Effect of nifedipine on rectoanal motility

Based on the rationale that the calcium channel blocker, nifedipine, decreases lower esophageal sphincter pressure in achalasia, a prospective controlled trial was performed to evaluate the effect of sublingual nifedipine on the anal sphincter of controls and patients with high anal resting pressures.

Ten age-matched and sex-matched controls without evidence of anal disorder and ten patients with hemorrhoids and/or fissure-in-ano were included in the study. Anorectal manometry, with an eight-channel, water-perfused catheter was performed on all patients before and 30 minutes after administration of 20 mg of sublingual nifedipine.

Nifedipine significantly reduced anal resting pressure in both controls and patients by approximately 30 percent (P < 0.001 and P < 0.0001, respectively). A significant reduction was also noted in the length of high-pressure zone of the anal sphincter (P < 0.02 for both groups) and in the frequency (controls, P < 0.05; patients, P < 0.03) and amplitude (controls, P < 0.03; patients, P < 0.009) of slow waves in both groups, whereas the presence, frequency, and amplitude of ultraslow waves were significantly reduced only in the patient group (P < 0.05; P < 0.01; P < 0.0005, respectively).

Nifedipine reduces the activity of the internal anal sphincter both in controls and patients with high anal resting pressure. The drug might be of some use in relieving symptoms in patients with hemorrhoids or anal fissure.