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.