The effect of three cyclo-oxygenase inhibitors on intensity of primary dysmenorrheic pain

Objective: To determine the effect of 3 different cyclo-oxygenase (COX) inhibitors on primary dysmenorrheic pain. Method: Eleven female patients self-medicated with either placebo (sugar), 25 mg of the COX-2 specific inhibitor rofecoxib, 50mg of the nonselective COX inhibitor diclofenac potassium, or 7.5 mg of the COX-2 selective inhibitor meloxicam, over 4 menstrual cycles. Pain was assessed using the McGill Pain Questionnaire and a visual analog scale. Results: The pain response index, present pain index, and visual analog scale were highly correlated as measures of intensity of pain (r = 0.81 to 0.96, P < 0.0001). Rofecoxib and diclofenac potassium both decreased the duration of dysmenorrheic pain compared with placebo (P < 0.001) and with meloxicam (P < 0.01), and were equally effective in improving pain, compared with placebo, after each capsule (P < 0.001). When compared with placebo, both drugs also provided 50% or more pain relief, after each capsule (P < 0.0048). Meloxicam, although superior to placebo, was not as effective as rofecoxib and diclofenac potassium in reducing pain, and when compared with placebo, was associated with providing 50% or more of pain relief only after the third and fourth capsules (P = 0.016). Conclusions: Rofecoxib and diclofenac potassium, when taken in recommended doses, were equally effective in alleviating pain associated with primary dysmenorrhea.