Efficacy of mefenamic acid in patients with a complaint of menorrhagia.

Sixty-nine patients with a convincing history of menorrhagia completed a 4-cycle double-blind randomized placebo-controlled crossover trial of mefenamic acid taken during menstruation. Only 30 of these patients demonstrated objective menorrhagia with a measured menstrual loss greater than 80 ml during the placebo cycles, but the remainder reported passing clots and/or using 2 pads at a time. Fourteen of these women (20%) had a loss of less than 35 ml while taking placebos. This raises serious questions about the establishment of menorrhagia based on history alone. Overall, there was a mean reduction of 28.1% in menstrual blood loss between placebo and mefenamic acid cycles (P less than .001). The greatest reduction recorded was 80%, and most of the large percentage reductions were seen in patients with high loss during placebo cycles. Significant reductions in blood loss (P less than .001) were seen in patients with ovulatory dysfunctional uterine bleeding and menorrhagia that developed after tubal interruption. There was also an indication based on small sample sizes that mefenamic acid reduced blood loss in women with anovulatory dysfunctional uterine bleeding, fibroids, intrauterine devices, and von Willebrand disease. No reduction was seen during the mefenamic acid cycle in the group with a loss of less than 35 ml during the placebo cycle. There was a significant shortening of duration of bleeding (P less than .003). Fifteen patients (21.7%) experienced no objective reduction in blood loss.