Literature Review: Opioid-Induced Constipation

Opioids are a major class of analgesics used in the management of acute and chronic pain, including cancer. One of the most common side effects of opioids is constipation, making opioid-induced constipation (OIC) a symptom experienced by the majority of patients taking these medications. The cause of constipation in patients taking opioid therapy is multifactorial. Opioids interfere with normal gastrointestinal (GI) motility by delaying transit, stimulating nonpropulsive motility, segmentation and tone, and the stimulation of sphincters through their effects on enteric neurons, according to a study [Am J Gastroenterol. 2011;106(5):835-842]. OIC results from the binding of opioid agonists to µ-opioid receptors located in the enteric nervous system.

Dietary modifications, lifestyle changes, and laxatives are used in the management of OIC, but their efficacy is limited. A newer approach is the development of a class of drugs called peripherally acting opioid receptor antagonists, which are used to decrease the constipating effects of opioids. Methylnaltrexone bromide and naloxegol are 2 agents in this class. In this literature review, First Report Managed Care identified 3 studies that focused on the causes, consequences, and management of OIC, as well as the efficacy and safety of methylnaltrexone bromide in patients with advanced illness and naloxegol in patients with noncancer pain. This article provides an overview of these studies.