Voriconazole drastically increases exposure to oral oxycodone.

Author(s): Hagelberg NM, Nieminen TH, Saari TI, Neuvonen M, Neuvonen PJ, Laine K, Olkkola KT

Affiliation(s): Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital, PO Box 52 (Kiinamyllynkatu 4-8), FI-20521 Turku, Finland.

Publication date & source: 2009-03, Eur J Clin Pharmacol., 65(3):263-71. Epub 2008 Oct 3.

Publication type: Randomized Controlled Trial; Research Support, Non-U.S. Gov't

OBJECTIVE: We investigated the effect of voriconazole on the pharmacokinetics and pharmacodynamics of oxycodone. METHODS: Twelve healthy subjects ingested either voriconazole or placebo for 4 days in a randomized, cross-over study. On day 3, they ingested 10 mg oxycodone. Timed plasma samples were collected for the measurement of oxycodone, noroxycodone, oxymorphone, noroxymorphone and voriconazole up to 48 h, and pharmacodynamic effects were recorded. RESULTS: When voriconazole was taken at the same time as oxycodone, the mean area under the plasma concentration-time curve (AUC(0-infinity)) of oxycodone increased 3.6-fold (range 2.7- to 5.6-fold), peak plasma concentration 1.7-fold and elimination half-life 2.0-fold (p < 0.001) when compared to placebo. The AUC(0-infinity) ratio of noroxycodone to oxycodone was decreased by 92% (p < 0.001), and that of oxymorphone increased by 108% (p < 0.01). Pharmacodynamic effects of oxycodone were modestly increased by voriconazole. CONCLUSIONS: Voriconazole inhibits the CYP3A-mediated N-demethylation of oxycodone, drastically increasing exposure to oral oxycodone. Clinically, lower doses of oxycodone may be needed during voriconazole treatment to avoid opioid-related adverse effects especially after repeated dosing.