Effects of itraconazole on the pharmacokinetics and pharmacodynamics of intravenously and orally administered oxycodone.
BACKGROUND
The aim of this study was to investigate the effects of the cytochrome P450 3A4 (CYP34A) inhibitor itraconazole on the pharmacokinetics and pharmacodynamics of orally and intravenously administered oxycodone.


METHODS
Twelve healthy subjects were administered 200 mg itraconazole or placebo orally for 5 days in a four-session paired cross-over study. On day 4, oxycodone was administered intravenously (0.1 mg/kg) in the first part of the study and orally (10 mg) in the second part. Plasma concentrations of oxycodone and its oxidative metabolites were measured for 48 h, and pharmacodynamic effects were evaluated.


RESULTS
Itraconazole decreased plasma clearance (Cl) and increased the area under the plasma concentration-time curve (AUC0-infinity) of intravenous oxycodone by 32 and 51%, respectively (P<0.001) and increased the AUC(0-infinity) of orally administrated oxycodone by 144% (P<0.001). Most of the pharmacokinetic changes in oral oxycodone were seen in the elimination phase, with modest effects by itraconazole on its peak concentration, which was increased by 45% (P=0.009). The AUC(0-48) of noroxycodone was decreased by 49% (P<0.001) and that of oxymorphone was increased by 359% (P<0.001) after the administration of oral oxycodone. The pharmacologic effects of oxycodone were enhanced by itraconazole only modestly.


CONCLUSIONS
Itraconazole increased the exposure to oxycodone by inhibiting its CYP3A4-mediated N-demethylation. The clinical use of itraconazole in patients receiving multiple doses of oxycodone for pain relief may increase the risk of opioid-associated adverse effects.
Saari
Teijo I
TI
Department of Anesthesiology, University of Turku, Finland. teijo.saari@tyks.fi
Grönlund
Juha
J
Hagelberg
Nora M
NM
Neuvonen
Mikko
M
Laine
Kari
K
Neuvonen
Pertti J
PJ
Olkkola
Klaus T
KT
D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology*; D019540:Area Under Curve; D018592:Cross-Over Studies; D051544:Cytochrome P-450 CYP3A; D065692:Cytochrome P-450 CYP3A Inhibitors; D006801:Humans; D007275:Injections, Intravenous; D017964:Itraconazole / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D009019:Morphinans / Q000493:pharmacokinetics / Q000494:pharmacology; D010084:Oxidation-Reduction; D010098:Oxycodone / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology*; D010111:Oxymorphone / Q000493:pharmacokinetics / Q000494:pharmacology
D000701:Analgesics, Opioid; D065692:Cytochrome P-450 CYP3A Inhibitors; D009019:Morphinans; D017964:Itraconazole; C077256:noroxycodone; D010111:Oxymorphone; D010098:Oxycodone; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human