A double-blind, placebo-controlled, 6-day evaluation of two doses of misoprostol in gastroduodenal mucosal protection against damage from aspirin and effect on bowel habits.

Ninety-one normal, healthy volunteers participated in a single-center, double-blind, placebo-controlled, randomized, parallel group study: 1) to compare the prostaglandin E1 analog, misoprostol, given at a dose of 200 micrograms bid, with the recommended dose of 200 micrograms qid in protecting the gastroduodenal mucosa against injury due to anti-inflammatory doses of aspirin (3900 mg/day); and 2) to determine whether the reduced dose was associated with a lesser incidence of gastrointestinal (GI) side effects, particularly diarrhea. All subjects received 975 mg of aspirin qid with meals and at bedtime. They were concurrently administered either misoprostol 200 micrograms qid, misoprostol 200 micrograms bid and placebo bid, or placebo qid. All subjects were endoscopically normal at the onset of the study and were re-endoscoped on the morning of the 7th day of therapy, 2 h after the morning dose of medications. Gastric and duodenal mucosa were assessed separately on a 0-7 scale which gave a greater weight to erosions than to hemorrhages. GI symptoms, especially bowel habits, were assessed by means of diary cards. Subjects in both misoprostol groups had significantly less gastric and duodenal mucosal injury than subjects who received placebo (p less than 0.007 for each pairwise comparison). There was no statistically significant difference between the two misoprostol groups (p less than 0.093). Subjects in the misoprostol 200 micrograms qid group had significantly more loose and watery bowel movements than the subjects in the misoprostol 200 micrograms bid group (p less than 0.013), whereas there were no significant differences in bowel habits between the misoprostol 200 micrograms bid and placebo groups (p less than 0.122). More subjects in the misoprostol 200 micrograms qid group reported abdominal pain, loose stools, watery stools, flatulence, dyspepsia, and nausea than in the misoprostol 200 micrograms bid and placebo groups. In conclusion, the adverse events in the misoprostol 200 micrograms bid group were not significantly different from those in the placebo group, and were significantly better than in the misoprostol 200 micrograms qid group. The lower dose retained mucosal protective activity that was statistically indistinguishable from that of misoprostol 200 micrograms qid.