Insights Into the Diagnosis and Treatment of Opioid- Induced Constipation

• Published in: The clinical advisor 2019-03, Vol.22 (3), p.14-19
• Main Authors: Giannelli, Frank R, Patel, Sarah
• Format: Magazinearticle
• Language: English
• Subjects: Cancer; Constipation; Laxatives; Lifestyles; Medical diagnosis; Narcotics; Pain; Patient satisfaction; Polyethylene glycol; Prevention
• ISSN: 1524-7317

In 2018, the American Gastroenterological Association (AGA) issued new guidelines for the management of OIC.8 The approach to treatment of OIC includes the use of modalities that address non-opioid-related constipation as well as several relatively new medications that specifically target the OIC mechanism of action.1 Pathophysiology Opioids affect the gastrointestinal (GI) system by binding to 3 types of receptors: delta (8), kappa (κ), and mu (p) receptors; of these, p receptors are primarily responsible for the gastrointestinal adverse effects associated with opioids including constipation, nausea, and vomiting.9 When opioids bind to p receptors in the gut, they inhibit the enteric neural system by blocking adenylate cyclase, thereby reducing acetylcholine release, which decreases smooth muscle contraction.9'10 In addition, opioids cause increased water reabsorption in the gut leading to firm, dry stool.9,11 OIC is unique because unlike other GI-related adverse effects of opioids, patients do not develop tolerance to the constipation, making the need for further intervention necessary.10 Clinical Presentation and Diagnosis Patients who develop OIC present similarly to patients with chronic idiopathic constipation; however, the symptoms begin following the initiation of opioid therapy. The risk of developing constipation in the setting of opioids increases with a longer duration of use; however, patients can still develop symptoms when opioids are used for a short period of time.12 As defined by the Rome IV criteria, diagnostic criteria for OIC include new or worsening symptoms of constipation when initiating, changing, or increasing opioid therapy.13 Symptoms must include 2 or more of the following: fewer than 3 spontaneous bowel movements per week, straining, lumpy or hard stools, sensation ofincomplete evacuation, sensation ofanorectal obstruction/blockage, or manual maneuvers to facilitate defecation during more than 25% of bowel movements.13 Other symptoms of OIC may include abdominal pain or distention, gas or bloating, and nausea.6 Clinicians must evaluate for red flag signs and symptoms such as weight loss, loss of appetite, blood in the stool, severe symptoms, failure to respond to therapy, or iron deficiency anemia that may warrant further evaluation before making a diagnosis. Two open-label studies have evaluated the efficacy of laxatives in OIC.15,16 Twycross et al demonstrated a 75% response rate to a stimulant laxative in cancer patients wi