Drug Interaction Report

CONTRAINDICATED: Monoamine oxidase inhibitors (MAOIs) markedly potentiate the action of morphine. Coadministration of narcotic analgesics including morphine in patients treated with MAOIs has rarely resulted in hypotension, respiratory depression, or coma. There appear to be two types of interaction, an excitatory and a depressive one. Symptoms of the excitatory reaction may include agitation, headache, diaphoresis, hyperpyrexia, flushing, shivering, myoclonus, rigidity, tremor, diarrhea, hypertension, tachycardia, seizures, and coma. Death has occurred in some cases. The exact mechanism of interaction is unknown, but may involve excessive serotonergic activity in the central nervous system (i.e., serotonin syndrome). The interaction is unpredictable and has been reported primarily with meperidine or fentanyl and various MAOIs including phenelzine, tranylcypromine, linezolid, moclobemide, and selegiline. Fatal hyperpyrexia and hypertension have also been observed in animal studies with meperidine and phenelzine or furazolidone. In contrast, symptoms of the depressive reaction probably stem from potentiation of CNS effects by MAOIs and include respiratory depression, cyanosis, hypotension, and coma. The interaction is also expected to occur with diamorphine.

MANAGEMENT: The use of morphine including liposomal formulations or diamorphine with MAOIs or other agents which possess MAOI activity (e.g., furazolidone, procarbazine, selegiline), together or within 14 days of stopping a MAOI is considered contraindicated.

CONTRAINDICATED: Naltrexone can antagonize the effects of opioids via competitive inhibition of opioid receptors. Patients receiving naltrexone may not benefit from opioid-containing medications such as cough and cold products, antidiarrheal preparations, and narcotic analgesics. Likewise, patients dependent on opioids may experience withdrawal symptoms when given naltrexone. Following use of naltrexone, patients may have increased sensitivity to opioids.

**Note: This warning does not apply to opioid products that are specifically formulated with naltrexone to deter abuse via snorting or intravenous injection when crushed.**

MANAGEMENT: The use of naltrexone is considered contraindicated in patients receiving opioids or dependent on opioids, including those maintained on opiate agonists (e.g., methadone) or partial agonists (e.g., buprenorphine). Naltrexone should also not be given to patients in acute opioid withdrawal. In an urgent situation when analgesia may be required in a patient who has received full blocking doses of naltrexone, consideration should be given to regional analgesia, conscious sedation with a benzodiazepine, use of non-opioid analgesics, or general anesthesia. If opioid analgesia is required, the amount of opioid needed may be greater than usual, and the resulting respiratory depression may be deeper and more prolonged. A rapidly-acting opioid analgesic that minimizes the duration of respiratory depression is preferred. Clinicians should be aware that reversal of full naltrexone blockade by administration of large doses of opiates can cause histamine release. Therefore, patients may experience non-opioid receptor-mediated effects such as facial swelling, itching, generalized erythema, and bronchoconstriction. Irrespective of the drug chosen to reverse naltrexone blockade, the patient should be monitored closely by appropriately trained personnel in a setting equipped and staffed for cardiopulmonary resuscitation.

GENERALLY AVOID: Alcohol may potentiate the central nervous system (CNS) depressant effects of opioid analgesics including morphine and diamorphine. Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills. In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

GENERALLY AVOID: Consumption of alcohol while taking some sustained-release formulations of morphine may cause rapid release of the drug, resulting in high systemic levels of morphine that may be potentially lethal. Alcohol apparently can disrupt the release mechanism of some sustained-release formulations. The interaction was observed in in vitro studies using a 24-hour morphine formulation (Avinza 30 mg capsule, available in the U.S. from Ligand Pharmaceuticals). When the capsule was mixed with 900 mL of buffer solutions containing ethanol 20% and 40%, the dose of morphine that was released was alcohol concentration-dependent, leading to a more rapid release of morphine. Although the clinical relevance of this finding is unknown, 'dose-dumping' into the bloodstream is conceivable.

MANAGEMENT: Until more information is available, patients taking sustained-release formulations of morphine should not consume alcohol or use medications that contain alcohol. In general, potent narcotics such as morphine or diamorphine should not be combined with alcohol.

GENERALLY AVOID: Foods that contain large amounts of tyramine may precipitate a hypertensive crisis in patients treated with monoamine oxidase inhibitors (MAOIs). The mechanism is inhibition of MAO-A, the enzyme responsible for metabolizing exogenous amines such as tyramine in the gut and preventing them from being absorbed intact. Once absorbed, tyramine is metabolized to octopamine, a substance that is believed to displace norepinephrine from storage granules. Although selegiline is considered a selective inhibitor of MAO-B, the selectivity may not be absolute even at recommended dosages. Rare cases of hypertensive reactions associated with ingestion of tyramine-containing foods have been reported in patients taking the recommended daily oral dose of selegiline. Data for transdermal selegiline indicate that the 6 mg/24 hour dosage may be given safely without dietary restrictions. However, limited data are available for higher dosages.

MANAGEMENT: Patients treated with oral selegiline and transdermal selegiline (greater than 6 mg/24 hour) should preferably avoid consumption of products that contain large amounts of amines and protein foods in which aging or breakdown of protein is used to increase flavor. These foods include cheese (particularly strong, aged or processed cheeses), sour cream, wine (particularly red wine), champagne, beer, pickled herring, anchovies, caviar, shrimp paste, liver (particularly chicken liver), dry sausage, salamis, figs, raisins, bananas, avocados, chocolate, soy sauce, bean curd, sauerkraut, yogurt, papaya products, meat tenderizers, fava bean pods, protein extracts, yeast extracts, and dietary supplements. Caffeine may also precipitate hypertensive crisis so its intake should be minimized as well. At least 14 days should elapse following discontinuation of selegiline therapy before these foods may be consumed. Specially designed reference materials and dietary consultation are recommended so that an appropriate and safe diet can be planned. Patients should also be advised to promptly seek medical attention if they experience potential signs and symptoms of a hypertensive crisis such as severe headache, visual disturbances, difficulty thinking, stupor or coma, seizures, chest pain, unexplained nausea or vomiting, and stroke-like symptoms. The recommended dosages of selegiline should not be exceeded, as it can increase the risk of nonselective MAO inhibition and a hypertensive crisis.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of central nervous system (CNS)-active agents. Use in combination may result in additive CNS depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled against driving, operating machinery, or engaging in potentially hazardous activities requiring mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

GENERALLY AVOID: Coadministration of naltrexone with other agents known to induce hepatotoxicity may potentiate the risk of liver injury. Naltrexone, especially in larger than recommended doses (more than 50 mg/day), has been associated with hepatocellular injury, hepatitis, and elevations in liver transaminases and bilirubin. Other potential causative or contributory etiologies identified include preexisting alcoholic liver disease, hepatitis B and/or C infection, and concomitant usage of other hepatotoxic drugs.

MANAGEMENT: The use of naltrexone with other potentially hepatotoxic agents should be avoided whenever possible (e.g., acetaminophen; alcohol; androgens and anabolic steroids; antituberculous agents; azole antifungal agents; ACE inhibitors; cyclosporine (high dosages); disulfiram; endothelin receptor antagonists; interferons; ketolide and macrolide antibiotics; kinase inhibitors; minocycline; nonsteroidal anti-inflammatory agents; nucleoside reverse transcriptase inhibitors; proteasome inhibitors; retinoids; sulfonamides; tamoxifen; thiazolidinediones; tolvaptan; vincristine; zileuton; anticonvulsants such as carbamazepine, hydantoins, felbamate, and valproic acid; lipid-lowering medications such as fenofibrate, lomitapide, mipomersen, niacin, and statins; herbals and nutritional supplements such as black cohosh, chaparral, comfrey, DHEA, kava, pennyroyal oil, and red yeast rice). Patients should be advised to seek medical attention if they experience potential signs and symptoms of hepatotoxicity such as fever, rash, itching, anorexia, nausea, vomiting, fatigue, malaise, right upper quadrant pain, dark urine, pale stools, and jaundice. Periodic monitoring of hepatic function is advisable.