A simple, sensitive high-performance liquid chromatography -ultraviolet method for the quantification of concentration and steady-state pharmacokinetics of itraconazole and hydroxyitraconazole.
BACKGROUND
A steady-state trough plasma itraconazole concentration greater than 500 ng/mL is a therapeutic target for itraconazole. A simple, rapid and sensitive high-performance liquid chromatography-based method was developed for quantitation of itraconazole and hydroxyitraconazole in human plasma.


METHODS
Itraconazole and hydroxyitraconazole were separated using a mobile phase of 0.5% KH2PO4 (pH 6.0)-acetonitrile (30:70, v/v) on a CAPCELLPAK C18 MGII column at a flow rate of 0.5 mL/min and ultraviolet absorbance at 260 nm.


RESULTS
The analysis required 200 microL of plasma and involved a rapid, simple solid-phase extraction with an Oasis HLB cartridge, which resulted in recoveries of 87-92% for itraconazole and 91-94% for hydroxyitraconazole. The lower limit of quantification for itraconazole and hydroxyitraconazole was 5 ng/mL each. Intra- and interday coefficients of variation for itraconazole and hydroxyitraconazole were less than 11.3% and 12.2%, respectively, and accuracies were within 11.7% and 4.5% over the linear range, respectively. Although the steady-state plasma concentrations of itraconazole and hydroxyitraconazole ranged from 506 to 2482 ng/mL and from 766 to 2444 ng/mL, respectively, after a two-day loading dose of 400 mg/day intravenous itraconazole followed by the administration of 200 mg/day itraconazole oral solution, calibration curves of itraconazole and hydroxyitraconazole showed positive linearity in a concentration range of 5-2500 and 50-2500 ng/mL, respectively.


CONCLUSIONS
Our results indicate that this method is applicable for the monitoring of plasma levels of itraconazole and hydroxyitraconazole in a clinical setting. Furthermore, the regimen presented here might also be effective in preventing infection, but further studies with large sample sizes are necessary to investigate this avenue.
Miura
M
M
Department of Pharmacy, Akita University Hospital, 1-1-1 Hondo, Akita 010-8543, Japan. m-miura@hos.akita-u.ac.jp
Takahashi
N
N
Nara
M
M
Fujishima
N
N
Kagaya
H
H
Kameoka
Y
Y
Saitoh
H
H
Tagawa
H
H
Sawada
K
K
D001774:Blood Chemical Analysis / Q000379:methods*; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004355:Drug Stability; D006801:Humans; D017964:Itraconazole / Q000031:analogs & derivatives* / Q000097:blood* / Q000302:isolation & purification / Q000493:pharmacokinetics*; D052616:Solid Phase Extraction; D014466:Ultraviolet Rays
C084794:hydroxyitraconazole; D017964:Itraconazole