Clinical efficacy and differential inhibition of menstrual fluid prostaglandin F2alpha in a randomized, double-blind, crossover treatment with placebo, acetaminophen, and ibuprofen in primary dysmenorrhea.

OBJECTIVE: The purpose of this study was to compare acetaminophen with ibuprofen for pain relief and menstrual fluid prostaglandin F2alpha (PGF2alpha) suppression in primary dysmenorrhea.

STUDY DESIGN: Twelve subjects were randomized to placebo, acetaminophen (1000 mg orally, 4 x daily for 3 days) or ibuprofen (400 mg orally, 4 x 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 PGF2alpha radioimmunoassayed.

RESULTS: Ten patients completed the study. Ibuprofen (P = .002) and acetaminophen (P = .022) were rated significantly better than placebo. Total menstrual fluid PGF2alpha with placebo was 36.2 + 6.1 microg but were 14.8 + 3.0 microg with ibuprofen (P = .001) and 21.4 + 3.4 microg with acetaminophen (P = .008). PGF2alpha concentrations with placebo were 0.34 + 0.054 microg/mL, with ibuprofen 0.16 + 0.026 microg/mL (P = .001), and with acetaminophen 0.23 + 0.029 microg/mL (P = .016).

CONCLUSION: Both ibuprofen and acetaminophen were superior to placebo for pain relief and menstrual fluid PGF2alpha suppression, with ibuprofen being more potent.