Zoladex (goserelin acetate implant) in the treatment of endometriosis: a randomized comparison with danazol. The Zoladex Endometriosis Study Group

To compare the efficacy, endocrine effects, and safety of Zoladex (goserelin acetate) and danazol in the treatment of premenopausal women with endometriosis in a multicenter, randomized, open study. Three hundred fifteen patients with stages I-IV endometriosis (revised American Fertility Society [AFS] classification) were treated with Zoladex, 3.6 mg every 28 days by subcutaneous injection, or danazol, 400 mg orally twice daily for 24 weeks. Efficacy was assessed by determination of pelvic signs and symptoms scores and revised AFS endometriosis scores. Endocrine effects were determined by measurements of hormone levels. Safety was evaluated by physical examination, laboratory indices, occurrence of adverse events, and bone mineral density changes. Both treatments significantly (P < .0001) reduced mean subjective signs and symptoms scores both during and after therapy. The mean percent reduction in the revised AFS endometriosis score after 24 weeks of treatment was 53% for Zoladex and 33% for danazol, and reduction in the endometrial implants score was 56% for Zoladex and 46% for danazol. Serum estradiol levels decreased to the postmenopausal range in the Zoladex group and to the early follicular phase range in the danazol group. Hypoestrogenic effects occurred more frequently with Zoladex, whereas androgenic side effects were more common with danazol. There was a higher percentage of withdrawals due to adverse events with danazol than with Zoladex. Mean bone mineral density decreased from baseline by 5.4% in the Zoladex group and increased by 1.0% in the danazol group at the end of treatment. Zoladex is as well tolerated and as effective as danazol in the treatment of premenopausal women with endometriosis.