TREATMENT OF UTERINE FIBROIDS WITH A SLOW-RELEASE FORMULATION OF THE GONADOTROPIN-RELEASING-HORMONE ANTAGONIST CETRORELIX

A depot preparation of the third-generation gonadotrophin-releasing ho rmone (GnRH) antagonist Cetrorelix (SB-75) was used for preoperative t reatment in twenty premenopausal patients with symptomatic uterine fib roids who were to undergo surgery. In a prospective, open, randomized setting 60 mg of Cetrorelix pamoate salt was administered i.m. on cycl e day 2, Patients were randomized for a second dose of 30 or 60 mg of Cetrorelix depot, which was administered according to the degree of oe stradiol suppression (<50 pg/ml) on treatment day 21 or 28. Surgery wa s done after 6 or 8 weeks of treatment, depending on second dosage adm inistration, Weekly transvaginal sonography (TVS) and magnetic resonan ce imaging (MRI) before and after treatment was performed, for fibroid volume assessment. Sixteen patients showed satisfactory suppression o f gonadotrophins and sex steroid secretion, avoiding any initial flare -up effect. In these patients a mean shrinkage rate of largest fibroid volume of 33.5% at the end of treatment could be observed according t o TVS, while the mean shrinkage rate obtained after 14 days of treatme nt was 31.3%. In good responders (shrinkage >20%) largest fibroid volu me at day 14 was similar to 56.7% of basic assessment. Although MRI sh owed minor mean shrinkage rates of only 25.4% of the initial volume, t hese differences in comparison to TVS assessment were not statisticall y significant. The avoidance of any initial flare-up in gonadotrophin secretion may explain this extremely fast reduction in fibroid size, T he advantages of GnRH antagonist treatment in this indication consist in the short treatment time with a fast restoration of the ovarian fun ction, The rate of poor responders may be reduced by using an improved slow release preparation.