Local inhibition of myoelectrical activity of human colon by loperamide

In order to study whether the antidiarrheal effects of loperamide are largely brought about by a local inhibition of the drug, we applied doses of 0.2 mg directly on the mucosa of the descending and sigmoid colon of 33 healthy volunteers. Loperamide decreased BER frequencies and reduced spike activity to 6.6 +/- 0.3% of time vs 11.3 +/- 0.7% in the control recorded from 3 cm aside and to 5.8 +/- 0.4% vs 12.7 +/- 0.9% in the descending and sigmoid colon, respectively. The same effects became apparent when spike activity was stimulated by neostigmine. Loperamide also reduced the occurrence of groups of spikes to 3.8 +/- 0.4/hr vs 10.3 +/- 0.6 and to 3.6 +/- 0.4/hr vs 14.6 +/- 0.7 in the descending and sigmoid colon, respectively. Groups of spikes are thought to be the equivalent of propulsive movements. Thus, loperamide is active locally and exhibits inhibitory effects on the motor activity of the colon. Clinical studies seem warranted to examine the effectiveness of loperamide enemas in motility disturbances of the anorectum.