Fosmanogepix (APX001) Is Effective in the Treatment of Immunocompromised Mice Infected with Invasive Pulmonary Scedosporiosis or Disseminated Fusariosis.

There are limited treatment options for immunosuppressed patients with lethal invasive fungal infections due to Fusarium and Scedosporium Manogepix (MGX; APX001A) is a novel antifungal that targets the conserved Gwt1 enzyme required for localization of glycosylphosphatidylinositol-anchored mannoproteins in fungi. We evaluated the in vitro activity of MGX and the efficacy of the prodrug fosmanogepix (APX001) in immunosuppressed murine models of hematogenously disseminated fusariosis and pulmonary scedosporiosis. The MGX minimum effective concentration (MEC) for Scedosporium isolates was 0.03 µg/ml and ranged from 0.015 to 0.03 µg/ml for Fusarium isolates. In the scedosporiosis model, treatment of mice with 78 mg/kg and 104 mg/kg of body weight fosmanogepix, along with 1-aminobenzotriazole (ABT) to enhance the serum half-life of MGX, significantly increased median survival time versus placebo from 7 days to 13 and 11 days, respectively. Furthermore, administration of 104 mg/kg fosmanogepix resulted in an ∼2-log10 reduction in lung, kidney, or brain conidial equivalents/gram tissue (CE). Similarly, in the fusariosis model, 78 mg/kg and 104 mg/kg fosmanogepix plus ABT enhanced median survival time from 7 days to 12 and 10 days, respectively. A 2- to 3-log10 reduction in kidney and brain CE was observed. In both models, reduction in tissue fungal burden was corroborated with histopathological data, with target organs showing reduced or no abscesses in fosmanogepix-treated mice. Survival and tissue clearance were comparable to a clinically relevant high dose of liposomal amphotericin B (10 to 15 mg/kg). Our data support the continued development of fosmanogepix as a first-in-class treatment for infections caused by these rare molds.

Influence of Sustained Low-Efficiency Dialysis Treatment on Isavuconazole Plasma Levels in Critically Ill Patients.

Isavuconazole plasma concentrations were measured before and after sustained low-efficiency dialysis (SLED) treatment in 22 critically ill adult patients with probable invasive aspergillosis and underlying hematological malignancies. Isavuconazole levels were significantly lower after SLED treatment (5.73 versus 3.36 µg/ml; P < 0.001). However, even after SLED treatment, isavuconazole concentrations exceeded the in vivo MICs for several relevant Aspergillus species.

Optimization of Voriconazole Therapy for the Treatment of Invasive Fungal Infections in Adults.

Therapeutic concentrations of voriconazole in invasive fungal infections (IFIs) are ensured using a drug monitoring approach, which relies on attainment of steady-state pharmacokinetics. For voriconazole, time to reach steady state can vary from 5-7 days, not optimal for critically ill patients. We developed a population pharmacokinetic/pharmacodynamic model-based approach to predict doses that can maximize the net benefit (probability of efficacy-probability of adverse events) and ensure therapeutic concentrations, early on during treatment. The label-recommended 200 mg voriconazole dose resulted in attainment of targeted concentrations in ≥80% patients in the case of Candida spp. infections, as compared to only 40-50% patients, with net benefit ranging from 5.8-61.8%, in the case of Aspergillus spp. infections. Voriconazole doses of 300-600 mg were found to maximize the net benefit up to 51-66.7%, depending on the clinical phenotype (due to CYP2C19 status and pantoprazole use) of the patient and type of Aspergillus infection.

Pharmacodynamic Optimization for Treatment of Invasive Candida auris Infection.

Candida auris is an emerging multidrug-resistant threat. The pharmacodynamics of three antifungal classes against nine C. auris strains was explored using a murine invasive candidiasis model. The total drug median pharmacodynamic (PD) target associated with net stasis was a fluconazole AUC/MIC (the area under the concentration-time curve over 24 h in the steady state divided by the MIC) of 26, an amphotericin B Cmax/MIC (maximum concentration of drug in serum divided by the MIC) of 0.9, and a micafungin AUC/MIC of 54. The micafungin PD targets for C. auris were ≥20-fold lower than those of other Candida species in this animal model. Clinically relevant micafungin exposures produced the most killing among the three classes.

Fluconazole dosing predictions in critically-ill patients receiving prolonged intermittent renal replacement therapy: a Monte Carlo simulation approach.

Fluconazole is a renally-eliminated antifungal commonly used to treat Candida species infections. In critically-ill patients receiving prolonged intermittent renal replacement therapy (PIRRT), limited pharmacokinetic (PK) data are available to guide fluconazole dosing. We used previously-published fluconazole clearance data and PK data of critically-ill patients with acute kidney injury to develop a PK model with the goal of determining a therapeutic dosing regimen for critically-ill patients receiving PIRRT. Monte Carlo simulations were performed to create a virtual cohort of patients receiving different fluconazole dosing regimens. Plasma drug concentration-time profiles were evaluated on the probability of attaining a mean 24-hour area under the drug concentration-time curve to minimum inhibitory concentration ratio (AUC24h : MIC) of 100 during the initial 48 hours of antifungal therapy. At the susceptibility breakpoint of Candida albicans (2 mg/L), 93 - 96% of simulated subjects receiving PIRRT attained the pharmacodynamic target with a fluconazole 800-mg loading dose plus 400 mg twice daily (q12h or pre and post PIRRT) regimen. Monte Carlo simulations of a PK model of PIRRT provided a basis for the development of an informed fluconazole dosing recommendation when PK data was limited. This finding should be validated in the clinical setting.

Pharmacodynamics of Voriconazole in Children: Further Steps along the Path to True Individualized Therapy.

Voriconazole is the agent of choice for the treatment of invasive aspergillosis in children at least 2 years of age. The galactomannan index is a routinely used diagnostic marker for invasive aspergillosis and can be useful for following the clinical response to antifungal treatment. The aim of this study was to develop a pharmacokinetic-pharmacodynamic (PK-PD) mathematical model that links the pharmacokinetics of voriconazole with the galactomannan readout in children. Twelve children receiving voriconazole for treatment of proven, probable, and possible invasive fungal infections were studied. A previously published population PK model was used as the Bayesian prior. The PK-PD model was used to estimate the average area under the concentration-time curve (AUC) in each patient and the resultant galactomannan-time profile. The relationship between the ratio of the AUC to the concentration of voriconazole that induced half maximal killing (AUC/EC50) and the terminal galactomannan level was determined. The voriconazole concentration-time and galactomannan-time profiles were both highly variable. Despite this variability, the fit of the PK-PD model was good, enabling both the pharmacokinetics and pharmacodynamics to be described in individual children. (AUC/EC50)/15.4 predicted terminal galactomannan (P= 0.003), and a ratio of >6 suggested a lower terminal galactomannan level (P= 0.07). The construction of linked PK-PD models is the first step in developing control software that enables not only individualized voriconazole dosages but also individualized concentration targets to achieve suppression of galactomannan levels in a timely and optimally precise manner. Controlling galactomannan levels is a first critical step to maximizing clinical response and survival.

Demonstration of Therapeutic Equivalence of Fluconazole Generic Products in the Neutropenic Mouse Model of Disseminated Candidiasis.

Some generics of antibacterials fail therapeutic equivalence despite being pharmaceutical equivalents of their innovators, but data are scarce with antifungals. We used the neutropenic mice model of disseminated candidiasis to challenge the therapeutic equivalence of three generic products of fluconazole compared with the innovator in terms of concentration of the active pharmaceutical ingredient, analytical chemistry (liquid chromatography/mass spectrometry), in vitro susceptibility testing, single-dose serum pharmacokinetics in infected mice, and in vivo pharmacodynamics. Neutropenic, five week-old, murine pathogen free male mice of the strain Udea:ICR(CD-2) were injected in the tail vein with Candida albicans GRP-0144 (MIC = 0.25 mg/L) or Candida albicans CIB-19177 (MIC = 4 mg/L). Subcutaneous therapy with fluconazole (generics or innovator) and sterile saline (untreated controls) started 2 h after infection and ended 24 h later, with doses ranging from no effect to maximal effect (1 to 128 mg/kg per day) divided every 3 or 6 hours. The Hill's model was fitted to the data by nonlinear regression, and results from each group compared by curve fitting analysis. All products were identical in terms of concentration, chromatographic and spectrographic profiles, MICs, mouse pharmacokinetics, and in vivo pharmacodynamic parameters. In conclusion, the generic products studied were pharmaceutically and therapeutically equivalent to the innovator of fluconazole.

Evaluation of VT-1161 for Treatment of Coccidioidomycosis in Murine Infection Models.

Coccidioidomycosis, or valley fever, is a growing health concern endemic to the southwestern United States. Safer, more effective, and more easily administered drugs are needed especially for severe, chronic, or unresponsive infections. The novel fungal CYP51 inhibitor VT-1161 demonstrated in vitro antifungal activity, with MIC50 and MIC90 values of 1 and 2 µg/ml, respectively, against 52 Coccidioides clinical isolates. In the initial animal study, oral doses of 10 and 50 mg/kg VT-1161 significantly reduced fungal burdens and increased survival time in a lethal respiratory model in comparison with treatment with a placebo (P < 0.001). Oral doses of 25 and 50 mg/kg VT-1161 were similarly efficacious in the murine central nervous system (CNS) model compared to placebo treatment (P < 0.001). All comparisons with the positive-control drug, fluconazole at 50 mg/kg per day, demonstrated either statistical equivalence or superiority of VT-1161. VT-1161 treatment also prevented dissemination of infection from the original inoculation site to a greater extent than fluconazole. Many of these in vivo results can be explained by the long half-life of VT-1161 leading to sustained high plasma levels. Thus, the efficacy and pharmacokinetics of VT-1161 are attractive characteristics for long-term treatment of this serious fungal infection.

Clinical validation of the analysis of fluconazole in oral fluid in hospitalized children.

Fluconazole is a first-line antifungal agent for the treatment and prophylaxis of invasive candidiasis in pediatric patients. Pediatric patients are at risk of suboptimal drug exposure, due to developmental changes in gastrointestinal and renal function, metabolic capacity, and volume of distribution. Therapeutic drug monitoring (TDM) can therefore be useful to prevent underexposure of fluconazole in children and infants. Children, however, often fear needles and can have difficult vascular access. The purpose of this study was to develop and clinically validate a method of analysis to determine fluconazole in oral fluid in pediatric patients. Twenty-one paired serum and oral fluid samples were obtained from 19 patients and were analyzed using a validated liquid chromatography-tandem mass spectrometry (LC-MS-MS) method after cross-validation between serum and oral fluid. The results were within accepted ranges for accuracy and precision, and samples were stable at room temperature for at least 17 days. A Pearson correlation test for the fluconazole concentrations in serum and oral fluid showed a correlation coefficient of 0.960 (P < 0.01). The mean oral fluid-to-serum concentration ratio was 0.99 (95% confidence interval [CI], 0.88 to 1.10) with Bland-Altman analysis. In conclusion, an oral fluid method of analysis was successfully developed and clinically validated for fluconazole in pediatric patients and can be a noninvasive, painless alternative to perform TDM of fluconazole when blood sampling is not possible or desirable. When patients receive prolonged courses of antifungal treatment and use fluconazole at home, this method of analysis can extend the possibilities of TDM for patients at home.

Determination of voriconazole serum concentration by bioassay, a valid method for therapeutic drug monitoring for clinical laboratories.

We describe here a simple, fast, and reliable bioassay method for therapeutic drug monitoring of voriconazole. Fifty-eight clinical and external quality control samples were evaluated with this microbiological assay, and results were compared with those obtained with a previously validated chromatographic method. A good correlation between both assays was observed. This particular microbiological method was demonstrated to be simple and offers enough precision and accuracy to perform voriconazole therapeutic drug monitoring in laboratories without specialized equipment.

Population pharmacokinetic analysis of fluconazole to predict therapeutic outcome in burn patients with Candida infection.

The pharmacokinetic (PK) property of fluconazole might be significantly altered in major burn patients by medical interventions and physiologic changes. In this study, our aims were to investigate fluconazole PK in burn patients using a population approach and to recommend the optimal fluconazole regimen based upon the predicted therapeutic outcome. At steady state, blood samples for PK analysis were obtained from 60 burn patients receiving between 100 and ~400 mg fluconazole daily. A mixed-effect modeling was performed and the therapeutic outcome of antifungal therapy was predicted for 10,000 virtual patients using NONMEM (version 7.2). MIC values were sampled from the MIC distribution at the study site. An area under the free drug concentration-time curve (fAUC)/MIC measurement of >25 h was used as the criterion for therapeutic success. When the same dose was given, the plasma concentration of fluconazole was predicted to be lower in burn patients compared to the nonburn population because of the large PK parameter (clearance, volume of distribution) estimates and continuous renal replacement therapy (CRRT). This tendency was particularly predominant when the patients were within 30 postburn days. Based upon our findings, 400 mg/day fluconazole is recommended to obtain therapeutic successes in major burn patients.

Pharmacokinetics of different dosing strategies of oral posaconazole in patients with compromised gastrointestinal function and who are at high risk for invasive fungal infection.

The aim of this study was to assess different dosing strategies that may result in increased posaconazole bioavailability in patients with compromised gastrointestinal function and at high risk for invasive fungal infections. Patients undergoing chemotherapy and at risk for compromised gastrointestinal function received open-label posaconazole at 200 mg three times daily (TID) on days 1 to 8. Patients were randomized to one of three open-label dosing regimens of posaconazole on days 9 to 15: 200 mg TID, 400 mg twice daily (BID), or 400 mg TID. The plasma concentrations of interest on days 8 and 15 were 500 and 700 ng/ml, respectively; day 2 plasma concentrations of 250 and 350 ng/ml were chosen as levels that might result in steady-state concentrations of >500 and >700 ng/ml, respectively. A total of 75 patients enrolled; 52/75 (69%) completed the study, and 49/75 were included in the pharmacokinetic analyses. Mean plasma concentrations were 230, 346, and 637 ng/ml on days 2, 3, and 8, respectively. The day 15 values were 660, 930, and 671 ng/ml for 200 mg TID, 400 mg BID, and 400 mg TID, respectively. In 12 patients with a day 8 posaconazole concentration of <250 ng/ml, an overall benefit of the higher two doses was not apparent, suggesting that a subset of patients has low steady-state plasma concentrations. A change in dosing regimen on day 9 did not lead to higher exposures in these "poor absorbers" on day 15. Poor absorption may be enhanced with a high-fat meal, a nutritional supplement, or acidification.

Observational study of the clinical efficacy of voriconazole and its relationship to plasma concentrations in patients.

Voriconazole is approved for treating invasive fungal infections. We examined voriconazole exposure-response relationships for patients from nine published clinical trials. The relationship between the mean voriconazole plasma concentration (C(avg)) and clinical response and between the free C(avg)/MIC ratio versus the clinical response were explored using logistic regression. The impact of covariates on response was also assessed. Monte Carlo simulation was used to estimate the relationship between the trough concentration/MIC ratio and the probability of response. The covariates individually related to response were as follows: study (P < 0.001), therapy (primary/salvage, P < 0.001), primary diagnosis (P < 0.001), race (P = 0.004), baseline bilirubin (P < 0.001), baseline alkaline phosphatase (P = 0.014), and pathogen (yeast/mold, P < 0.001). The C(avg) for 72% of the patients was 0.5 to 5.0 µg/ml, with the maximum response rate (74%) at 3.0 to 4.0 µg/ml. The C(avg) showed a nonlinear relationship to response (P < 0.003), with a lower probability at the extremes. For patients with C(avg) < 0.5 µg/ml, the response rate was 57%. The lowest response rate (56%) was seen with a C(avg) ≥ 5.0 µg/ml (18% of patients) and was associated with significantly lower mold infection responses compared to yeasts (P < 0.001) but not with voriconazole toxicity. Higher free C(avg)/MIC ratios were associated with a progressively higher probability of response. Monte Carlo simulation suggested that a trough/MIC ratio of 2 to 5 is associated with a near-maximal probability of response. The probability of response is lower at the extremes of C(avg). Patients with higher free C(avg)/MIC ratios have a higher probability of clinical response. A trough/MIC ratio of 2 to 5 can be used as a target for therapeutic drug monitoring.

Modulators of very low voriconazole concentrations in routine therapeutic drug monitoring.

Very low voriconazole concentrations are commonly observed during therapeutic drug monitoring. Possible mechanisms include inappropriate dose selection, rapid metabolism (as a result of genetic polymorphisms or enzyme induction), and also nonadherence. We aimed to develop a method to distinguish between rapid metabolism of and nonadherence to voriconazole by quantification of voriconazole metabolites. In addition, the relevance of common genetic polymorphisms of CYP2C19 was assessed. In a retrospective study, samples with voriconazole concentrations 0.2 µg/mL or less in routine therapeutic drug monitoring (as quantified by high-performance liquid chromatography) were evaluated. Voriconazole and its N-oxide metabolite were quantified in residual blood using a highly sensitive liquid chromatography-tandem mass spectroscopy method (lower limit of quantitation = 0.03 µg/mL). Genetic polymorphisms of CYP2C19 were determined by real-time polymerase chain reaction using the hybridization probe format and the polymerase chain reaction-random fragment length polymorphism format. A total of 747 routine therapeutic drug monitoring plasma/blood samples of 335 patients treated with systemic voriconazole were analyzed and in 18.7% of all samples, voriconazole concentrations 0.2 µg/mL or less were found. In 32 samples (30 patients) with adequate dosage and timing of blood withdrawal, nonadherence was strongly suspected in seven patients because voriconazole-N-oxide concentrations were below 0.03 µg/mL, which was not observed in a reference group of 51 healthy volunteers with controlled drug intake. In 10 patients, of whom EDTA blood was available, the ultrarapid metabolizer genotype (CYP2C19*1\*17, CYP2C19*17\*17) was found in 80% and its prevalence was significantly higher as compared to a reference group (P = 0.02). In conclusion, quantification of voriconazole-N-oxide allowed for detection of suspected nonadherence in one of four patients with very low voriconazole concentrations. In the remaining patients, ultrarapid metabolism resulting from the CYP2C19*17 polymorphism appears to play a major role. Thus, in the case of voriconazole therapy failure, both nonadherence and genetic factors have to be considered.

Randomized, comparative, double-blind, double-dummy, multicenter trial of miconazole buccal tablet and clotrimazole troches for the treatment of oropharyngeal candidiasis: study of miconazole Lauriad® efficacy and safety (SMiLES).

BACKGROUND: Oropharyngeal candidiasis (OPC) is the most common opportunistic infection among persons infected with human immunodeficiency virus (HIV). Once-daily miconazole 50 mg buccal tablet (MBT) is a novel delivery system using an extended-spectrum azole with potent in vitro activity against many Candida species, including some that may be resistant to other azoles. METHODS: This phase 3, double-blind, double-dummy, multicenter trial evaluated 578 randomized patients with HIV infection and OPC. The study compared the efficacy and safety of MBT once daily with clotrimazole 10 mg troches (CT) 5 times daily for 14 days. The co-primary efficacy endpoints were clinical cure at test of cure (TOC) visit (days 17-22) in the intent-to-treat (ITT) and per protocol (PP) populations. RESULTS: Clinical cure rate at TOC visit for MBT-treated patients was statistically noninferior to CT-treated patients in both the ITT (61% vs 65%) and PP (68% vs 74%) populations. Secondary endpoints, safety, and tolerability were similar between treatment groups. CONCLUSIONS: In this large trial, once-daily MBT was shown to be noninferior to CT 5 times daily in the treatment of OPC in HIV-positive patients. MBT offers an effective, safe, and well-tolerated topical treatment option for OPC administered as a convenient once-daily dose.

Pharmacokinetics and absorption of posaconazole oral suspension under various gastric conditions in healthy volunteers.

A four-part, randomized, crossover study with healthy subjects evaluated the effects of gastric pH, the dosing frequency and prandial state, food consumption timing, and gastric motility on the absorption of posaconazole. In part 1, a single dose (SD) of posaconazole (400 mg) was administered alone or with an acidic beverage or a proton pump inhibitor (PPI), or both. In part 2, posaconazole (400 mg twice daily and 200 mg four times daily) was administered for 7 days with and without a nutritional supplement (Boost). In part 3, an SD of posaconazole (400 mg) was administered while the subjects were fasting and before, during, and after a high-fat meal. In part 4, an SD of posaconazole (400 mg) and the nutritional supplement were administered alone, with metoclopramide, and with loperamide. Compared to the results obtained with posaconazole alone, administration with an acidic beverage increased the posaconazole maximum concentration in plasma (C(max)) and the area under the concentration-time curve (AUC) by 92% and 70%, respectively, whereas a higher gastric pH decreased the posaconazole C(max) and AUC by 46% and 32%, respectively. Compared to the results obtained with posaconazole alone, posaconazole at 400 mg or at 200 mg plus the nutritional supplement increased the posaconazole C(max) and AUC by 65% and 66%, respectively, and by up to 137% and 161%, respectively. Administration before a high-fat meal increased the C(max) and the AUC by 96% and 111%, respectively, while administration during and after the meal increased the C(max) and the AUC by up to 339% and 387%, respectively. Increased gastric motility decreased the C(max) and the AUC by 21% and 19%, respectively. Strategies to maximize posaconazole exposure in patients with absorption difficulties include administration with or after a high-fat meal, with any meal or nutritional supplement, with an acidic beverage, or in divided doses and the avoidance of proton pump inhibitors.

Evidence for the mechanism of action of the antifungal phytolaccoside B isolated from Phytolacca tetramera Hauman.

Phytolaccoside B (1), an antifungal monodesmoside triterpenoid glycoside isolated from berries of Phytolacca tetramera Hauman (Phytolaccaceae), alters the morphology of yeasts and molds. The malformations were similar to those produced by enfumafungin, a known inhibitor of (1-->3)-beta-D-glucan synthase, an enzyme that catalyzes the synthesis of (1-->3)-beta-D-glucan, one of the major polymers of the fungal cell wall. However, enzymatic assays revealed that 1 did not inhibit (1-->3)-beta-D-glucan synthase, but it did produce a notable enhancement of the chitin synthase 1 activity and, concomitantly, a rise in chitin, another important polymer of the fungal cell walls. This finding was corroborated by fluorescence microscopy and also by quantification of the chitin. In addition, a 2-fold increase in the thickness of the fungal cell wall was observed with transmission electronic microscopy. On the other hand, 1 neither bound to ergosterol nor caused hemolysis of red blood cells, although some fungal membrane damage was observed at the MIC of 1.

Formulation of parenteral microemulsion containing itraconazole.

The aim of this study was to develop an aqueous parenteral formulation containing itraconazole (ITZ) using an o/w microemulsion system. A mixture of benzyl alcohol and medium chain triglyceride (3/1) was chosen as the oil phase. Pseudoternary phase diagrams of the microemulsion formations were constructed in order to determine the optimum ratio of oils, the concentration range of surfactant and cosurfactant and the optimum ratio between them. Consequently, the suitability of the chosen microemulsion system as a parenteral formulation was evaluated using droplet size analysis and hemolysis tests. Among the surfactants and cosurfactants screened, a mixture of polyoxyethylene (50) hydrogenated castor oil and ethanol (3/1) showed the largest o/w microemulsion region in the phase diagram. The average droplet size of the microemulsions was < 150 nm, and the hemolysis test showed this formulation to be nontoxic to red blood cells. The pharmacokinetic profiles of the ITZ-microemulsion for itraconazole and its major metabolite, hydroxyitraconazole, were compared with those of a PEG 400 solution and cyclodextrin formulations in rats. Overall, these results highlight the potential of an ITZ-microemulsion formulation for the parenteral route.