Phenelzine and Morphine Drug-Drug Interaction? A Literature Review

The objectives of this manuscript are to describe a case report of a patient whose phenelzine maintenance therapy was discontinued due to concern for a phenelzine-morphine drug interaction, to review the available literature regarding the potential for this drug-drug interaction, and provide recommendations for this clinical scenario. A PubMed/MEDLINE literature search was conducted and all publications determined to be relevant to this case report were included. Literature describing in vitro data, case reports/human studies, and review articles concerning the interaction between morphine and monoamine oxidase inhibitors (MAOIs) were included. A total of 14 publications pertinent to the potential phenelzine-morphine interaction were included in this review including 5 in vitro studies, 4 human studies, and 6 review articles detailing the drug interaction profile between opioids and antidepressants. Of these publications, only a single case report of a potential drug interaction between morphine and phenelzine was identified. The literature suggesting a drug interaction between morphine and phenelzine is limited. The combination of phenelzine and morphine, with close monitoring for signs and symptoms of serotonin syndrome, is reasonable for patients with appropriate indications for both agents.