Plasma itraconazole concentrations during treatment of feline sporotrichosis.

Itraconazole (ITZ) is the most used drug to treat feline sporotrichosis; however, little is known about its pharmacokinetics in cats with this mycosis. The aim of this study was to determine plasma ITZ concentrations in cats with sporotrichosis treated with ITZ as monotherapy or in combination with potassium iodide (KI). Cats diagnosed with sporotrichosis received orally ITZ (100 mg/cat/day) or combination therapy with ITZ (100 mg/cat/day) and KI (2.5-5 mg/kg/day) in the case of worsening or stagnation of the clinical condition. At each monthly visit, blood samples were collected at an interval of 4 h for analysis of trough and peak plasma ITZ concentrations by HPLC. Clinical features and laboratory parameters were evaluated during follow-up. Sixteen cats were included in the study. The median plasma ITZ concentration of all cats was 0.75 µg/mL. The median plasma ITZ concentration was 0.5 µg/mL in cats that received ITZ monotherapy (n = 12) and 1.0 µg/mL in those treated with ITZ + KI (n = 4). The clinical cure rate was 56.3% (n = 9) and the median treatment duration was 8 weeks. Nine cats (56.3%) developed adverse clinical reactions, and hyporexia was the most frequent (n = 8; 88.9%). Serum alanine aminotransferase was elevated in four cats (25%). The median plasma ITZ concentration detected in cats was considered to be therapeutic (>0.5 µg/mL) and was reached after 4 weeks of treatment. Plasma ITZ concentrations were higher in cats that received ITZ + KI compared to those treated only with ITZ, suggesting pharmacokinetic synergism between these drugs.

Itraconazole is the most common therapy for feline sporotrichosis, and combination therapy with potassium iodide is used in nonresponsive cases. Our study showed that all cats achieved a therapeutic plasma concentration of itraconazole, with higher levels in cats treated with the combination therapy.

Practical Approach to Modeling the Impact of Amorphous Drug Nanoparticles on the Oral Absorption of Poorly Soluble Drugs.

Recently published studies have proposed that amorphous drug nanoparticles in gastrointestinal fluids may be beneficial for the absorption of poorly soluble compounds. Nanosized drug particles are known to provide rapid dissolution rates and, in some instances, a slight increase in solubility. However, in recent studies, the differences observed in vivo could not be explained solely by these attributes. Given the high dose and very low aqueous solubility of the study compounds, rapid equilibration to the drug-saturated solubility in gastrointestinal fluid would occur independent of the presence of nanoparticles. Alternatively, it has been proposed that drug nanoparticles (ca. ≤ 200 to 300 nm) may provide a "shuttle" for drug across the unstirred water layer (UWL) adjacent to the intestinal epithelium, particularly for low solubility/lipophilic compounds where absorption may be largely UWL-limited. This transport mechanism would result in a higher unbound drug concentration at the surface of the epithelium for absorption. This study evaluates this mechanism using a simple modification of the effective permeability to account for the effect of drug nanoparticles diffusing across the UWL. The modification can be made using inputs for solubility and nanoparticle size. The permeability modification was evaluated using three published case studies for amorphous formulations of itraconazole, anacetrapib, and enzalutamide, where the formation of amorphous drug nanoparticles upon dissolution resulted in improved drug absorption. Absorption modeling was performed using GastroPlus to assess the impact of the nanomodified permeability method on the accuracy of model prediction compared to in vivo data. Simulation results were compared to those for baseline simulations using an unmodified effective permeability. The results show good agreement using the nanomodified permeability, which described the data better than the standard baseline predictions. The nanomodified permeability method can be a suitable, fit-for-purpose in silico approach for evaluating or predicting oral absorption of poorly soluble, UWL-limited drugs from formulations that produce a significant number of amorphous drug nanoparticles.

Effective plasma concentrations of itraconazole and its active metabolite for the treatment of pulmonary aspergillosis.

BACKGROUND: Itraconazole (ITCZ) is used to treat pulmonary aspergillosis, but findings regarding the range of effective plasma concentrations are often contradictory. This study attempted to determine effective plasma concentrations of ITCZ and its active metabolite hydroxyitraconazole (OH-ITCZ) by retrospectively analyzing their relationships to clinical efficacy. METHODS: The study included 34 patients with pulmonary aspergillosis treated using ITCZ (mean age, 70 years). Each patient was treated with 200 mg ITCZ once daily (mean duration of treatment: 384 days). Plasma concentrations of ITCZ and OH-ITCZ at trough levels from 7 to 889 days after the start of treatment were determined using high-performance liquid chromatography. Clinical efficacy was assessed through the improvement clinical symptoms. RESULTS: Fifteen patients were classified as effective group and the other 19 patients as non-effective group. Mean (±standard deviation) ITCZ trough plasma concentration was significantly higher in effective group (1254 ± 924 ng/mL) than in non-effective group (260 ± 296 ng/mL). Mean OH-ITCZ plasma concentration was significantly higher in effective group (1830 ± 1031 ng/mL) than in non-effective group (530 ± 592 ng/mL). Receiver operating characteristic curve analysis revealed the optimal cutoff for ITCZ trough plasma concentration was 517 ng/mL, and 86.7% of effective group showed concentrations exceeding this value. The optimal cutoff for total ITCZ + OH-ITCZ plasma concentration was 1025 ng/mL, and 93.3% of effective group showed a concentration exceeding this value. CONCLUSIONS: Our findings indicate that effective plasma concentration ranges for the treatment of pulmonary aspergillosis begin at an ITCZ trough plasma concentration of 500 ng/mL and a total ITCZ + OH-ITCZ plasma concentration of 1000 ng/mL.

Plasma concentrations of itraconazole following a single oral dose in juvenile California sea lions (Zalophus californianus).

The objective of this study was to establish a single-dose pharmacokinetic profile for orally administered itraconazole in California sea lions (Zalophus californianus). Twenty healthy rehabilitated juvenile California sea lions were included in this study. Itraconazole capsules were administered orally with food at a target dose of 5-10 mg/kg. Blood samples were collected from each animal at 0 hr and at two of the following timepoints: 0.5, 1, 2, 4, 6, 8, 12, 24, 48, and 72 hr. Quantitative analysis of itraconazole in plasma samples was performed by high-performance liquid chromatography. An average maximum concentration of 0.22 µg/ml ± 0.11 was detected 4 hr after administration. The average concentration fell to 0.12 µg/ml ± 0.11 by 6 hr and 0.02 µg/ml ± 0.02 at 12 hr. At no point did concentrations reach 0.5 µg/ml, the concentration commonly accepted for therapeutic efficacy. While this formulation was well tolerated by the sea lions, oral absorption was poor and highly variable among individuals. These data indicate that a single oral dose of itraconazole given as a capsule at 5-10 mg/kg, under the conditions used in this study, does not achieve therapeutic plasma concentrations in California sea lions.

Preliminary Pilot Study of Itraconazole After a Single Oral Dose of a Veterinary Formulation Solution in African Penguins (Spheniscus demersus).

Aspergillosis is a common cause of morbidity and mortality in captive penguins. Itraconazole, an antifungal drug, is commonly used to treat aspergillosis infections in avian species; however, commercially available human formulations are costly, and studies have shown the effectiveness of compounded formulations to be unreliable. The US Food and Drug Administration (FDA) recently approved a veterinary formulation of itraconazole, Itrafungol, for use in cats. This study provides preliminary results from limited sampling evaluating whether this veterinary formulation is suitable for future studies in the African penguin (Spheniscus demersus). A 20 mg/kg PO itraconazole dose was administered to 9 African penguins. Blood samples were taken over the course of 24 hours; each sample was collected from a different bird to minimize stress to the animals. Plasma was analyzed by high-performance liquid chromatography for concentrations of itraconazole. The drug was absorbed in all penguins, and plasma concentrations in 5 of 9 penguins (56%) were found to be greater than the established therapeutic dose of 1.0 µg/ mL. To our knowledge, this is the first study that has investigated a 20 mg/kg dose of itraconazole in a penguin species. The small sample size limits the conclusions that can be drawn from this preliminary study. Nonetheless, we demonstrate encouraging evidence that the FDA-approved formulation of oral itraconazole solution should be considered for future study as a cost-effective treatment for aspergillosis in African penguins and other avian species.

Application of a physiologically based pharmacokinetic model for the prediction of mirabegron plasma concentrations in a population with severe renal impairment.

We previously verified a physiologically based pharmacokinetic (PBPK) model for mirabegron in healthy subjects using the Simcyp Simulator by incorporating data on the inhibitory effect on cytochrome P450 (CYP) 2D6 and a multi-elimination pathway mediated by CYP3A4, uridine 5'-diphosphate-glucuronosyltransferase (UGT) 2B7 and butyrylcholinesterase (BChE). The aim of this study was to use this PBPK model to assess the magnitude of drug-drug interactions (DDIs) in an elderly population with severe renal impairment (sRI), which has not been evaluated in clinical trials. We first determined the system parameters, and meta-analyses of literature data suggested that the abundance of UGT2B7 and the BChE activity in an elderly population with sRI was almost equivalent to and 20% lower than that in healthy young subjects, respectively. Other parameters, such as the CYP3A4 abundance, for an sRI population were used according to those built into the Simcyp Simulator. Second, we confirmed that the PBPK model reproduced the plasma concentration-time profile for mirabegron in an sRI population (simulated area under the plasma concentration-time curve (AUC) was within 1.5-times that of the observed value). Finally, we applied the PBPK model to simulate DDIs in an sRI population. The PBPK model predicted that the AUC for mirabegron with itraconazole (a CYP3A4 inhibitor) was 4.12-times that in healthy elderly subjects administered mirabegron alone, and predicted that the proportional change in AUC for desipramine (a CYP2D6 substrate) with mirabegron was greater than that in healthy subjects. In conclusion, the PBPK model was verified for the purpose of DDI assessment in an elderly population with sRI.

Population pharmacokinetics of itraconazole solution after a single oral administration in captive lesser flamingos (Phoeniconaias minor).

Aspergillosis is an infectious, non-contagious fungal disease of clinical importance in flamingo collections. Itraconazole is an antifungal drug commonly used in the treatment and prophylaxis of avian aspergillosis. Studies have shown that dosage regimes in birds vary based on different itraconazole presentation and administration methods. This investigation used a population pharmacokinetic approach to study itraconazole in lesser flamingos. Itraconazole was administered orally at 10 mg/kg to 17 flamingos. A sparse blood sampling was performed on the subjects, and samples were collected at 1, 2, 3, 5, 8, 12, 16, 21, and 24 hr post-drug administration. Twelve flamingos were sampled three times, three birds bled twice and two sampled once. Itraconazole in plasma was quantified using high-pressure liquid chromatography (HPLC). A one-compartment pharmacokinetic model with first order absorption was fitted to the data using nonlinear mixed effects modeling (NLME) to determine values for population parameters. We identified a long half-life (T½) of more than 75 hr and a maximum plasma concentration (CMAX ) of 1.69 µg/ml, which is above the minimal inhibitory concentrations for different aspergillus isolates. We concluded that plasma drug concentrations of itraconazole were maintained in a population of flamingos above 0.5 ug/ml for at least 24 hr after a single oral dose of 10 mg/kg of itraconazole solution.

Effects of Food and Omeprazole on a Novel Formulation of Super Bioavailability Itraconazole in Healthy Subjects.

To address the limited bioavailability and intolerance of the conventional itraconazole (ITZ) formulations, a new formulation labeled super bioavailability (SUBA) itraconazole has been developed; however, the specific effects of food and gastric pH are unknown. This study evaluated the pharmacokinetic profile of SUBA itraconazole under fasting and fed conditions, as well as with the concomitant administration of a proton pump inhibitor. First, the effect of food was assessed in an open-label, randomized, crossover bioavailability study of 65-mg SUBA itraconazole capsules (2 65-mg capsules twice a day) in healthy adults (n = 20) under fasting and fed conditions to steady-state levels. Second, an open-label, two-treatment, fixed-sequence comparative bioavailability study in healthy adults (n = 28) under fasted conditions compared the pharmacokinetics of a single oral dose of SUBA itraconazole capsules (2 65-mg capsules/day) with and without coadministration of daily omeprazole delayed-release capsules (1 40-mg capsule/day) under steady-state conditions. In the fed and fasted states, SUBA itraconazole demonstrated similar concentrations at the end of the dosing interval, with modestly lower total and peak ITZ exposure being shown when it was administered under fed conditions than when it was administered in the fasted state, with fed state/fasted state ratios of 78.09% (90% confidence interval [CI], 74.49 to 81.86%) for the area under the concentration-time curve over the dosing interval (14,183.2 versus 18,479.8 ng · h/ml), 73.05% (90% CI, 69.01 to 77.33%) for the maximum concentration at steady state (1,519.1 versus 2,085.2 ng/ml), and 91.53% (90% CI, 86.41 to 96.96%) for the trough concentration (1,071.5 versus 1,218.5 ng/ml) being found. When dosed concomitantly with omeprazole, there was a 22% increase in the total plasma exposure of ITZ, as measured by the area under the concentration-time curve from time zero to infinity (P = 0.0069), and a 31% increase in the peak plasma exposure of ITZ, as measured by the maximum concentration (P = 0.0083).

Reliable and Easy-To-Use Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Analysis of Fluconazole, Isavuconazole, Itraconazole, Hydroxy-Itraconazole, Posaconazole, and Voriconazole in Human Plasma and Serum.

BACKGROUND: A fast and easy-to-use liquid chromatography-tandem mass spectrometry method for the determination and quantification of 6 triazoles [fluconazole (FLZ), isavuconazole (ISZ), itraconazole (ITZ), hydroxy-itraconazole (OH-ITZ), posaconazole (PSZ), and voriconazole (VRZ)] in human plasma and serum was developed and validated for therapeutic drug monitoring. METHODS: Sample preparation was based on protein precipitation with acetonitrile and subsequent centrifugation. Isotope-labeled analogues for each analyte were used as internal standards. Chromatographic separation was achieved using a 50 × 2.1 mm, 1.9 µm polar Hypersil Gold C18 column and mobile phase consisting of 0.1% formic acid/acetonitrile (45%/55%, vol/vol) at a flow rate of 340 µL/min. The triazoles were simultaneously detected using a triple-stage quadrupole mass spectrometer operated in selected reaction monitoring mode with positive heated electrospray ionization within a single runtime of t = 3.00 minutes. RESULTS: Linearity of all azole concentration ranges was verified by the Mandel test and demonstrated for all azoles. All calibration curves were linear and fitted using least squares regression with a weighting factor of the reciprocal concentration. Limits of detection (µg/L/L) were FLZ, 9.3; ISZ, 0.3; ITZ, 0.6; OH-ITZ, 8.6; PSZ, 3.4; and VRZ, 2.1. The lower limits of quantitation (µg/L/liter) were FLZ, 28.3; ISZ, 1.0; ITZ, 1.7; OH-ITZ, 26.2; PSZ, 10.3; and VRZ, 6.3. Intraday and interday precisions ranged from 0.6% to 6.6% for all azoles. Intraday and interday accuracies (%bias) of all analytes were within 10.5%. In addition, we report on a 29-year-old white woman (94 kg body weight) with a history of acute myeloid leukemia who underwent stem cell transplantation. Because of diagnosis of aspergillus pneumonia, antifungal pharmacotherapy was initiated with different application modes and dosages of ISZ, and plasma concentrations were monitored over a time period of 6 months. CONCLUSIONS: A precise and highly sensitive liquid chromatography-tandem mass spectrometry method was developed that enables quantification of triazoles in plasma and serum matrix across therapeutically relevant concentration ranges. It was successfully implemented in our therapeutic drug monitoring routine service and is suitable for routine monitoring of antifungal therapy and in severely ill patients.

Plasma Concentration of Itraconazole in Patients With Hematologic Malignancies Treated With Itraconazole Oral Solution.

BACKGROUND: The prophylactic administration of itraconazole (ITCZ) is effective for preventing mycotic infections during chemotherapy in patients with hematologic malignancies. However, fungal infections can occur when the ITCZ does not reach an effective concentration. METHODS: We conducted a prospective study to monitor the plasma concentration of ITCZ and hydroxyl-ITCZ (OH-ITCZ) weekly and to verify whether the day 3 plasma concentration of ITCZ could predict the subsequent acquisition of an effective plasma concentration. RESULTS: A total of 39 patients who underwent 66 courses of chemotherapy were assessed in this study. An effective plasma concentration was achieved on day 7 in 34 of 63 patients (54%) and on day 14 in 35 of 59 patients (59%). A univariate analysis revealed that age, type of chemotherapy, and the body surface area were significantly associated with a high plasma concentration of ITCZ + OH-ITCZ. A linear regression analysis extracted the body surface area and the type of chemotherapy as significant factors. An receiver operating characteristic curve analysis revealed a day 3 plasma ITCZ + OH-ITCZ concentration of >656 ng/mL led to a plasma concentration that exceeded the minimum effective level on day 7; the sensitivity and specificity were 62% and 93%, respectively. CONCLUSIONS: This study showed that the measurement of the day 3 plasma concentration could lead to a better outcome in patients receiving chemotherapy for hematologic malignancies.

Comparing Azole Plasma Trough Levels in Lung Transplant Recipients: Percentage of Therapeutic Levels and Intrapatient Variability.

BACKGROUND: This study compared therapeutic azole plasma trough levels (APL) of the azole antimycotics itraconazole (ITR), voriconazole (VOR), and posaconazole (POS) in lung transplant recipients and analyzed the influencing factors. In addition, intrapatient variability for each azole was determined. METHODS: From July 2012 to July 2015, 806 APL of ITR, VOR, posaconazole liquid (POS-Liq), and posaconazole tablets (POS-Tab) were measured in 173 patients of the Munich Lung Transplantation Program. Therapeutic APL were defined as follows: ITR, ≥700 ng/mL; VOR, 1000-5500 ng/mL; and POS, ≥700 ng/mL (prophylaxis) and ≥1000 ng/mL (therapy). RESULTS: VOR and POS-Tab reached the highest number of therapeutic APL, whereas POS-Liq showed the lowest percentage (therapy: ITR 50%, VOR 70%, POS-Liq 38%, and POS-Tab 82%; prophylaxis: ITR 62%, VOR 85%, POS-Liq 49%, and POS-Tab 76%). Risk factors for subtherapeutic APL of all azoles were the azole dose (ITR, P < 0.001; VOR, P = 0.002; POS-Liq, P = 0.006) and age over 60 years (ITR, P = 0.003; VOR, P = 0.002; POS-Liq, P = 0.039; POS-Tab, P < 0.001). Cystic fibrosis was a significant risk factor for subtherapeutic APL for VOR and POS-Tab (VOR, P = 0.002; POS-Tab, P = 0.005). Double lung transplantation (LTx) was significantly associated with less therapeutic APL for VOR and POS-Liq (VOR, P = 0.030; POS-Liq, P < 0.001). Concomitant therapy with 80 mg pantoprazole led to significantly fewer therapeutic POS APL as compared to 40 mg (POS-Liq, P = 0.015; POS-Tab, P < 0.001). VOR displayed the greatest intrapatient variability (46%), whereas POS-Tab showed the lowest (32%). CONCLUSIONS: Our study showed that VOR and POS-Tab achieve the highest percentage of therapeutic APL in patients with LTx; POS-Tab showed the lowest intrapatient variability. APL are significantly influenced by azole dose, age, cystic fibrosis, type of LTx, and comedication with proton-pump inhibitors. Considering the high number of subtherapeutic APL, therapeutic drug monitoring should be integrated in the post-LTx management.

A rapid UPLC-MS/MS assay for the simultaneous measurement of fluconazole, voriconazole, posaconazole, itraconazole, and hydroxyitraconazole concentrations in serum.

BACKGROUND: Triazole antifungals are essential to the treatment and prophylaxis of fungal infections. Significant pharmacokinetic variability combined with a clinical need for faster turnaround times has increased demand for in-house therapeutic drug monitoring of these drugs, which is best performed using mass spectrometry-based platforms. However, technical and logistical obstacles to implementing these platforms in hospital laboratories have limited their widespread utilization. Here, we present the development and validation of a fast and simple ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to measure fluconazole, voriconazole, posaconazole, itraconazole, and hydroxyitraconazole in human serum suitable for incorporation into a hospital clinical laboratory. METHODS: Serum samples (20 µL) were prepared using protein precipitation in the presence of deuterated internal standards. Chromatographic separation was accomplished using reversed phase UPLC and analysis was performed using positive-mode electrospray ionization and collision-induced dissociation MS. RESULTS: Total analytical run time was 3 min. All analytes demonstrated linearity (r2>0.998) from 0.1 to 10 µg/mL (1-100 µg/mL for fluconazole), acceptable accuracy and precision (%DEV<15% and %CV<15% at all levels tested), suitable stability under relevant storage conditions, and correlated well with reference laboratory results. CONCLUSIONS: A simple and rapid UPLC-MS/MS method for monitoring multiple triazole antifungals was developed with a focus on the needs of hospital laboratories. The assay is suitable for clinical utilization and management of patients on these medications.

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, ß -0.161 and interval of confidence at 95%, IC -395.035; -62.383) and gender (ß 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.

Effect of a 150 mg dose of rifabutin on serum itraconazole levels in patients with coexisting chronic pulmonary aspergillosis and Mycobacterium avium complex lung disease.

Patients with coexisting chronic pulmonary aspergillosis and nontuberculous mycobacterial lung disease may undergo treatment with both the antifungal itraconazole and the antimycobacterial rifamycin. However, rifamycins interact with itraconazole. We examined the effects of a 150 mg dose of rifabutin on serum itraconazole levels and found significantly lower levels in 28 patients receiving itraconazole with rifabutin (median, 0.65 µg/ml) compared with 65 patients receiving itraconazole alone (median 3.45 µg/ml, P < 0.001). One-third of patients receiving itraconazole and rifabutin reached the therapeutic range of serum itraconazole concentration. Therapeutic drug monitoring is strongly recommended during concomitant use of rifabutin and itraconazole.

PHARMACOKINETICS, EFFICACY, AND SAFETY OF VORICONAZOLE AND ITRACONAZOLE IN HEALTHY COTTONMOUTHS (AGKISTRODON PISCIVORUS) AND MASSASAUGA RATTLESNAKES (SISTRURUS CATENATUS) WITH SNAKE FUNGAL DISEASE.

Snake fungal disease (SFD; Ophidiomyces ophiodiicola) is posing a significant threat to several free-ranging populations of pitvipers. Triazole antifungals have been proposed for the treatment of mycoses in reptiles; however, data are lacking about their safety and efficacy in snakes with SFD. Study 1 investigated in vitro susceptibility, and identified that plasma concentrations >250 ng/ml (voriconazole) and >1,000 ng/ml (itraconazole) may be effective in vivo for SFD. In Study 2, the pharmacokinetics after a single subcutaneous voriconazole injection were assessed in apparently healthy free-ranging cottonmouths (Agkistrodon piscivorus). Based on pilot-study results, four snakes were administered a single injection of voriconazole (5 mg/kg). One pilot snake and three full-study snakes died within 12 hr of voriconazole administration. All surviving snakes maintained plasma concentrations >250 ng/ml for 12-24 hr. In Study 3, two Eastern massasaugas (Sistrurus catenatus) and a timber rattlesnake (Crotalus horridus horridus) diagnosed with SFD were treated with voriconazole delivered by subcutaneous osmotic pumps. The timber rattlesnake (12.1-17.5 mg/kg/hr) reached therapeutic concentrations, whereas the massasaugas (1.02-1.6 mg/kg/hr) did not. In Study 4, the pharmacokinetics of a single 10-mg/kg per-cloaca dose of itraconazole (Sporanox®) was evaluated in seven apparently healthy free-ranging cottonmouths. Similarly, the plasma and tissue concentrations did not meet therapeutic concentrations based on in vitro data. The data presented in this report serve as an initial step toward understanding the pharmacokinetics, efficacy, and safety of triazole antifungals in pitviper species with SFD. Further study is needed to determine the appropriate dose and route of administration of triazole antifungals in pitviper species.

Plasma Concentrations of Itraconazole, Voriconazole, and Terbinafine When Delivered by an Impregnated, Subcutaneous Implant in Japanese Quail ( Coturnix japonica ).

Aspergillosis is a common fungal infection in both wild and pet birds. Although effective antifungal medications are available, treatment of aspergillosis can require months of medication administration, which entails stressful handling one or more times per day. This study examined the delivery of the antifungal drugs itraconazole, voriconazole, and terbinafine to Japanese quail ( Coturnix japonica ) via an impregnated implant. Implants contained 0.5, 3, 8, or 24 mg of itraconazole, voriconazole, or terbinafine. The implants were administered subcutaneously over the dorsum and between the scapulae. Blood was collected from birds before and 2, 7, 21, 42, and 56 days after implant placement. Plasma was analyzed by high-performance liquid chromatography for concentrations of itraconazole, voriconazole, or terbinafine, as appropriate. During the course of the study, targeted terbinafine concentrations were achieved in some birds at various time points, but concentrations were inconsistent. Itraconazole and voriconazole concentrations were also inconsistent and did not reach targeted concentrations. Currently, the implant examined in this study cannot be recommended for treatment of aspergillosis in avian species.

Alternate-day dosing of itraconazole in healthy adult cats.

The current available formulations of itraconazole are not ideal for dosing in cats. The capsular preparation often does not allow for accurate dosing, the oral solution is difficult to administer and poorly tolerated, and the bioavailability of compounded formulations has been shown to be poor in other species. The aim of this study was to evaluate every other day dosing of 100 mg itraconazole capsule in healthy adult cats. Ten healthy adult cats received a 100 mg capsule of itraconazole orally every 48 h for 8 weeks. Peak and trough serum concentrations of itraconazole were measured weekly using high-performance liquid chromatography (HPLC). Physical examination, complete blood count (CBC), and chemistry profiles were performed weekly. The dosage regimen achieved average therapeutic trough concentrations (>0.5 µg/mL) within 3 weeks. The protocol yielded no adverse effects in 8 of the 10 study cats, with affected cats recovering fully with discontinuation of the drug and supportive care. At 8 weeks, an average peak concentration of 1.79 ± 0.952 µg/mL (95% CI: 0.996-2.588) and an average trough concentration of 0.761 ± 0.540 µg/mL (95% CI: 0.314-1.216) were achieved. Overall, a 100 mg every other day oral dosage regimen for itraconazole in cats yielded serum concentrations with minimal fluctuation and with careful monitoring may be considered for treatment of cats with systemic fungal disease.

Effect of rifampin and rifabutin on serum itraconazole levels in patients with chronic pulmonary aspergillosis and coexisting nontuberculous mycobacterial infection.

We investigated the effects of rifampin and rifabutin on serum itraconazole levels in patients with chronic pulmonary aspergillosis. Serum itraconazole concentrations were significantly lower in patients who received itraconazole with rifampin (median, 0.1 µg/ml; P < 0.001) or rifabutin (median, 0.34 µg/ml; P < 0.001) than those receiving itraconazole alone (median, 5.92 µg/ml). Concomitant use of rifampin or rifabutin and itraconazole should be avoided in patients with chronic pulmonary aspergillosis and coexisting mycobacterial infections.

A reference laboratory experience of clinically achievable voriconazole, posaconazole, and itraconazole concentrations within the bloodstream and cerebral spinal fluid.

Interest in antifungal therapeutic-drug monitoring has increased due to studies demonstrating associations between concentrations and outcomes. We reviewed the antifungal drug concentration database at our institution to gain a better understanding of achievable triazole drug levels. Antifungal concentrations were measured by high-performance liquid chromatography (HPLC), ultraperformance liquid chromatography and single-quadrupole mass spectrometry (UPLC/MS), or a bioassay. For this study, only confirmed human bloodstream (serum or plasma) and cerebral spinal fluid (CSF) concentrations of voriconazole, posaconazole, and itraconazole were analyzed. The largest numbers of bloodstream and CSF samples were found for voriconazole (14,370 and 173, respectively). Voriconazole bloodstream concentrations within the range of 1 to 5.5 µg/ml represented 50.6% of samples. Levels below the lower limit of quantification (0.2 µg/ml) were observed in 14.6% of samples, and 10.4% of samples had levels of ≥5.5 µg/ml. CSF voriconazole levels ranged from undetectable to 15.3 µg/ml and were <0.2 µg/ml in 11% of samples. Posaconazole bloodstream concentrations were ≥0.7 and ≥1.25 µg/ml in 41.6% and 18.9% of samples, respectively. Posaconazole was detected in only 4 of 22 CSF samples (undetectable to 0.56 µg/ml). Itraconazole levels, as measured by UPLC/MS, were ≥0.5 µg/ml in 43.3% and were undetectable in 33.9% of bloodstream samples. In contrast, when measured by a bioassay, itraconazole/hydroxyitraconazole bloodstream concentrations were ≥1.0 µg/ml in 72.9% of samples and were undetectable in 18% of samples. These results indicate that there is marked variability in bloodstream concentrations achieved with these three azoles. In addition, many levels within the bloodstream for each azole and for voriconazole and posaconazole in the CSF were undetectable or below thresholds associated with efficacy.

The relationship between the success rate of empirical antifungal therapy with intravenous itraconazole and clinical parameters, including plasma levels of itraconazole, in immunocompromised patients receiving itraconazole oral solution as prophylaxis: a multicenter, prospective, open-label, observational study in Korea.

To identify the role of therapeutic drug monitoring of itraconazole (ITZ) in the setting of empirical antifungal therapy with intravenous (IV) ITZ, we performed a multicenter, prospective study in patients with hematological malignancies who had received antifungal prophylaxis with ITZ oral solution (OS). We evaluated the plasma levels of ITZ and hydroxy (OH) ITZ both before initiation of IV ITZ and on days 5-7 of IV ITZ. A total of 181 patients showed an overall success rate of 68.0 %. Prolonged baseline neutropenia and accompanying cardiovascular comorbidity were significantly associated with poor outcomes of the empirical antifungal therapy (P = 0.005 and P = 0.001, respectively). A significantly higher trough plasma level of OH ITZ per body weight was found in the patients who achieved success with empirical antifungal therapy (P = 0.036). There were no significant correlations between plasma concentrations of ITZ/OH ITZ (baseline or trough levels) and toxicities. Seven patients had a discontinuation of ITZ therapy due to toxicity. This study demonstrated that IV ITZ as empirical antifungal therapy was effective and therapeutic drug monitoring was helpful to estimate the outcome of empirical antifungal therapy in patients receiving antifungal prophylaxis with ITZ OS. To predict the outcome of empirical antifungal therapy with IV ITZ, we should evaluate baseline clinical characteristics and also perform the therapeutic drug monitoring of both ITZ and OH ITZ.