Pharmacokinetics of recombinant human follicle stimulating hormone after intravenous, intramuscular, and subcutaneous administration in monkeys, and comparison with intravenous administration of urinary follicle stimulating hormone.

Recombinant human follicle stimulating hormone (r-hFSH; Gonal-F) is a new human FSH produced by a genetically engineered mammalian cell line (Chinese Hamster Ovary cells). To assess and compare its pharmacokinetics with urofollitropin (u-hFSH; Metrodin), extracted from the urine of postmenopausal women, we performed a cross-over study in 12 monkeys. They received 10 IU/kg iv of u-hFSH and r-hFSH. Then all received a single 10 IU/kg dose im and sc of r-hFSH. In the third phase, six monkeys received 10 IU/kg/day im of r-hFSH for 7 days when the six others received the same regimen subcutaneously. Blood was withdrawn at predetermined time points, and FSH serum concentrations were measured by an immunoenzymetric assay. Data were analyzed individually by fitting a two-compartment pharmacokinetic model for the intravenous routes and a one-compartment first-order absorption model for the intramuscular and subcutaneous routes. After intravenous administration of u-hFSH and r-hFSH, mean FSH concentration-time curves were almost parallel. AUC0-infinity was significantly smaller after r-hFSH (846 IU.hr-1/liter +/- 125) than after u-hFSH (1377 IU.hr-1/liter +/- 236) (p