Methadone-Drug Interactions (Medications, illicit drugs, & other substances)

Each year in the U.S. there are innumerable adverse drug reactions, broadly defined as any unexpected, unintended, undesired, or excessive response to a medicine. Such reactions may require discontinuing or changing medication therapy. Furthermore, greater than 2 million of those are serious reactions resulting in hospitalization and/or permanent disability, and there are more than 100,000 deaths annually attributed to reactions involving prescribed medications (Cohen 1999; Wilkinson 2005). Three-fourths of those adverse reactions relate to drug interactions, which occur when the amount or action of a drug in the body is altered – usually increased or decreased – by the presence of another drug or multiple drugs (Bochner 2000; Levy et al. 2000; Piscitelli and Rodvold 2001). Avoiding these can be difficult, since the number of potential interactions among diverse drugs used in clinical practice can be overwhelming; more than 2,000 such interactions have been described in the literature and new cases appear monthly (Levy et al. 2000). As the tables in this document indicate, there are more than 100 substances – medications, illicit drugs, OTC products, etc. – that can interact in some fashion to affect a patient’s response to methadone.