Comparison of the bioavailability and pharmacokinetics of oral methylergometrine in men and women.

OBJECTIVE To assess and compare the pharmacokinetics and bioavailability of methylergometrine (ME) in men and non-pregnant women. DESIGN A cross-over design was used for an oral dose of 0.125 mg and an intravenous dose of 0.200 mg of ME in 6 men and 6 non-pregnant women (parallel-design in gender). RESULTS After intravenous administration, the pharmacokinetic profile of ME was described with a 2-compartment model. The distribution half-life (t1/2 alpha) in men was 0.19 +/- 0.27 h, in women 0.10 +/- 0.04 h, the elimination half-life (t1/2 beta) 1.85 +/- 0.28 h, respectively, 1.94 +/- 0.34 h and the total body clearance (CL) 33.2 +/- 11.8 l.h-1, and, respectively, 22.18 +/- 3.10 l.h-1. For these intrinsic pharmacokinetic parameters differences between men and women were not statistically significant. After oral administration, the pharmacokinetic profile was described with a 1-compartment model. The lag time was subject dependent and was significantly longer in men 0.33 +/- 0.09 h than in women 0.09 +/- 0.07 h. T1/2 beta in men was 2.08 +/- 0.43 h and was longer than in women 1.42 +/- 0.31 h (p = 0.012). In both men and women a large variation of bioavailability was shown ranging between 22% and 138%. CONCLUSION This study with oral methylergometrine showed a comparable large interindividual variability in bioavailability in both men and women.