Lower esophageal sphincter response to oral administration of cimetidine in normal subjects

Anithistamines that specifically block the gastric and secretory action of histamine have recently been developed. One of these H2-receptor blockers, metiamide, has been found to increase lower esophageal sphincter (LES) pressure in the opossum. Because of reported agranulocytosis with metiamide, another H2-receptor blocking agent, cimetidine, was developed. To determine its effect on LES pressure, 8 normal volunteers received placebo or oral doses of cimetidine (50, 100, 200, and 400 mg) in a random, blinded manner. Indicative of adequate absorption, significant serum levels were achieved with all doses of cimetidine (50 mg = 0.17 mug per ml; 100 mg = 0.33 mug per ml; 200 mg = 0.76 mug per ml; and 400 mg = 1.61 mug per ml). Although these serum levels have been found to produce marked inhibition of gastric acid secretion, no discernible effect was found on LES pressure when compared to placebo. Thus cimetidine does not increase LES pressure. It does not decrease sphincter pressure either and is therefore not contraindicated in patients with reflux esophagitis.