Can Opioid Induced Effects on Esophageal Motility and Lower Esophageal Sphincter be Counteracted by a Dopamine Receptor Antagonist?

Opioids induce pharyngeal and esophageal dysfunction and reduce the lower esophageal sphincter (LES) pressure, and thereby decreases the barrier pressure between the stomach and esophagus. This contributes to an increased risk of regurgitation and aspiration during anaesthesia induction and in the postoperative period, when the patient is treated with opioids for pain relief.

The effect of opioid antagonists on the opioid induced pharyngeal dysfunction and lower esophageal sphincter pressure are unknown. In a recently performed clinical trial we found that the peripheral opioid antagonist methylnaltrexone didn't have effect on the pharyngeal induced pharyngeal and esophageal dysfunction.This indicates that the negative opioid induced effects are not peripherally induced or mediated via peripheral opioid receptors.

In previously performed studies most of the volunteers reported swallowing problems when receiving infusion of the opioid remifentanil, we have also found that remifentanil abolished spontaneous esophageal motility.

The purpose of the study is to evaluate if opioid induced effects on the lower esophageal sphincter can be counteracted by a dopamine receptor antagonist, metoclopramide. It is previously known that dopamine, a catecholamine neurotransmitter, decreases the lower esophageal sphincter pressure and that a dopamine antagonist has the ability to increase the pressure.

Further in this study we want to evaluate if the opioid antagonist naloxone, which affects both peripheral and central opioid receptors, reduces the opioid induced pharyngeal and esophageal dysfunction.