Pharmacokinetics Of Itraconazole Research Articles

The effects of formulation on the pharmacokinetics of itraconazole and amiodarone in dogs after oral administration of a combination product, commercial products, and compounded products.

This study evaluated four different formulations of itraconazole and amiodarone. Formulation 1 was Vida's combination tablet containing both active pharmaceutical ingredients (APIs). Formulation 2 was separate, commercially available human generic capsules and tablets of itraconazole and amiodarone, respectively. Formulation 3 was separate, compounded suspensions of itraconazole and amiodarone. Formulation 4 was a compounded chewable tablet of itraconazole. Eight female dogs were dosed with 5 mg/kg of itraconazole and 15 mg/kg amiodarone (except for formulation 4, which only received 5 mg/kg itraconazole) once weekly for 4 weeks using a modified Latin Square design, ensuring that all dogs received all formulations with a 7-day washout between treatments. Animals were fasted overnight prior to each dose administration, with food returned to all animals 4 h post-dose. Blood samples (3 mL) were collected pre-treatment (0) and at appropriate time points over 72 h after each dose for a total of 14 samples per dog per treatment. There was high variability in the serum concentration data within treatment groups for itraconazole. The compounded suspensions were difficult to dose due to the nature of the formulations. The volumes dosed were accurate and consistent, but the suspension was thin and settled immediately when shaking was stopped for both itraconazole and amiodarone. All serum samples following itraconazole chewable tablet administration were not detectable or just above itraconazole's LOQ and thus did not allow for pharmacokinetic determination.

Prediction of gastric pH-mediated drug exposure using physiologically-based pharmacokinetic modeling: A case study of itraconazole.

Abnormal gastric acidity, including achlorhydria, can act as a significant source of variability in orally administered drugs especially with pH-sensitive solubility profiles, such as weak bases, potentially resulting in an undesirable therapeutic response. This study aimed to evaluate the utility of physiologically-based pharmacokinetic (PBPK) modeling in the prediction of gastric pH-mediated drug exposure by using itraconazole, a weak base, as a case. An itraconazole PBPK model was developed on the mechanistic basis of its absorption kinetics in a middle-out manner from a stepwise in vitro-in vivo extrapolation to in vivo refinement. Afterward, an independent prospective clinical study evaluating gastric pH and itraconazole pharmacokinetics (PKs) under normal gastric acidity and esomeprazole-induced gastric hypoacidity was conducted for model validation. Validation was performed by comparing the predicted data with the clinical observations, and the valid model was subsequently applied to predict PK changes under achlorhydria. The developed itraconazole PBPK model showed reasonable reproducibility for gastric pH-mediated exposure observed in the clinical investigation. Based on the model-based simulations, itraconazole exposure was expected to be decreased up to 65% under achlorhydria, and furthermore, gastric pH-mediated exposure could be mechanistically interpreted according to sequential variation in total solubility, dissolution, and absorption. This study suggested the utility of PBPK modeling in the prediction of gastric pH-mediated exposure, especially for drugs whose absorption is susceptible to gastric pH. Our findings will serve as a leading model for further mechanistic assessment of exposure depending on gastric pH for various drugs, ultimately contributing to personalized pharmacotherapy.

Evaluation of the inhibitory effects of itraconazole on letermovir.

Letermovir, a cytomegalovirus (CMV) DNA terminase complex inhibitor, is a substrate of ABCB1 (P-glycoprotein; P-gp), organic anion transporting polypeptide (OATP)1B1/3, UDP-glucuronosyltransferase (UGT)1A1, UGT1A3 and possibly ABCG2 (breast cancer resistance protein; BCRP). A study was conducted to evaluate the effects of itraconazole, a prototypic ABCB1/ABCG2 inhibitor, on letermovir pharmacokinetics (PK) and the effects of letermovir on itraconazole PK. In an open-label, fixed-sequence study in 14 healthy participants, 200 mg oral itraconazole was administered once daily for 4 days. Following a 10-day washout, 480 mg oral letermovir was administered once daily for 14 days (Days 1-14) and then coadministered with 200 mg itraconazole once daily for 4 days (Days 15-18). Intensive PK sampling was performed for letermovir and itraconazole. PK and safety were evaluated. Letermovir geometric mean ratio (GMR; 90% confidence interval [CI]) for area under the concentration-time curve from time 0 to 24 h (AUC0-24 ) was 1.33 (1.17, 1.51) and for maximum concentration (Cmax ) was 1.21 (1.05, 1.39) following administration with/without itraconazole. Itraconazole GMR (90% CI) for AUC0-24 was 0.76 (0.71, 0.81) and for Cmax was 0.84 (0.76, 0.92) following administration with/without letermovir. Coadministration of letermovir with itraconazole was generally well tolerated. The increase in letermovir exposure with coadministration of itraconazole is likely predominantly due to inhibition of intestinal ABCB1 and potentially ABCG2 transport. The mechanism for the decrease in itraconazole exposure is unknown. The modest changes in letermovir and itraconazole PK are not considered clinically meaningful.

Influence of Gender, Body Mass Index, and Age on the Pharmacokinetics of Itraconazole in Healthy Subjects: Non-Compartmental Versus Compartmental Analysis.

Itraconazole is a triazole antifungal agent with highly variable pharmacokinetics, with not yet fully identified factors as the source of this variability. Our study aimed to examine the influence of body mass index, gender, and age on the first dose pharmacokinetics of itraconazole in healthy subjects, using pharmacokinetic modeling, non-compartmental versus compartmental ones. A total of 114 itraconazole and hydroxy-itraconazole sets of plasma concentrations of healthy subjects of both genders, determined using a validated liquid chromatographic method with mass spectrometric detection (LC-MS), were obtained for pharmacokinetic analyses performed by the computer program Kinetica 5®. Genetic polymorphism in CYP3A4, CYP3A5, CYP1A1, CYP2C9, and CYP2C19 was analyzed using PCR-based methods. Multiple linear regression analysis indicated that gender had a significant effect on AUC as the most important pharmacokinetics endpoint, whereas body mass index and age did not show such an influence. Therefore, further analysis considered gender and indicated that both geometric mean values of itraconazole and hydroxy-itraconazole plasma concentrations in men were prominently higher than those in women. A significant reduction of the geometric mean values of Cmax and AUC and increment of Vd in females compared with males were obtained. Analyzed genotypes and gender differences in drug pharmacokinetics could not be related. Non-compartmental and one-compartmental models complemented each other, whereas the application of the two-compartmental model showed a significant correlation with the analysis of one compartment. They indicated a significant influence of gender on itraconazole pharmacokinetics after administration of the single oral dose of the drug, given under fed conditions. Women were less exposed to itraconazole and hydroxy-itraconazole than men due to poorer absorption of itraconazole, its more intense pre-systemic metabolism, and higher distribution of both drug and its metabolite.

Koncentracije itrakonazola i hidroksi-itrakonazola nakon oralne primene leka kod zdravih ljudi - uticaj pola

Introduction: Itraconazole is an antifungal drug belonging to the triazole group. After oral application, it is rapidly absorbed, but its bioavailability is reduced due to an intensive first-pass through the liver metabolism effect. A large number of metabolites (the most important of which is hydroxyitraconazole) are produced by isoform CYP3A4 of cytochrome P450. The variability of itraconazole pharmacokinetics is the result of numerous factors that have not yet been fully clarified. Our study aimed to investigate the influence of gender on itraconazole and hydroxyitraconazole plasma concentrations in healthy adults after an oral application of a single dose of itraconazole. Methods: Pharmacokinetic analysis was performed after oral administration of itraconazole in a single dose of 100 mg to 22 male and 16 female healthy volunteers. Blood samples were collected before taking the drug and at appropriate time intervals up to 72 hours later. Itraconazole and hydroxyitraconazole concentrations were determined using a validated liquid chromatography method with mass spectrometric detection (LC-MS/MS) and their pharmacokinetic parameters were calculated by using the Kinetica programme, version 5.0: Cmax, Tmax, PIK (0-72), PIK (0-∞), T1/2, and Ke. Results: The median values of both itraconazole and hydroxyitraconazole were lower in women in comparison to men during the whole period of observation. Moreover, median values of Cmax, PIK(0-72) and PIK(0-∞) parameters were also significantly lower in women, concerning both itraconazole (p=0.005, 0.036 and 0.036, respectively) and its metabolite (p=0.004, 0.010 and 0.044, respectively). Elimination parameters - T1/2 and Ke did not differ between genders. Conclusion: Women were less exposed to itraconazole and its active metabolite than men following an oral application of the drug, possibly as a result of lower bioavailability due to a more intense pre-systemic metabolism, as a result of a higher expression and/or activity of the isoform enzyme, which metabolises itraconazole, and which would need to be confirmed by pharmacogenomic analysis.

Itraconazole Dosing and Drug Monitoring at a Tertiary Children's Hospital.

Itraconazole is a broad-spectrum antifungal agent used for prophylaxis and treatment of fungal infections in immunocompromised children. Achieving the recommended target serum itraconazole trough concentration of ≥0.5 mg/L is challenging in children because of variation in itraconazole pharmacokinetics with age. We studied itraconazole use and treatment outcomes in a tertiary children's hospital. We did a 10-year retrospective review of medical records of children at the Royal Children's Hospital Melbourne who received oral itraconazole and had therapeutic drug monitoring (TDM). Overall, 81 children received 92 courses of oral itraconazole and had TDM. Of 222 TDM samples, 183 (82.4%) were taken at the appropriate time (trough level at steady state). Patients ≤12 and >12 years of age required median doses of 6.2 and 3.9 mg/kg/d, respectively, to attain target trough levels (P < 0.001). Of children ≤12 years of age, 71.4% required doses above the recommended dose of 5 mg/kg/d to achieve therapeutic levels, compared with 17.4% of those >12 years of age. At least 1 subtherapeutic trough concentration was reported in 63 (76.8%) courses; in only 18 (28.6%) of these was the dose adjusted. Gastrointestinal symptoms [14/92 (15.2%) courses] and hepatotoxicity [6/92 (6.5%)] were the most frequent adverse events. Neither was associated with elevated trough levels. The poor attainment of target levels with current recommended dosing in children <12 years of age suggests that higher empiric doses are needed in this age group. The poor compliance with TDM guidelines highlights the need for better education about appropriate timing of sampling and dose adjustment.

A PHASE 1/1B STUDY OF AN INHALED FORMULATION OF ITRACONAZOLE IN HEALTHY VOLUNTEERS AND ASTHMATICS

Introduction Oral itraconazole has variable pharmacokinetics and risks of significant adverse events (AEs) associated with high plasma exposure. A dry powder inhalation formulation of itraconazole (ITRA) is being developed to treat Allergic Bronchopulmonary Aspergillosis (ABPA). This study was conducted to evaluate safety, tolerability and pharmacokinetics of ITRA in healthy volunteers and asthmatics. Methods The study was a 3-part, multi-center, open-label study. Healthy volunteers (n=5-6/cohort) received either single (Part 1 - 5mg, 10mg, 25mg, 35mg) or multiple doses of ITRA (Part 2 -10mg, 20mg, 35mg) over 14d. In Part 3 stable, adult asthmatics received a single dose of 20mg ITRA or 200mg of oral itraconazole in a 2-period cross-over design. Itraconazole plasma (Parts 1-3) and sputum (Part 3) concentrations were evaluated. Results All study drug-related AEs were mild, and no moderate, severe or serious study drug-related AEs were reported. The most common drug-related AE was the infrequent occurrence of mild cough. At steady-state, ITRA resulted in plasma exposure (AUC0-24h) that was 100-400 fold lower across doses tested than reported for oral itraconazole. In asthmatics, ITRA achieved Cmax sputum concentrations 45-fold higher and plasma AUC0-24h concentrations 85-fold lower than oral itraconazole. Conclusions ITRA was safe and well-tolerated under the study conditions tested, and achieved significantly higher lung and lower plasma exposure compared to oral itraconazole, supporting the potential of ITRA to improve upon both the efficacy and safety profile observed with oral itraconazole in patients with ABPA.

Mechanistic Assessment of the Effect of Omeprazole on the In Vivo Pharmacokinetics of Itraconazole in Healthy Volunteers.

SUBA-itraconazole and Sporanox are two oral formulations of itraconazole. Drug-drug interactions with omeprazole have been previously reported; however, mechanistic understanding of the pharmacological and physiological interactions of omeprazole with orally administered itraconazole within a population modeling paradigm is lacking. The objective of this analysis was to mechanistically describe and quantify the effect of omeprazole on the pharmacokinetics of itraconazole and its major metabolite, hydroxyitraconazole from the SUBA itraconazole and Sporanox formulations. An in vitro-in vivo (IVIV) pharmacokinetic model of itraconazole and hydroxyitraconazole was developed including data from an omeprazole interaction study with SUBA itraconazole. Meta-models of gastric pH for healthy subjects and subjects receiving omeprazole were integrated into the IVIV model to capture omeprazole-mediated gastric pH changes on itraconazole dissolution and absorption. Omeprazole influenced the kinetics of itraconazole through altering the dissolution and absorption due to the pH-dependent solubility of itraconazole, inhibition of efflux transporters, and inhibiting the metabolism of itraconazole and hydroxyitraconazole. The model-predicted population effects of omeprazole on itraconazole from SUBA-itraconazole were to increase the area under the concentration-time curve (AUC0-24) and maximum concentration (Cmax) by 35 and 31%, respectively, and to decrease AUC0-24 and Cmax from Sporanox by 68 and 76%, respectively. Unlike SUBA itraconazole, which requires basic pH for itraconazole release, the omeprazole-induced pH-mediated reduction in Sporanox dissolution overrides any increased exposure from the drug-drug interaction at hepatic metabolizing enzymes or efflux transporters. The model presented here is the most complete quantitative description of the pharmacokinetics of itraconazole and hydroxyitraconazole currently available.

Pharmacokinetic evaluation of oral itraconazole for antifungal prophylaxis in children.

Itraconazole is a first-generation triazole agent with an extended spectrum of activity; it is licensed in adults for superficial and systemic fungal infections; no recommendation has been yet established for use in children patients. Its variable and unpredictable oral bioavailability make it difficult to determine the optimal dosing regimen. Hence, therapeutic drug monitoring, highly available in clinical practice, may improve itraconazole treatment success and safety. The aim of the study was to describe in paediatrics the oral itraconazole pharmacokinetics, used for prophylaxis. Moreover, we evaluated the utility of its therapeutic drug monitoring in this cohort. A fully validated chromatographic method was used to quantify itraconazole concentration in plasma collected from paediatric patients, at the end of dosing interval. Associations between variables were tested using the Pearson test. Mann-Whitney U test has been used to probe the influence of categorical variables on continuous ones. Any predictive power of the considered variables was finally evaluated through univariate and multivariate linear and logistic regression analyses. A high inter-individual variability was shown; ethnicity (beta coefficient, β -0.161 and interval of confidence at 95%, IC -395.035; -62.383) and gender (β 0.123 and IC 9.590; 349.395) remained in the final linear regression model with P value of .007 and .038, respectively. This study highlights that therapeutic drug monitoring is required to achieve an adequate target itraconazole serum exposure.

High payload itraconazole-incorporated lipid nanoparticles with modulated release property for oral and parenteral administration.

The aim of this study was to develop high payload itraconazole-incorporated lipid nanoparticles (HINP) with modulated release property using a binary mixture core of solid and liquid lipid for oral and parenteral administration. High payload itraconazole-incorporated lipid nanoparticles were prepared by hot high-pressure homogenization method using tristearin (TS) as a solid lipid, triolein (TO) as a liquid lipid and egg phosphatidylcholine/Tween 80/DSPE-PEG2000 as a surfactants mixture. To investigate the effects of liquid lipid in lipid core on itraconazole (ITZ) dissolution and release, TS/TO ratio was varied as 100/0, 90/10 and 80/20 (mg/mg). All HINP formulations showed particle size around 300 nm and polydispersity index below 0.3. The incorporation efficiencies of HINP formulations were above 80%, and more than 40 mg of ITZ was incorporated into each HINP formulation. In-vitro dissolution and release rate of ITZ from HINP increased as the amount of TO in lipid core increased. Compared with commercial formulations of ITZ, the pharmacokinetics of ITZ was improved after oral and parenteral administration of HINP formulations containing 0% or 10% of TO in lipid core. High payload itraconazole-incorporated lipid nanoparticles with a binary mixture lipid core have a great potential for the development of controlled release formulation of ITZ.

Pharmacokinetics and Relative Bioavailability of Orally Administered Innovator-Formulated Itraconazole Capsules and Solution in Healthy Dogs.

BackgroundItraconazole is commonly used for treatment of systemic and cutaneous mycoses in veterinary medicine. Two formulations, capsule and solution, are used interchangeably in dogs. However, marked differences in bioavailability have been reported in other species. Similar investigations have not been performed in dogs.ObjectiveTo determine and compare pharmacokinetics of itraconazole in dogs after oral administration of commercially available capsule and solution formulations intended for use in humans.AnimalsEight healthy, adult, purpose‐bred dogs.MethodsDogs received approximately 10 mg/kg of innovator‐formulated itraconazole solution and capsule PO in randomized, crossover design with a 10‐day washout period. To ensure maximal absorption, solution was administered to fasted dogs, whereas capsules were co‐administered with food. Blood samples were collected at predetermined time points, and plasma drug concentrations were measured using high‐pressure liquid chromatography. Pharmacokinetic parameters were determined with compartmental analysis.ResultsThe mean relative bioavailability of the capsule was 85% that of the solution, but drug absorption was variable, and overall drug concentrations were similar between formulations. Mean elimination half‐lives of both formulations were nearly identical at approximately 33 hours. Regardless of formulation, simulations suggest that a loading dose of 20 mg/kg, followed by 10 mg/kg once every 24 hours, will result in plasma concentrations considered to be adequate in most dogs.Conclusions and Clinical ImportanceContrary to findings reported in other species, overall drug exposures after capsule and solution administration are not substantially different in dogs. Despite some pharmacokinetic differences between itraconazole capsule and solution, formulation‐specific dosages do not appear to be necessary.

Population In Vitro-In Vivo Correlation Model Linking Gastrointestinal Transit Time, pH, and Pharmacokinetics: Itraconazole as a Model Drug

To establish an in vitro-in vivo correlation (IVIVC) model for Sporanox and SUBA-itraconazole formulations and to understand the impact of gastrointestinal (GI) pH and transit times on itraconazole dissolution and absorption. IVIVC was developed based on fed/fasted pharmacokinetic data from randomized cross-over trials, in vitro dissolution studies, and prior information about typical and between subject variability of GI pH and transit times. Data were analysed using the population modelling approach as implemented in NONMEM. Dissolution kinetics were described using first order models. The in vivo pharmacokinetics of itraconazole was described with a 2-compartment model with 4-transit absorption compartments. Pharmacokinetic profiles for fasted itraconazole periods were described based on the in vitro dissolution model, in vivo disposition model, and the prior information on GI pH and transit times. The IVIVC model indicated that drug dissolution in the fed state required an additional pH-independent dissolution pathway. The IVIVC models were presented in a 'Shiny' application. An IVIVC model was established and internally evaluated for the two itraconazole formulations. The IVIVC model provides more insight into the observed variability of itraconazole pharmacokinetics and indicated that GI pH and transit times influence in vivo dissolution and exposure.

Development of a Physiologically Based Pharmacokinetic Model for Itraconazole Pharmacokinetics and Drug-Drug Interaction Prediction.

Physiologically based pharmacokinetic (PBPK) modeling for itraconazole has been challenging due to highly variable in vitro d ata used for 'bottom-up' model building. Under-prediction of pharmacokinetics and drug-drug interactions (DDIs) following multiple doses of itraconazole has limited the use of PBPK model simulation to aid an itraconazole clinical DDI study design. The aim of this work is to develop an itraconazole PBPK model predominantly using a 'top-down' approach to enable a more accurate pharmacokinetic and DDI prediction. An itraconazole PBPK model describing itraconazole and hydroxyl-itraconazole (OH-ITZ) was constructed in Simcyp(®). The key parameters that govern the pharmacokinetic profile, including non-linear clearance (i.e., maximum rate of reaction [V max] and the Michaelis-Menten constant [K m]) and volume of distribution for both itraconazole and OH-ITZ, were redefined by leveraging existing in vivo data. Model verification was performed by comparing the simulated itraconazole and OH-ITZ pharmacokinetic profiles with the observed clinical data. Finally, the model was used to simulate clinical DDIs between itraconazole and midazolam. The developed PBPK model well-described the pharmacokinetics of itraconazole and OH-ITZ, and particularly captured their accumulation after repeated doses of itraconazole. This was verified with the observed data from 29 clinical studies where itraconazole solution or capsule was given as a single or multiple dose. The predicted DDI between itraconazole and midazolam was within 1.25-fold of the observed data for seven of ten studies and within 1.5-fold for nine of ten studies. The improvement of the itraconazole PBPK model increased our confidence in using PBPK model simulations to optimize clinical itraconazole DDI study design.

Determination of pharmacokinetics of itraconazole in healthy Indian subjects under fed condition and incurred sample analysis using a validated liquid chromatography tandem mass spectrometric method

This study aimed to determine Itraconazole Pharmacokinetics in healthy Indian subjects under fed condition and incurred sample analysis in human plasma by using a validated liquid chromatography tandem mass spectrometric method. A study in healthy human Indian subjects under fed condition was conducted to determine pharmacokinetics of two treatments of Itraconazole 100 mg capsules. Method validation was performed as per USFDA guidelines. Incurred Sample Reanalysis (ISR) was performed by random selection of subject samples. All the method validation parameters were found to be acceptable in terms of accuracy and precision. Results of all stability exercises in human plasma were within acceptable limits. The validated LCMS/MS method was used for sample analysis. A value of 96.7% for Itraconazole and 92.2% for Hydroxy Itraconazole was observed for incurred sample re-analysis. Arithmetic means for Cmax and AUC0→∞ were 103.699, 95.105 ng/ml and 1665.599, 1556.486 ng/ml.h, respectively, for Itraconazole and for...

A pilot trial of itraconazole pharmacokinetics in patients with metastatic breast cancer.

e13565 Background: Preclinical studies show that itraconazole (ITRA) has inhibitory activity against human umbilical vein endothelial cells. It also decreases angiogenesis with 67.5% reduction in new blood vessel formation in ITRA-treated mice vs. controls. The aim of this study is to determine the pharmacokinetics (PK) of ITRA in patients with metastatic breast cancer (MBC) and correlate measures of angiogenesis with plasma levels of the drug and its metabolite hydroxyitraconazole. Methods: ITRA was administered orally at 200mg daily to patients with MBC. A cycle consists of 28 days. Plasma levels of ITRA and hydroxyitraconazole were obtained at 2 and 4 weeks for PK. Plasma VEGF-A and TSP-1, serum bFGF and PlGF levels were obtained at baseline, 2, and 4 weeks. Spearman correlations (rs) of angiogenesis factors with plasma levels of ITRA and hydroxyitraconazole were computed. Toxicities, OS, TTP were determined. Results: 14 patients were enrolled, median age 62.5, with 13 being evaluable. 8 were hormone receptor-positive; 1 was HER2-positive. Median follow-up was 13.7 months. Median number of cycles was 2. Frequent AEs were fatigue (30.8%), anorexia (23.1%), insomnia (23.1%). Gr 3/4 toxicity was observed in only 1 patient (fatigue, insomnia, nausea/vomiting, dyspnea, hemorrhage, and pain). Median ITRA levels at 2 and 4 weeks were 181 and 202 ng/mL. Median hydroxyitraconazole levels were 331.5 and 337 ng/mL. Median bFGF and PlGF levels decreased with administration of ITRA from baseline to weeks 2 and 4. bFGF displayed high correlations with ITRA and hydroxyitraconazole at weeks 2 and 4 although not statistically significant (rs= -0.54 to -0.70). Plasma TSP-1 increased at weeks 2 and 4. VEGF-A levels increased from baseline to week 2, but decreased with drug administration during weeks 2 to 4. PlGF, TSP-1, VEGF-A did not correlate with drug levels. 1 patient had a PR, 3 SD, and 9 PD. Estimated TTP and OS were 1.8 and 19.3 months respectively. Conclusions: This is the first study evaluating PK of ITRA and effects on angiogenesis in MBC. Whilst reductions in pro-angiogenic factors and increases in TSP-1 (angiogenesis inhibitor) were observed with ITRA administration, our pilot study suggests a lack of correlation with drug or metabolite levels.

Pharmacokinetic interactions between ciprofloxacin and itraconazole in healthy male volunteers

To investigate the pharmacokinetic interaction between ciprofloxacin and itraconazole in healthy male volunteers. Ten healthy male volunteers were assigned into a 2-sequence, 3-period pharmacokinetic interaction study. In phase 1, all subjects were randomly assigned to receive 500 mg of ciprofloxacin alone and 200 mg of itraconazole alone twice daily for 7 days with a 14 day wash-out period in a crossover design. Phase 2 was performed 14 days after finishing phase 1, all subjects received 500 mg of ciprofloxacin in combination with 200 mg of itraconazole twice daily for 7 days. Ciprofloxacin and itraconazole pharmacokinetics were studied and adverse effects noted. Ciprofloxacin significantly increased the C(max) and AUC(0 - ∞) of itraconazole by 53.13% and 82.46%, respectively. The half-life and CL of itraconazole were not changed significantly. The combination of itraconazole and ciprofloxacin could therefore result in an increase in adverse drug reactions. Conversely, itraconazole had no significant effect on the pharmacokinetics of ciprofloxacin. Ciprofloxacin decreases the metabolism of itraconazole, most likely through inhibition of CYP3A4. The dosage of itraconazole should be reduced and its therapeutic outcome should be monitored closely when these two agents are concomitantly administered.

Effects of Compounding on Pharmacokinetics of Itraconazole in Black-Footed Penguins (Spheniscus demersus)

Itraconazole is used to treat and prevent aspergillosis in captive penguin colonies. Although commercial formulations of itraconazole are available, compounding is sometimes performed to decrease cost or to provide a different concentration of the drug. Using a two-way crossover design, the pharmacokinetics of both a commercially available oral itraconazole solution and a compounded oral itraconazole solution were compared in six black-footed penguins (Spheniscus demersus). Each itraconazole formulation was administered orally in frozen-thawed capelin at 7 mg/kg. Plasma itraconazole concentrations at time 0 (pretreatment), 20 and 40 min post-drug administration, and 1, 2, 4, 6, 8, and 12 hr post-drug administration were determined using reverse-phase high-performance liquid chromatography. Drug concentrations were analyzed using standard pharmacokinetic methods. Plasma clearance of the commercial itraconazole solution was more rapid than the clearance published for other species, possibly warranting more frequent dosing in black-footed penguins. Absorption of itraconazole, as determined by peak concentration and area under the curve, was significantly higher for the commercial formulation when compared to the compounded formulation, likely as a result of the presence of cyclodextrin, a carrier compound shown to improve oral absorption, in the commercial formulation. Extrapolating dosing regimens for compounded itraconazole formulations from regimens determined for commercial formulations warrants caution as a result of the significant differences in pharmacokinetics.

Accurate Prediction of Dose-Dependent CYP3A4 Inhibition by Itraconazole and Its Metabolites From In Vitro Inhibition Data

Inhibitory drug metabolites may contribute to drug-drug interactions (DDIs). The aim of this study was to determine the importance of inhibitory metabolites of itraconazole (ITZ) in in vivo cytochrome P450 (CYP) 3A4 inhibition. The pharmacokinetics of ITZ and midazolam (MDZ) were determined in six healthy volunteers in four sessions after administration of MDZ with and without oral ITZ. After doses of 50, 200, and 400 mg of ITZ, the clearance of orally administered MDZ decreased by 27, 74, and 83%, respectively. The in vivo half maximal inhibitory concentration (IC(50)) for ITZ ranged from 5 to 132 nmol/l in the six subjects. The metabolites of ITZ were estimated to account for ~50% of the total CYP3A4 inhibition, with the relative contribution increasing with time after ITZ dosing. Of the total of 18 interactions observed, 15 (84%) could be predicted within a twofold error margin, with improved accuracy observed when ITZ metabolites were included in the predictions. This study shows that the metabolites of ITZ contribute to CYP3A4 inhibition and need to be accounted for in quantitative rationalization of ITZ-mediated DDIs.

A simple, sensitive high-performance liquid chromatography -ultraviolet method for the quantification of concentration and steady-state pharmacokinetics of itraconazole and hydroxyitraconazole

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. 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. 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. 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.

Pharmacokinetics of itraconazole in diabetic rats.

After intravenous or oral administration of 10 mg/kg itraconazole to rats with streptozotocin-induced diabetes mellitus and to control rats, the total area under the plasma concentration-time curve from time 0 to 24 h (AUC0-24) for itraconazole and that for its metabolite, 7-hydroxyitraconazole, were similar between the two groups of rats. This may be explained by the comparable hepatic and intestinal intrinsic clearance rates for the disappearance of itraconazole and the formation of 7-hydroxyitraconazole in both groups of rats.