Evaluation of the combined effects of atropine and domperidone on the lower oesophageal sphincter.

The effects of sequential administration of both domperidone followed by atropine, and atropine followed by domperidone were examined on the lower oesophageal sphincter of 10 healthy volunteers. Domperidone, 10 mg, increased lower oesophageal sphincter pressure (LOSP) within 10 min of injection. Atropine, 0.6 mg given at the time of peak effect of domperidone, subsequently decreased LOSP. However, frequent measurement of LOSP during the succeeding 40 min demonstrated that LOSP did not decrease significantly below control levels during this drug sequence. When the drugs were administered in the reverse sequence, atropine, 0.6 mg, decreased LOSP within 5 min of injection and subsequent administration of domperidone, at the time of peak effect of the atropine, resulted in a gradual increase in LOSP. However, control values were not approached until 30 min had elapsed after the administration of the domperidone.