-four healthy female volunteers (aged 19 - 35 years), who were taking oral contraceptives containing 0.03 mg eth inylestradiol and 0.15 mg levonorgestrel, were randomized in a cross-o ver design for the treatment with either 60 mg lansoprazole or placebo once daily during 2 subsequent menstrual cycles. Urinary excretion ra tes of 6 beta-OHF and D-GA were measured at days 14 and 21 of the mens trual cycles. Median pretreatment urinary excretion of 6 beta-OHF (212 and 218 mu g/d, n = 24) and D-GA (20.1 and 32.7 mu mol/d) did not sig nificantly differ. Upon treatment median excretion of 6 beta-OHF was 2 55 and 241 mu g/d (n = 23), and that of D-GA was 25.5 and 33.8 mu mol/ d, respectively. Thus, the relatively high dose of 60 mg/d lansoprazol e failed to statistically significantly alter urinary excretion of 6 b eta-OHF and D-GA, indicating that therapeutic doses of lansoprazole mi ght not exhibit a phenobarbital-like induction in vivo.