The effect of cimetidine on the pharmacokinetics of single oral doses of alfuzosin.

Alfuzosin is a new alpha 1-adrenoceptor antagonist particularly effective in the symptomatic treatment of benign prostatic hypertrophy (BPH). The elimination of alfuzosin being almost entirely metabolic, the potential pharmacokinetic interaction with cimetidine (H2-receptor antagonist) was investigated in 10 healthy young subjects. Pharmacokinetics of alfuzosin were appraised as a 5 mg oral dose before, after one day and after 20 days of cimetidine (1 g/d) administration. An inhibition of the hepatic mixed function oxidase system by cimetidine was established by the oral antipyrine clearance test. Under these conditions, alfuzosin pharmacokinetics were only marginally affected by concomitant cimetidine administration. Surprisingly, a significantly shorter elimination half-life was found after 20 days on cimetidine (from 5.1 +/- 0.4 h to 4.4 +/- 0.5 h). This fact must be attributed to the large inter-individual variation in pharmacokinetic parameters reported for alfuzosin. Cmax and AUC increased up to 20% after cimetidine but without statistical significance. No side-effects on the association cimetidine-alfuzosin were reported. In conclusion, there is a lack of pharmacokinetic interaction on cimetidine-alfuzosin co-administration.