Antispasmodic/analgesic associations in primary dysmenorrhea double-blind crossover placebo-controlled clinical trial.

We studied 125 patients with primary dysmenorrhea in a prospective randomized double-blind crossover study. After an admission pretreatment period without medication, the patients completed three consecutive randomized treatment phases with lysine clonixinate 125 mg plus propinox 10 mg or paracetamol 500 mg plus hyoscine N-butylbromide 10 mg or placebo, according to a fixed-dose schedule of 1 tablet every 6 h, 3 days before onset of menses and for 5 days thereafter. Changes in menstrual pain intensity and duration, amount of bleeding measured according to the number of daily pads used and concomitant symptoms were assessed on the fifth day of each cycle. Every night, the patients recorded the average intensity of menstrual pain during the first 4 days of menstruation in a diary The follow-up visit carried out at day 5 showed significant reduction in pain intensity with both active treatments vs. the other two phases: baseline: 2.72 +/- 0.61; placebo: 1.85 +/- 0.87; lysine clonixinate plus propinox 1.36 +/- 0.81, and paracetamol plus hyosine N-butylbromide: 1.45 +/- 0.87. The patients' diaries showed increasingly lower pain intensities starting from day 1 with the three treatments. Active treatments revealed significantly higher analgesic efficacy from the outset compared with baseline and placebo; however, only the lysine clonixinate plus propinox combination reached a statistically significant difference by days 3 and 4. No changes in duration or intensity of menstrual bleeding or in the incidence of adverse effects were observed during the four study periods.