Levomethadone; Methadone/Fluconazole; Voriconazole Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

Fluconazole and voriconazole may slow down how quickly your liver processes your methadone.

What might happen:

The amount of methadone in your blood may increase. This may cause you to have slowed breathing or an irregular heartbeat, which may be life-threatening.High serotonin levels may cause changes in body temperature, blood pressure, and behavior or mood, leading to a medical condition called Serotonin Syndrome. Serotonin Syndrome may be life threatening.

What you should do about this interaction:

Contact your healthcare professionals (e.g doctor or pharmacist) about taking these medicines together. Let your doctor know right away if you notice an irregular heartbeat or have any breathing problems, dizziness or fainting episodes.Ask your doctor or pharmacist if you should have naloxone available to treat opioid overdose. Teach your family or household members about the signs of an opioid overdose and how to treat it. If someone has overdosed and has serious symptoms such as passing out or trouble breathing, give them naloxone if available, then call 911. If the person is awake and has no symptoms, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: slow/shallow breathing, slow heartbeat, coma.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

  • 1.Vfend (voriconazole) US prescribing information. Pfizer Inc. January, 2019.
  • 2.Diflucan (fluconazole) US prescribing information. Pfizer Inc. February, 2019.
  • 3.Dolophine (methadone hydrochloride) US prescribing information. Wast-Ward Pharmaceuticals Corp. October, 2019.
  • 4.Levopidon (levomethadone) Swedish Summary of Product Characteristics. DNE Pharma AS November 30, 2018.
  • 5.Drew BJ, Ackerman MJ, Funk M, Gibler WB, Kligfield P, Menon V, Philippides GJ, Roden DM, Zareba W. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. J Am Coll Cardiol 2010 Mar 2;55(9):934-47.
  • 6.USFood and Drug Administration. FDA Drug Safety Communication: FDA recommends health care professionals discuss naloxone with all patients when prescribing opioid pain relievers or medicines to treat opioid use disorder. Available at: https://www.fda.gov/drugs/drug-safety-and-availability/fda-recommends-heal th-care-professionals-discuss-naloxone-all-patients-when-prescribing-opioi d-pain July 23, 2020.
  • 7.Phansalkar S, Desai AA, Bell D, Yoshida E, Doole J, Czochanski M, Middleton B, Bates DW. High-priority drug-drug interactions for use in electronic health records. J Am Med Inform Assoc 2012 Sep-Oct; 19(5):735-43.

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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.