methylnaltrexone and Coronary-Disease

Transient impairment of bowel function is a frequent and distressing problem in neonates on opioid-induced analgesia. Methylnaltrexone, a peripheral-acting μ-opioid receptor antagonist, has been studied in adults for the treatment of opioid-induced constipation in advanced illness and has been suggested as a promising therapeutic concept for reducing postoperative ileus. Here, we report on a newborn infant on fentanyl analgesia after major abdominal surgery with aggravated ileus. After 8 days of quiescent bowel, the patient's intestinal dysmotility resolved within 15 minutes after intravenous administration of methylnaltrexone (0.15 mg/kg body weight). Methylnatrexone was repeated daily until cessation of fentanyl administration. There were no signs of pain or opioid withdrawal.

Topics: Aortic Arch Syndromes; Coronary Disease; Extracorporeal Membrane Oxygenation; Fatal Outcome; Female; Fentanyl; Humans; Infant, Newborn; Intestinal Pseudo-Obstruction; Naltrexone; Narcotic Antagonists; Narcotics; Pain, Postoperative; Postoperative Complications; Quaternary Ammonium Compounds; Remission Induction

Ventricular arrhythmias are an important cause of death after myocardial ischaemia. Animal studies have generated conflicting data on the potentiating or attenuating effects of opioid agonists and antagonists on cardiac rhythm during acute myocardial ischaemia and coronary artery reperfusion. Whether these effects of opioid antagonists are mediated by central or peripheral nervous system mechanisms remains unclear. We examined (a) the effects of peripheral opioid receptor blockade on ischaemia-induced arrhythmia by using methylnaltrexone (MNTX), a novel quaternary derivative of naltrexone (NTX) that does not cross the blood-brain barrier, and (b) whether MNTX would modulate morphine effects during acute coronary artery ligation and reperfusion in the rabbit. The incidence and severity of cardiac arrhythmias were assessed during 40 min of coronary artery occlusion and reperfusion and summarised in an arrhythmia score (AS). MNTX reduced the incidence of ventricular fibrillation (VF) and arrhythmia score during coronary artery occlusion when compared with vehicle (p < 0.05). Naltrexone reduced the incidence of VF (p < 0.05). Although morphine alone had no significant effects, its coadministration blunted the antiarrhythmic properties of MNTX. The data suggest that blockade of opiate receptors outside the central nervous system may protect against ischaemia-induced arrhythmias.

Topics: Animals; Arrhythmias, Cardiac; Blood Pressure; Cardiovascular System; Coronary Disease; Drug Interactions; Heart Rate; Morphine; Myocardial Reperfusion Injury; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Rabbits