Pharmacokinetics and follicular dynamics of corifollitropin alfa versus recombinant FSH during ovarian stimulation for IVF

A single injection of corifollitropin alfa can replace seven daily injections of recombinant FSH (rFSH) using a gonadotrophin-releasing hormone antagonist protocol in ovarian stimulation prior to IVF or intracytoplasmic sperm injection. This double-blind randomized controlled trial assessed the pharmacokinetics and pharmacodynamics of 150 μg corifollitropin alfa versus daily 200 IU rFSH in 1509 patients. Comparative analyses were performed on serum concentrations of FSH immunoreactivity (pharmacokinetics), and the number and size of growing follicles, and inhibin B and oestradiol concentrations as biomarkers of ovarian response (pharmacodynamics). The rate of follicular development was similar in both treatment groups. By stimulation day 8, 33% of patients treated with corifollitropin alfa reached the criterion for human chorionic gonadotrophin (HCG) injection. The number of follicles ≥11 mm was slightly higher after corifollitropin alfa compared with daily rFSH at stimulation day 8 (difference, 1.2; 95% confidence interval (Cl) 0.5−1.8; P < 0.01) and on the day of HCG injection (difference, 2.1; 95% Cl 1.4−2.8; P < 0.01). The rise of inhibin B and oestradiol concentrations was similar in both treatment groups. Although the pharmacokinetics of corifollitropin alfa and rFSH are quite different their pharmacodynamic profiles at the dosages used are similar.