In vitro effects of famotidine and ranitidine on lower esophageal sphincter tone in rats.

BACKGROUND/AIMS The aim of this study was to investigate the effects of the H2 receptor antagonists famotidine and ranitidine on lower esophageal sphincter pressure in the rat isolated lower esophageal sphincter preparation contracted with carbachol. MATERIALS AND METHODS Lower esophageal sphincter tissues of eight rats for each group were placed in a standard organ bath. After contraction with carbachol, freshly prepared famotidine and ranitidine were added directly to the tissue bath in cumulatively increasing concentrations. Activities were recorded on an online computer using the software BSL PRO v 3.7, which also analyzed the data. RESULTS Ranitidine caused a small statistically insignificant relaxation in the contracted lower esophageal sphincter at the two applied concentrations. Although 1.5 x 10⁻⁵ M famotidine did not cause a significant relaxation in lower esophageal sphincter tone, this value for 4.5 x 10⁻⁵ M famotidine was 9.33%, and the relaxation was significant when compared with controls (p<0.05). CONCLUSIONS Neither famotidine nor ranitidine caused any direct significant change in lower esophageal sphincter tone in the therapeutic dose range applied to the organ bath. However, the higher dose of famotidine caused a significant relaxation in the lower esophageal sphincter tone. Further in vivo human studies may affect the usage of these drugs during gastroesophageal reflux disease treatment.