title: Decreased responsiveness to oxycodone: A case of a pharmacokinetic drug interaction?
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.
authors: Assistant Professor, Department of Pharmacy Practice and Administration, College of Pharmacy, Western University of Health Sciences, Pomona, California; Faculty in Residence, Department of Pharmacy, City of Hope National Medical Center, Duarte, California.
authors: Doreen
authors: D
authors: Pon
authors: College of Pharmacy, Western University of Health Sciences, Pomona, California.
authors: Joon
authors: J
authors: Hwang
authors: College of Pharmacy, Western University of Health Sciences, Pomona, California.
authors: Teresa
authors: T
authors: Lo
authors: Assistant Clinical Professor, Department of Supportive Care Medicine, City of Hope National Medical Center, Duarte, California.
authors: Carin Van
authors: CV
authors: Zyl
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000493:pharmacokinetics; D059350:Chronic Pain / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*; D065694:Cytochrome P-450 CYP1A2 Inducers / Q000008:administration & dosage / Q000493:pharmacokinetics; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D057915:Drug Substitution / Q000379:methods; D006801:Humans; D004091:Hydromorphone / Q000008:administration & dosage / Q000493:pharmacokinetics; D008297:Male; D010098:Oxycodone / Q000008:administration & dosage / Q000493:pharmacokinetics; D059408:Pain Management / Q000379:methods; D010147:Pain Measurement; D010672:Phenytoin / Q000008:administration & dosage / Q000493:pharmacokinetics; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000150:complications; D012640:Seizures / Q000150:complications / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D065694:Cytochrome P-450 CYP1A2 Inducers; D010672:Phenytoin; D010098:Oxycodone; D051544:Cytochrome P-450 CYP3A; D004091:Hydromorphone