Drug Interactions between morphine / naltrexone and tirzepatide

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.

MONITOR: Glucagon-like peptide-1 (GLP-1) receptor agonists and dual GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptor agonists can delay gastric emptying, which may impact the absorption of concomitantly administered oral medications. Mild to moderate decreases in plasma concentrations of coadministered drugs have been demonstrated in pharmacokinetic studies for some GLP-1 receptor agonists (e.g., exenatide, lixisenatide), but not others. According to the prescribing information, liraglutide did not affect the absorption of several orally administered drugs to any clinically significant extent, including acetaminophen, atorvastatin, digoxin, griseofulvin, lisinopril, and an oral contraceptive containing ethinyl estradiol-levonorgestrel. Likewise, no clinically relevant effect on absorption was observed for concomitantly administered oral drugs studied with albiglutide (digoxin, ethinyl estradiol-norethindrone, simvastatin, warfarin), dulaglutide (acetaminophen, atorvastatin, digoxin, ethinyl estradiol-norelgestromin, lisinopril, metformin, metoprolol, sitagliptin, warfarin), or semaglutide (atorvastatin, digoxin, ethinyl estradiol-levonorgestrel, metformin, warfarin). The impact of dual GLP-1 and GIP receptor agonist tirzepatide on gastric emptying was reported to be dose- and time-dependent, with the greatest effect observed after a single 5 mg dose but diminished after subsequent doses. When acetaminophen was administered following a single 5 mg dose of tirzepatide, acetaminophen peak plasma concentration (Cmax) was decreased by 50% and its median time to peak plasma concentration (Tmax) delayed by 1 hour. However, no significant impact on acetaminophen Cmax and Tmax was observed after 4 consecutive weekly doses of tirzepatide (5 mg/5 mg/8 mg/10 mg), and the overall exposure (AUC) of acetaminophen was unaffected. Tirzepatide at lower doses of 0.5 mg and 1.5 mg also had minimal effects on acetaminophen exposure.

MANAGEMENT: Although no specific dosage adjustment of concomitant medications is generally recommended based on available data, potential clinical impact on some oral medications cannot be ruled out, particularly those with a narrow therapeutic index or low bioavailability, those that depend on threshold concentrations for efficacy (e.g., antibiotics), and those that require rapid gastrointestinal absorption (e.g., hypnotics, analgesics). Pharmacologic response to concomitantly administered oral medications should be monitored more closely following initiation, dose adjustment, or discontinuation of a GLP-1 receptor agonist or a dual GLP-1 and GIP receptor agonist.

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.