Effect of mefenamic acid on bowel transit time in healthy adult volunteers

SUMMARY The effect of mefenamic acid on bowel transit time was investigated. Seven healthy adult male subjects of age 39 ± 2.4 years (mean ± S.E.M.) received placebo or mefenamic acid (500 mg t.d.s) orally in randomized order for five days, with a 7-day washout between studies. On the third morning after starting the drug they had a meal containing Redi-Brek and baked beans with radio-opaque markers. Small bowel transit time was measured using breath hydrogen, and whole gut transit time was measured using radio-opaque markers. The small bowel transit times were 160 min (median) with placebo and 50 min with mefenamic acid (P < 0.05). The percentages of appearance of marker in stool within 24 h were 24.9 ± 11.8 (mean± S.E.M.) with placebo and 48.9±11.7 with mefenamic acid (P < 0.05). The times of appearance of twenty-fifth marker in stool were 41.0±4.4h with placebo and 26.9±3.2h with mefenamic acid (P < 0.05). The total weights of faeces in 72 h were 500.9±96.2 g with placebo and 657.1 ± 118.8 g with mefenamic acid (P < 0.05). Mefenamic acid in therapeutic doses (500 mg t.d.s.) accelerated bowel transit time in healthy subjects.