COMPARISON OF THE SUPPRESSIVE CAPACITY OF DIFFERENT DEPOT GONADOTROPIN-RELEASING-HORMONE ANALOGS IN WOMEN

Different depot GnRH analogs (GnRH-A) are currently used for the rever sible suppression of the pituitary-ovarian axis in several reproductiv e and neoplastic disorders in women. In spite of anecdotal reports of incomplete suppression by some depot GnRH-A, this issue has never been systematically investigated in adult women. Thus, we elected to study 40 normally cycling women with male-related infertility or benign rep roductive disorders; each group of 10 subjects received a different Gn RH-A for 3 months: buserelin (group B; 300 mug, sc, every 12 h, as a c ontrol), goserelin (group G; 3.6 mg, sc, every 28 days), leuprorelin ( group L; 3.75 mg, im, every 28 days), and triptorelin (group T; 3.75 m g, im, every 28 days). Depot GnRH-A was administered by one of the inv estigators. GnRH tests (100 mug, iv) were performed before treatment ( cycle day 7; test A) and on treatment days 57 (i.e. 1 day after the th ird depot GnRH-A; test B) and 84 (i.e. 28 days after the third depot G nRH-A; test C). Immunoreactive (i) LH levels were measured with an ult rasensitive immunochemiluminometric assay. Profound suppression of the iLH response to the GnRH test occurred in all subjects during treatme nt. Conversely, FSH levels in the third month of treatment tended to b e higher in the depot GnRH-A groups than in group B, and this differen ce achieved statistical significance (P < 0.05) in groups G and L duri ng test C. In GnRH test B, while the mean estradiol (E2) level was les s than 75 pmol/L (<20 pg/mL) in all group B subjects, individual E2 le vels were greater than 75 pmol/L in five patients receiving depot GnRH -A (two in group G, one in L, and two in T). Finally, individual E2 le vels during test C were greater than 75 pmol/L in only two patients of group G, who also reported vaginal spotting. Thus, we conclude that i n adult women, 1) iLH was profoundly suppressed in the third month of administration of all GnRH-A tested; 2) FSH suppression with depot GnR H-A was less marked than that with high-dose short-acting sc buserelin ; and 3) signs of an incomplete block of ovarian function can be prese nt in the third month of depot GnRH-A administration, particularly whe n goserelin is employed.