Will GnRH antagonists assist in the treatment of benign gynaecological diseases?

While GnRH agonists have become well-established tools for preoperative treatment of uterine fibroids or postoperative treatment in endometriosis for 3-6 months, GnRH antagonists seem to offer important advantages due to their specific pharmacological mode of action. Avoiding any flare-up effect, it seems to be possible to reduce treatment time to about only 2-4 weeks in the case of fibroids to obtain a clinically relevant reduction in size. Furthermore, due to the classic competitive receptor blockade induced by GnRH antagonists, it is feasible to preserve residual oestradiol secretion for a period of 8 weeks in patients with endometriosis. Endometriosis patients undergoing this treatment reported a symptom-free period, with no signs of mood changes, hot flushes, loss of libido, vaginal dryness or other symptoms. Serum oestradiol oscillated around a mean level of 50 pg/ml during therapy. Sequential administration of the GnRH antagonist cetrorelix (Cetrotide), in a 3 mg dosage once weekly over 8 weeks in the case of endometriosis or administration every 4th day for a time span of 2-4 weeks for fibroids, creates a new opportunity for medical treatment. Although 3 mg of cetrorelix acetate obviously acts as an intermediate depot preparation, results obtained so far are very preliminary.