Clinical-pharmacological studies on human menopausal gonadotrophin

Using a randomized, cross-over design, the clinical, pharmacokinetic and pharmacodynamic properties of commercially available gonadotrophin preparations were studied. Following i.v. administration of 150 IU of follicle-stimulating hormone (FSH) in the form of Humegon, Pergonal and Metrodin, the maximum concentrations (CMax) were 27.5, 24.1 and 26.5 IU/l, respectively which were reached after 15.4, 16.9 and 16.9 min (TMax), respectively. The half lives (t1/2) were 1.6, 2.3 and 2.0 h, respectively (fast compartment) and 11, 10 and 7.3 h, respectively (slow compartment). The t1/2 of luteinizing hormone (LH) could only be estimated in a surgically hypophysectomized patient: the fast compartment was 1.2 and 1.3 h after the administration of Humegon and Pergonal, respectively and the slow compartment was 3.3 h in both cases. Marked individual differences of the same type were found in plasma FSH profiles, ovarian images and peripheral oestradiol levels after the administration of both preparations (150 IU daily for 8 days) and the approximate t1/2 of FSH exceeded 40 h. It is concluded that the pharmacokinetic and pharmacodynamic properties of the preparations studied are similar, if not identical, and that there are marked individual differences in patient responsiveness, which are unrelated to the preparation administered.