RESUMEN
Traditionally, therapeutic preparations of gonadotrophins are quantified with a rat in-vivo bioassay in biological international units (IU). This method was developed to cope with variability of production batch quality. The bioassay, however, presents some limitations, and differences in clinical responses when using different batches of urine-derived gonadotrophins have been reported. The production of human FSH by recombinant technology now allows the use of advanced physicochemical methods for quantifying FSH, which can be measured in microg of FSH proteins (in mass). The study reported here was designed and conducted to assess the clinical relevance of this new method for quantifying therapeutic preparation of FSH. Four bulk lots of recombinant human FSH (r-hFSH) were used to prepare batches filled by IU (FbIU) and four batches filled by mass (FbM). These eight batches were compared in a double-blind, randomized study in patients undergoing assisted reproductive technology. One hundred and thirty-one patients were enrolled in this study and met protocol criteria (66 in the FbM group and 65 in the FbIU group). The starting dose of recombinant human FSH (r-hFSH) was either 150 IU or 11 microg/day. Both preparations induced multiple follicular development and all patients underwent oocyte retrieval. The number of follicles >/= 11mm was 14.85 and 14.91, serum oestradiol concentration on day of human chorionic gonadotrophin (HCG) administration was 6524 and 6350 pmol/l, number of oocytes retrieved was 10.76 and 11.28, number of two-pronuclear (2 PN) oocytes was 5.2 and 5.00, number of viable embryos (replaced or cryopreserved) was 4.15 and 3.72, and clinical pregnancy rate was 30.3 and 26.2% respectively in the FbM and FbIU groups. Overall, the patients' response consistency was found to be superior with FbM (P = 0.039), and in particular for clinical pregnancy rates (P < 0.001). This new method for quantifying r-hFSH delivers an improved consistency in clinical outcome.