Mixed Opioid Receptor Agonists as a New Class of Agents for the Treatment of Moderate to Severe Pain

Painmanagement is amajor therapeutic challenge for which opioid analgesics remain the mainstay in the treatment of moderate to severe pain [1-4]. These agents, which have powerful analgesic action, have been used for well over 200 years in spite of their narrow therapeutic index and their participation in deleterious drug-drug interactions. Adverse effects commonly associated with the use of narcotic analgesics include respiratory depression, nausea and vomiting, constipation, bradycardia, hypotension, hallucinations, euphoria, tolerance, dependence, and addiction potential [2,5,6]. The most life-threatening of these adverse effects is respiratory depression, which accounts for a majority of the resulting deaths, linked to the use of narcotic analgesics [2,6].