Methylnaltrexone: Investigation of clinical applications

Morphine and related opioids are widely used medications that are associate d with a number of limiting side effects. In the last three decades signifi cant progress has been achieved in our understanding of the mechanisms of a ction of these opioids; however, these advances have yielded few new approa ches to the management of opioid side effects. Methylnaltrexone, the first peripheral opioid antagonist currently under clinical investigation, has th e potential to prevent or treat opioid-induced peripherally mediated side e ffects without interfering with analgesia. This article reviews data obtain ed from preclinical and clinical studies on methylnaltrexone that focus on the antagonism of opioid-induced constipation. Other potential clinical app lications of the compound are also discussed. (C) 2000 Wiley-Liss, Inc.