The 24-h progression of menstrual pain in women with primary dysmenorrhea when given diclofenac potassium: a randomized, double-blinded, placebo-controlled crossover study

Primary dysmenorrhea, which refers to painful, spasmodic cramping in the lower abdomen just before/or during menstruation, is the most common gynecological complaint in women of reproductive age. Non-steroidal anti-inflammatory drugs have been prescribed as the first-line therapy for pain relief from dysmenorrhea. We aimed to investigate the efficacy of the daily recommended dose (150 mg) of diclofenac potassium, administered at set intervals across the first 24 h of menstruation, in treating severe menstrual pain in 24 women with severe primary dysmenorrhea. In a randomized, placebo-controlled, double-blind cross-over study, women rated their menstrual pain intensity on a 100-mm visual analog scale across set time intervals over a 24-h period. Menstrual pain intensity was significantly reduced after taking the first capsule of diclofenac, and remained consistently lower (P < 0.0001), compared with initial pain intensity, in the morning (before treatment), throughout the day, evening, and into the next morning. Also, women rated their pain intensity as significantly lower (P < 0.001) at each time point across the 24-h time interval of the cycle when receiving diclofenac compared with the cycle when they received placebo. No woman required rescue medication when taking diclofenac potassium compared with six women taking rescue medications during the placebo trial. When taking only placebo, women rated their menstrual pain intensity as persistently severe across the first 24 h of menstruation. These results show that the recommended daily dose of diclofenac potassium, in three 50 mg doses across the day and evening, offers effective menstrual pain relief across 24 h, compared with placebo, in women with severe primary dysmenorrhea.