Effect of mefenamic acid on controlling irregular uterine bleeding in DMPA users

The objective of this double-blind, placebo-controlled study was to evaluate the effect of mefenamic acid and placebo on controlling irregular uterine bleeding in depot-medroxyprogesterone acetate (DMPA) users. A total of 48 DMPA users attending the Family Planning Clinic, Chulalongkorn Hospital were studied, all had abnormal bleeding. These participants were randomly divided into two groups. A total of 23 users received mefenamic acid, 500 mg, twice a day for 5 days, and placebos were given to the other 25 in the same manner. Total days of bleeding and spotting and percentage of women in whom bleeding was stopped were analyzed in the first and the fourth week. Percentage of subjects in whom bleeding was stopped during the first week after initial treatment was significantly higher in the mefenamic acid group than the placebo group (69.6%, 40.0%; p < 0.05). During the follow-up period (4 weeks after initial treatment), the mean of the bleeding-free interval during 28 days was found to be 16.1 days in the subjects treated with mefenamic acid and 12.39 days in the placebo group. However, the difference was not statistically significant. From the results of the study, we concluded that mefenamic acid was effective in very short-term control of bleeding during DMPA use, but not effective long-term.