Pituitary down-regulation prior to in-vitro fertilization and embryo transfer: a comparison between a single dose of Zoladex depot and multiple daily doses of Suprefact.

In order to further evaluate the endocrinological, embryological and clinical efficacy of a single injection of the gonadotrophin-releasing hormone (GnRH) analogue Zoladex (goserelin), 142 women underwent pituitary down-regulation prior to in-vitro fertilization and embryo transfer: 71 with a single injection of Zoladex depot (group I) and 71 matched controls with multiple daily injections of Suprefact (buserelin; group II). Ovarian stimulation was performed with human menopausal gonadotrophin (HMG) and ovulation induction with human chorionic gonadotrophin (HCG). HMG and hydroxyprogesterone caproate depot were given for luteal phase support. The mean (+/- SD) age (34.01 +/- 4.42 versus 34.81 +/- 4.00 years), mean total dosage of HMG (61.25 +/- 26.87 versus 56.17 +/- 25.18 ampoules), mean daily dosage of HMG (4.74 versus 4.94 ampoules), duration of HMG stimulation (12.91 +/- 3.68 versus 11.31 +/- 3.46 days) and oestradiol concentration on the day of HCG (10,082 +/- 8007 versus 9440 +/- 7840 pmol/l) were similar in both groups but the mean total number of injections (GnRH and HMG) (13.55 +/- 3.35 versus 55.37 +/- 31.92) was significantly lower in group I. Furthermore, the proportion of women down-regulated by 2 weeks and pregnancy rate per embryo transfer were significantly higher in the Zoladex group, while miscarriage rates were similar. We conclude that a single dose of Zoladex is quicker, more convenient and should be investigated as an equally effective alternative to multiple doses of Suprefact for pituitary down-regulation prior to assisted conception. Further studies are required to test the teratogenicity and effectiveness of Zoladex.