A Dose-ranging Study to Determine the Efficacy and Safety of 1, 2, and 4mg of Dienogest Daily for Endometriosis

Objectives: To compare the efficacy and safety of dienogest at doses of 1, 2, and 4mg/day orally in the treatment of endometriosis.

Methods: An open-label, randomized, multicenter, 24-week comparative trial in women with histologically confirmed endometriosis. Efficacy was assessed by second-look laparoscopy and patient-reported symptoms. Statistical tests included chi(2) and Wilcoxon signed rank tests.

Results: Dienogest reduced mean revised American Fertility Society scores from 11.4 to 3.6 (n=29; P<0.001) in the 2-mg group and from 9.7 to 3.9 (n=35; P<0.001) in the 4-mg group. Dienogest at 2 and 4mg/day was associated with symptom improvements in substantial proportions of women. Both dienogest doses were generally well tolerated, with low rates of treatment discontinuation due to adverse events. The 1-mg dose arm was discontinued owing to insufficient bleeding control.

Conclusion: Dienogest at 2mg once a day is recommended as the optimal dose in future studies of endometriosis.