Effect of morphine on gastroesophageal reflux and transient lower esophageal sphincter relaxation.
OBJECTIVE
Morphine increases residual lower esophageal sphincter (LES) pressure during swallow-induced LES relaxation to levels shown experimentally to prevent reflux. The hypothesis that morphine reduces reflux by increasing residual LES pressure during transient LES relaxation was tested in 8 healthy subjects and 8 patients with reflux disease.


METHODS
Esophageal pH, LES, and esophageal pressures were recorded simultaneously during three sequential 30-minute periods, basal, after morphine, and after naloxone, while the stomach was distended by constant infusion of 10% dextrose.


RESULTS
Morphine decreased the number of reflux episodes and the time at pH < 4 in the patients (3.0 +/- 0.5 vs. 6.2 +/- 1.0 [P < 0.02] and 44% +/- 7% vs. 64% +/- 7% [P < 0.05], respectively) but not in the healthy subjects (P = NS). Transient LES relaxation was the major mechanism of reflux, and although morphine did not affect residual LES pressure during transient LES relaxations, it decreased their number markedly in the patients (3.0 +/- 0.5 vs. 6.6 +/- 1.7 [P < 0.05]) and marginally in the healthy subjects (2.1 +/- 0.4 vs. 2.6 +/- 0.4; P = NS). Naloxone completely reversed the effects of morphine.


CONCLUSIONS
Morphine reduces reflux in patients with reflux disease by decreasing the number of transient LES relaxations.
Penagini
R
R
Cattedra di Gastroenterologia, University of Milan-Instituto di Ricovero e Cura a Carattere Scientifico Ospedale Maggiore, Italy.
Bianchi
P A
PA
D000328:Adult; D000368:Aged; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D003679:Deglutition / Q000187:drug effects / Q000502:physiology; D004943:Esophagogastric Junction / Q000187:drug effects* / Q000502:physiology*; D004947:Esophagus / Q000502:physiology; D005260:Female; D005764:Gastroesophageal Reflux / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015994:Incidence; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D009126:Muscle Relaxation / Q000187:drug effects* / Q000502:physiology; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D011312:Pressure
D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D009270:Naloxone; D009020:Morphine