Opioid induced constipation in cancer patients: pathophysiology, diagnosis and treatment

Opioid-induced constipation (OIC) has emerged as a major contributor to morbidity in cancer patients. OIC is common, difficult to treat and causes significant reductions in the quality-of-life of cancer patients. It results from opioid action on gut mu-receptors, which leads to the disruption of bowel motility, mucosal transport and defecation reflexes. Laxatives are cornerstone in the management of OIC despite their relatively limited effectiveness and lack of strong evidence supporting their use. In the past few years, novel therapeutics have emerged for the management of OIC. These include; prokinetic agents, peripherally-acting mu-opioid receptor antagonists (PAMORAs), secretagogues and opioid receptor agonist/antagonist combination tablets. This article will review the mechanism of OIC in cancer patients and describe the novel therapeutic options for its prevention and management.