Clinical efficacy and differential inhibition of menstrual fluid prostaglandin F2α in a randomized, double-blind, crossover treatment with placebo, acetaminophen, and ibuprofen in primary dysmenorrhea

ObjectiveThe purpose of this study was to compare acetaminophen with ibuprofen for pain relief and menstrual fluid prostaglandin F2α (PGF2α) suppression in primary dysmenorrhea.Study designTwelve subjects were randomized to placebo, acetaminophen (1000 mg orally, 4 × daily for 3 days) or ibuprofen (400 mg orally, 4 × daily for 3 days), once during each cycle in a prospective, double-blinded, crossover study. Using preweighed super absorbent tampons, menstrual fluid was collected, extracted, and PGF2α radioimmunoassayed.ResultsTen patients completed the study. Ibuprofen (P = .002) and acetaminophen (P = .022) were rated significantly better than placebo. Total menstrual fluid PGF2α with placebo was 36.2 + 6.1 μg but were 14.8 + 3.0 μg with ibuprofen (P = .001) and 21.4 + 3.4 μg with acetaminophen (P = .008). PGF2α concentrations with placebo were 0.34 + 0.054 μg/mL, with ibuprofen 0.16 + 0.026 μg/mL (P = .001), and with acetaminophen 0.23 + 0.029 μg/mL (P = .016).ConclusionBoth ibuprofen and acetaminophen were superior to placebo for pain relief and menstrual fluid PGF2α suppression, with ibuprofen being more potent.