The synergistic effects of clomiphene citrate and human menopausal gonadotrophin in the folliculogenesis of stimulated cycles as assessed by the gonadotrophin-releasing hormone antagonist Nal-Glu.

Clomiphene citrate (CC), alone or in combination with exogenous gonadotrophins, has been widely used in ovulation induction. CC promotes endogenous release of gonadotrophins, yet when used in combination with exogenous gonadotrophins, its contribution to folliculogenesis is difficult to assess. In order to determine the contribution of CC-induced endogenous gonadotrophin production to the overall ovarian stimulation in cycles treated with CC/human menopausal gonadotrophin (HMG), Nal-Glu, a gonadotrophin-releasing hormone (GnRH) antagonist was administered. Fertile women (n = 10) undergoing ovarian stimulation and oocyte aspiration for the sole purpose of gamete donation were studied. Five women received CC (100 mg daily for 5 days) in conjunction with pure follicle stimulating hormone (FSH) 150 IU daily. Five women received HMG alone. Nal-Glu (50 micrograms/kg/day) was administered intramuscularly to both groups when the leading follicles reached a mean diameter of 16 mm. Human chorionic gonadotrophin (HCG) 10,000 IU was given when the largest follicles reached a mean diameter of 20-22 mm. A significant fall in serum oestradiol levels was observed in women given CC/FSH (37.9 +/- 7.3%) within the first 24 h of Nal-Glu administration. Serum luteinizing hormone (LH) decreased greater than 20% within 24 h of Nal-Glu administration and remained low throughout the rest of the treatment. No decrease in oestradiol levels was noted in cycles receiving HMG alone. With supplemental FSH, falling oestradiol levels in CC/FSH cycles rebounded and continued to rise until the day after HCG administration. Despite a drop in oestradiol in CC/FSH cycles, the aspirated oocytes exhibited no untoward effects. The fertilization and cleavage rates were similar, and pregnancies occurred in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)