, Volume 37, Issue 6, pp 919-924

Effect of verapamil on human intestinal transit

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Although constipation is a well-known side effect of calcium channel blockers such as verapamil, this side effect has not been evaluated in a quantitative manner. In a double-blind, randomized, crossover trial, the effect of verapamil (240 mg/day) was compared to placebo in 15 normal male volunteers. Subjects recorded their bowel movements and any side effects. Scintigraphy was used to quantitate gastric emptying, small intestinal transit, and colonic transit. In the study period of four days, verapamil did not change the frequency, consistency, or passage of bowel movements. A significantly increased number of side effects was noted during verapamil treatment—notably abdominal pain and dry mouth. The slope of gastric emptying was not significantly different for verapamil (0.012±0.02) than for placebo (0.013±0.001). Distal ileum filling was also not different for verapamil (0.41±0.13%/min) than placebo (0.33±0.05%/min). Progression of the colonic geometric center was significantly delayed at 48 hr by verapamil (5.2±0.4 vs 6.2±0.23;P<0.01). This study suggests that the constipating effect of verapamil is due to a delay of colonic transit and not due to an effect on upper gastrointestinal transit.

This work was presented in part at the annual meeting of the American Gastroenterological Association in May 1991.
This research was supported in part by a grant from the R. W. Johnson Pharmaceutical Research Institute, and by Biomedical Research Support Grant S07 RR05417 from the Division of Research Resources, National Institutes of Health, U.S. Public Health Service.