A high-performance liquid chromatographic assay for the determination of itraconazole concentration using solid-phase extraction and small sample volume

Development, validation, and routine application of a high-performance liquid chromatography method coupled with a single mass detector for quantification of itraconazole, voriconazole, and posaconazole in human plasma

We have developed and validated a high-performance liquid chromatography method coupled with a mass detector to quantify itraconazole, voriconazole, and posaconazole using quinoxaline as the internal standard. The method involves protein precipitation with acetonitrile. Mean accuracy (percent deviation from the true value) and precision (relative standard deviation percentage) were less than 15%. Mean recovery was more than 80% for all drugs quantified. The lower limit of quantification was 0.031 microg/ml for itraconazole and posaconazole and 0.039 microg/ml for voriconazole. The calibration range tested was from 0.031 to 8 microg/ml for itraconazole and posaconazole and from 0.039 to 10 microg/ml for voriconazole.

A rapid HPLC method with fluorometric detection for determination of plasma itraconazole and hydroxy-itraconazole concentrations in cystic fibrosis children with allergic bronchopulmonary aspergillosis

The development and validation of a simple, rapid and selective high-performance liquid chromatography (HPLC) method is described for the quantitation of itraconazole and hydroxy-itraconazole in 100 microL of plasma from a paediatric population. The mobile phase of methanol (75% v/v) and water (25% v/v) was pumped at 1 mL/min through a C18 Symmetry (3.9 mm i.d. x 150 mm) cartridge. Using a protein-precipitation method, 100 microL internal standard (IS) solution (R051012, 555 microg/L in acetonitrile) were added to 100 microL of plasma followed by 10 microL zinc sulphate solution (20% w/v). Itraconazole, hydroxy-itraconazole and IS eluted at 4.7, 8.3 and 12.5 min, respectively and were detected fluorometrically at 250 nm (excitation) and 380 nm (emission). Recoveries were 87.1-96.7%. Calibrations in drug-free plasma were linear (r2 > 0.99) from 50 to 2000 microg/L, using 1/c2 (c = concentration) weighting. Intraday and interday imprecision (CV%) was 4.8-17.3 and 6.3-16.6% for itraconazole, and 4.6-17.9 and 7.02-18.4% for hydroxy-itraconazole. Inaccuracy was -7.1 to -14.7% for itraconazole and -0.1 to -9.7% for hydroxy-itraconazole. The clinical application of this method was demonstrated by measurement of itraconazole and hydroxy-itraconazole in plasma samples drawn from paediatric cystic fibrosis patients, who were prescribed itraconazole for treatment of allergic bronchopulmonary aspergillosis.

Clinical Pharmacokinetic Monitoring of Itraconazole Is Warranted in Only a Subset of Patients

Itraconazole is a synthetic triazole antifungal agent that is commonly used in the prophylaxis and treatment of fungal infection. A role for itraconazole drug monitoring has been suggested previously; however, the advent of new formulations and increased clinical evidence may aid in further defining this role. Consequently, we have used a previously published decision-making algorithm to determine whether clinical pharmacokinetic monitoring of itraconazole is warranted. First, itraconazole has proven efficacy for the prophylaxis and treatment of fungal infection in immunocompromised individuals such as neutropenic cancer, human immunodeficiency virus (HIV), and solid organ transplant patients. Several assays have been developed to quantify itraconazole and its main metabolite in patient plasma. Measurement of these plasma drug levels in many clinical studies has resulted in no clear definition of a relationship between concentration and efficacy. However, limited evidence suggests a correlation between itraconazole levels greater than 250 or 500 ng/mL and increased efficacy. Clinical monitoring of efficacy is difficult because of the challenges in diagnosis of fungal infections and nonspecific clinical symptoms associated with fungal infections. Pharmacokinetic studies of itraconazole indicate that significant inter- and intrapatient variability exists in both healthy and immunocompromised patient populations, although subpopulations such as neutropenic cancer and HIV patients appear to require more drug than their healthy counterparts to attain similar drug levels. A therapeutic range has not been defined for itraconazole, but because of its relatively minimal side effects, a narrow range is unlikely. Drug interactions can occur with itraconazole because it is both an inhibitor and substrate of the cytochrome P450 3A4 (CYP3A4) enzyme and P-glycoprotein transporter systems. Protein binding alterations could also lead to differences in drug effect. Last, the duration of treatment of prophylaxis is significantly long to propose a potential benefit from drug monitoring. From weighing the available evidence, it appears that itraconazole drug level monitoring would provide more information on efficacy than clinical judgment alone in a subset of patients. Immunosuppressed patients requiring preventative therapy who have suspected poor absorption, are on concomitant enzyme inducers, or are suspected to be noncompliant would have the greatest benefit from itraconazole drug monitoring.

Studies on itraconazole delivery and pharmacokinetics in mallard ducks (Anas platyrhynchos)

Avian aspergillosis is commonly treated with itraconazole (ITZ). This paper describes two studies using mallard ducks (Anas platyrhynchos). The first study evaluated in vivo release of ITZ from subcutaneously injected controlled-release gel formulations and the second study compared pharmacokinetic parameters for two ITZ oral suspensions. ITZ-A suspension was prepared by mixing contents of commercially available capsules with hydrochloric acid and orange juice. ITZ-B suspension was prepared by dispersing the complex of the drug with hydroxypropyl-beta-cyclodextrin in water. Concentrations of ITZ and its active metabolite, hydroxyitraconazole (OH-ITZ), in plasma and tissue samples were measured using high-performance liquid chromatography. In the second study, drug concentrations in plasma samples were also analyzed using a bioassay. After administration of two ITZ controlled-release formulations, plasma and tissue concentrations of ITZ and OH-ITZ were either very low (< or = 52 ng/mL) or undetectable. Exceptions included skin, subcutaneous fat, and muscle adjacent to the injection site. The drug from ITZ-A and ITZ-B suspensions was absorbed after oral administration. ITZ pharmacokinetic parameters for both suspensions in mallard ducks were similar and the bioassay successfully measured ITZ equivalents in plasma samples from ducks.

Reduced oral itraconazole bioavailability by antacid suspension

AIMS

To investigate the effects of antacid suspension on oral absorption of itraconazole.

METHODS

A randomized, open-labelled, two-period, crossover study with a 1-week washout period was conducted in 12 healthy Thai male volunteers. The participants were allocated in either treatment A or B in the first period. In treatment A, the volunteers were orally administered with 200 mg of itraconazole alone. In treatment B, the volunteers were administered orally with 200 mg of itraconazole co-administered with antacid suspension. Serial serum samples were collected over the period of 24 h and subsequently analysed by using a validated high-pressure liquid chromatographic method with ultraviolet detection. Pharmacokinetic parameters were determined by non-compartmental analysis.

RESULTS

Time to reach maximal concentration (Tmax), maximal concentration (Cmax) and area under the curve (AUC0-infinity) were markedly decreased in antacid-treated group. Tmax for treatment A was 3.0 +/- 0.4 and 5.1 +/- 2.7 h for treatment B. Cmax and AUC0-infinity of treatments A and B were 146.3 +/- 70.5 vs. 43.6 +/- 16.9 (ng/mL) and 1928.5 +/- 1114.6 vs. 654.8 +/- 452.2 (ng x h/mL) respectively. 90% Confidence interval (90% CI) of Cmax and AUC0--infinity were 24.1-42.1 and 16.2-65.9 respectively.

CONCLUSIONS

Rate and extent of itraconazole oral absorption were markedly decreased by concurrent use of antacid suspension. Hence, co-administration of itraconazole and antacid suspension should be avoided.

Liquid chromatographic method for the determination of plasma itraconazole and its hydroxy metabolite in pharmacokinetic/bioavailability studies

A sensitive and selective high-performance liquid chromatographic method was developed for the determination of itraconazole and its active metabolite, hydroxyitraconazole, in human plasma. Prior to analysis, both compounds together with the internal standard were extracted from alkalinized plasma samples using a 3:2 (v/v) mixture of 2,2,4-trimethylpentane and dichloromethane. The mobile phase comprised 0.02 M potassium dihydrogen phosphate-acetonitrile (1:1, v/v) adjusted to pH 3.0. Analysis was run at flow-rate of 0.9 ml/min with excitation and emission wavelengths set at 260 and 365 nm, respectively. Itraconazole was found to adsorb on glass or plastic tubes, but could be circumvented by prior treating the tubes using 10% dichlorodimethylsilane in toluene. Moreover, rinsing the injector port with acetonitrile helped to overcome any carry-over effect. This problem was not encountered with hydroxyitraconazole. The method was sensitive with limit of quantification of 3 ng/ml for itraconazole and 6 ng/ml for hydroxyitraconazole. The calibration curve was linear over a concentration range of 2.8-720 ng/ml for itraconazole and 5.6-720 ng/ml for the hydroxy metabolite. Mean recovery value of the extraction procedure for both compounds was about 85%, while the within-day and between-day coefficient of variation and percent error values of the assay method were all less than 15%. Hence, the method is suitable for use in pharmacokinetic and bioavailability studies of itraconazole.

Determination of itraconazole and hydroxyitraconazole in human serum and plasma by micellar electrokinetic chromatography

The electrokinetic separation of the hydrophobic antimycotic drug itraconazole (ITC) and its major metabolite, hydroxyitraconazole (HITC), by a binary aqueous-organic solvent medium containing sodium dodecylsulfate, by microemulsion electrokinetic chromatography (MEEKC) and by micellar electrokinetic chromatography (MEKC) was studied. The results suggest that the first approach is difficult to apply and that there is no substantial difference between separations performed using MEEKC and MEKC modified with n-butanol. The simpler MEKC method is more than adequate and was thus employed for the analysis of ITC and HITC in human serum and plasma. Separation was achieved in plain fused-silica capillaries having a low-pH buffer (pH 2.2) with sodium dodecyl sulfate micelles and reversed polarity. The addition of 2-propanol and n-butanol enhanced analyte solubility and altered the selectivity of the separation by influencing the magnitude of the electrophoretic component in the separation mechanism. Under optimised conditions and using head-column field-amplified sample stacking, an internal standard, ITC and two forms of HITC could be separated in under 9 min, with detection limits less than 0.01 microg/mL. Analysis of samples from patients currently prescribed ITC revealed a different HITC peak area ratio to that of the standards, suggesting a stereoselective component of ITC metabolisation. Comparison of MEKC data with those of a HPLC method employed on a routine basis showed excellent agreement, indicating the potential of this approach for therapeutic drug monitoring of ITC.

Determination of itraconazole and hydroxyitraconazole in plasma by use of liquid chromatography-tandem mass spectrometry with on-line solid-phase extraction

In this paper a method for the simultaneous quantification of the anti-fungal drug itraconazole and its co-active metabolite hydroxyitraconazole in plasma employing liquid chromatography tandem-mass spectrometry and automated solid-phase extraction is described. The method proved rugged, enables short turn-around times and is highly specific. Since there is growing evidence for the importance of therapeutic drug monitoring of itraconazole in the prophylaxis and treatment of invasive fungal infections, the method described here is of interest for a large number of tertiary care hospital laboratories.

Application of capillary zone electrophoresis with off-line solid-phase extraction to in vitro metabolism studies of antifungals

A simple and robust solid-phase extraction (SPE) procedure for the cleanup and sample preconcentration of antifungals (ketoconazole, clotrimazole, itraconazole, fluconazole, and voriconazole) and their metabolites after incubation with human liver microsomes, as well as a simplified capillary zone electrophoresis (CZE) method for their rapid analysis, have been developed to determine the stability of these compounds in in vitro samples. Three different sample pretreatment procedures using SPE with reversed-phase sorbents (100 mg C8, 100 mg C18, and 30 mg Oasis-HLB) were studied. The highest and most reproducible recoveries were obtained using a 30 mg Oasis-HLB sorbent and methanol containing 2% acetic acid as eluent. Enrichment by a factor of about four times was achieved by reconstituting the final SPE eluates to a small volume. For the CZE separation, good separations without interfering peaks due to the in vitro matrix were obtained with a simple running electrolyte using a fused-silica capillary. The best separation for all components originated by each tested drug after incubation with human liver microsomes (unmetabolized parent drug and its metabolites) was obtained using a 0.05 M phosphate running buffer (pH 2.2) without additives. The effect of the injection volume was also investigated in order to obtain the best sensitivity. Performance levels in terms of precision, linearity, limits of detection, and robustness were determined.

Expedient microdetermination of itraconazole and hydroxyitraconazole in plasma by high-performance liquid chromatography with fluorescence detection

The authors describe a useful and rapid micromethod for the analysis of itraconazole (ITZ) and its active metabolite hydroxyitraconazole (HIT) in human plasma. After a simple deproteinization of 100 microL plasma with acetonitrile, the drug, its metabolite, and an internal standard (IS, ketoconazole) were separated on an 8 mm x 10 cm NovaPak (Waters Associates; Milford, MA) C(18) 4-microm particle-size radial compression cartridge. The compounds of interest were detected using a fluorescence detector with the excitation wavelength set at 260 nm and the emission at 365 nm. The mobile phase consisted of 420 mL water adjusted to a pH of 2.5 with phosphoric acid, 580 mL acetonitrile, and 100 microL triethylamine, which was delivered at a flow rate of 3.0 mL/min. This expedient and rugged method is being used to monitor therapeutic levels in bone marrow transplant recipients who are taking the drug for prophylaxis.

Optimization of the separation of a group of antifungals by capillary zone electrophoresis

Two simple, rapid, and efficient methods for the analysis of seven antifungal compounds have been developed by capillary zone electrophoresis. Resolutions higher than 1.5 were obtained using 0.025 M phosphate buffer (pH 2.30) (analysis time close to 9 min) or 0.2 M formic acid (pH 2.15) (analysis time close to 6 min), with an applied voltage of 20 kV and a temperature of 30 degrees C. The highest sensitivity and selectivity can be obtained using phosphate buffer but the shortest analysis times are achieved in the formic system. The analytical characteristics of the optimized methods were investigated. The reproducibility obtained for migration times (RSD(n = 10) < or = 1.0%) and peak areas (RSD(n = 10) < or = 4.3%) was acceptable, but better reproducibilities were obtained when verapamil was used as internal standard (RSD(n = 10) < 0.4% for relative migration times and RSD(n = 10) < or = 2.2% for peak area ratios). The lowest limit of detection was obtained for clotrimazole (0.12 microg/ml) and the highest for fluconazole and voriconazole (0.90 microg/ml). The lowest and the highest limits of quantitation were, respectively, 0.40 microg/ml for clotrimazole and 3.00 microg/ml for fluconazole and voriconazole.

Rapid and sensitive high performance liquid chromatographic method for the determination of itraconazole and its hydroxy-metabolite in human serum

Published high performance liquid chromatographic (HPLC) methods for the determination of itraconazole (ITZ) in biological matrices are labor intensive, extraction-based procedures which operate at a pH approaching the limit of column tolerance, and unless modified, cannot measure its hydroxy-metabolite (OH-ITZ). A protein precipitation-based method requiring no solvent extraction and utilizing a base-deactivated C18 analytical column to minimize peak tailing is described herein. Calibration curves for OH-ITZ and ITZ were linear from 25-1500 ng ml-1 (r2 > or = 0.999). Intra-assay relative standard deviations (R.S.D.) were below 12%. Inter-assay R.S.D. were below 14%. This method provides a rapid means for the accurate and precise determination of both OH-ITZ and ITZ concentrations in human serum.