Pethidine, metoclopramide and the gastro-oesophageal sphincter. A study in healthy volunteers.
The effects of intramuscular pethidine (1.0--3.0 mg/kg) followed by metoclopramide 10 mg intravenously, and those of a combination of pethidine 1.5 mg/kg and metoclopramide 10 mg given intramuscularly, on the lower oesophageal sphinct pressure have been studied manometrically in human volunteers. In the former group, the mean effect of all the doses of pethidine was a reduction of the lower oesophageal barrier pressure by 6.8 cmH2O from control values (p less than 0.0002), while the intravenous administration of metoclopramide resulted in a mean increase in barrier pressure of 8.75 cmH2O above the depressed level (p less than 0.0001). Following the combination of pethidine and metoclopramide given intramuscularly depression of the sphincter pressure was not totally prevented, but there was a reduction in its incidence and severity. It is suggested that pethidine is likely to increase the possibility of gastro-oesophageal reflux, and that metoclopramide is a useful adjunct in the prevention of reflux in preparation for, and after, surgery in patients who have been given pethidine for pain relief.