Decreased responsiveness to oxycodone: A case of a pharmacokinetic drug interaction?

2015/07/01 by Doreen Pon, PharmD Candidate Joon Hwang, PharmD Candidate Teresa Lo +1 · 1 citation
Medicine · #Opioid Use Disorder Treatment #Pain Management and Opioid Use #Pharmaceutical Practices and Patient Outcomes

paper · doi:10.5055/jom.2015.0284

openalex publication_date 2015/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11

Abstract

Concurrent administration of oxycodone and phenytoin may cause, through induction of CYP3A4 enzymes, decreased analgesic effects of oxycodone. However, no descriptions of this interaction exist. A patient who was on oxycodone for chronic back pain was admitted to the hospital. Five days after initiating fosphenytoin, the patient experienced a dramatic escalation in his pain and lack of response to oxycodone breakthrough doses. Changing oxycodone to hydromorphone resulted in significantly improved analgesia. Concurrent use of fosphenytoin and oxycodone may increase the conversion of oxycodone to inactive metabolites, resulting in decreased analgesia. This may be avoided using hydromorphone, morphine, or oxymorphone.

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