Dose-response analysis of effects of tibolone on climacteric symptoms

Objective To assess the clinically optimal tibolone dose for the relief of climacteric complaints. Design A randomised, double blind, placebo-controlled trial. Setting Twenty-eight centres in Norway, The Netherlands, Sweden and Finland. Population Seven hundred and seventy-five healthy postmenopausal women were randomised to tibolone in a daily dose of 0.625, 1.25, 2.5 or 5.0 mg or placebo for 12 weeks. Methods At baseline, and after 4, 8 and 12 weeks, hot flushes, sweating, vaginal bleeding and adverse experiences were recorded. Main outcome measures Change in frequency and intensity of hot flushes and sweating over 12 weeks. Results From week four onwards, 2.5 and 5.0 mg tibolone were significantly more effective than placebo, regarding the frequency of hot flushes and sweating (P < 0.001), whereas the 0.625 mg dose was not significantly different from placebo during the study. The frequency of hot flushes with the 1.25 mg dose was statistically significantly different from placebo, only from week eight onwards. The incidence of dropouts due to insufficient therapeutic effect was much higher in the tibolone 1.25 mg group (9.5%) than in the 2.5 (1.9%) and 5.0 mg (1.3%) groups. A dose-related increase in incidence of vaginal bleeding or spotting was observed (P < 0.0001). Bleeding incidence in the 5.0 mg dose group was about twice as high as in the 2.5 mg dose group. There was no difference in incidence of adverse experiences between the 2.5- and the 1.25 mg dose group. Conclusion A daily dose of 2.5 mg tibolone is the clinically optimal dose for the treatment of climacteric complaints in postmenopausal women.