Evaluation of sex differences in the pharmacokinetics of ranitidine in humans

A bioequivalence study of two oral formulations of 300 mg ranitidine was carried out in 16 healthy volunteers (8 men and 8 women), and the pharmacokinetics in both sexes were compared. There was bioequivalence of both formulations. The terminal half-life of ranitidine was 7% shorter and the oral apparent clearance 10.5% higher in women (1.44 L/h/kg) than in men (1.29 L/h/kg), although this difference did not reach statistical significance. No differences were observed in maximum concentration (Cmax) or the time of its occurrence (tmax). Sex, age, and weight did not correlate significantly with oral clearance. These results suggest that there are no sex differences in the pharmacokinetics of ranitidine, or that any differences would not be of clinical relevance. It also should be emphasized that bioequivalence trials also can be used to study other pharmacokinetic or pharmacodynamic characteristics of drugs without damaging the main endpoint of the study.