Therapeutic drug monitoring (TDM) of antifungal agents: guidelines from the British Society for Medical Mycology

Precision Therapy for Invasive Fungal Diseases

Invasive fungal infections (IFI) are a common infection-related cause of death in immunocompromised patients. Approximately 10 million people are at risk of developing invasive aspergillosis annually. Detailed study of the pharmacokinetics (PK) and pharmacodynamics (PD) of antifungal drugs has resulted in a better understanding of optimal regimens for populations, drug exposure targets for therapeutic drug monitoring, and establishing in vitro susceptibility breakpoints. Importantly, however, each is an example of a “one size fits all strategy”, where complex systems are reduced to a singularity that ensures antifungal therapy is administered safely and effectively at the level of a population. Clearly, such a notion serves most patients adequately but is completely counter to the covenant at the centre of the clinician–patient relationship, where each patient should know whether they are well-positioned to maximally benefit from an antifungal drug. This review discusses the current therapy of fungal infections and areas of future research to maximise the effectiveness of antifungal therapy at an individual level.

Consensus guidelines for improving patients' understanding of invasive fungal disease and related risk prevention in the haematology/oncology setting, 2021

Patients with invasive fungal disease (IFD) are at significant risk of morbidity and mortality. A productive partnership between patients, their carers/families, and the multidisciplinary team managing the infection and any underlying conditions, is essential. Sharing information and addressing knowledge gaps are required to ensure those at risk of IFD avoid infection, while those with suspected or confirmed infection optimise their therapy and avoid toxicities. This new addition to the Australian and New Zealand consensus guidelines for the management of IFD and antifungal use in the haematology/oncology setting outlines the key information needs of patients and their carers/families. It specifically addresses risk factor reduction, antifungal agents and adherence, and the risks and benefits of complementary and alternative therapies. Knowledge gaps are also identified to help inform the future research agenda.

Consensus guidelines for optimising antifungal drug delivery and monitoring to avoid toxicity and improve outcomes in patients with haematological malignancy and haemopoietic stem cell transplant recipients, 2021

Antifungal agents can have complex dosing and the potential for drug interaction, both of which can lead to subtherapeutic antifungal drug concentrations and poorer clinical outcomes for patients with haematological malignancy and haemopoietic stem cell transplant recipients. Antifungal agents can also be associated with significant toxicities when drug concentrations are too high. Suboptimal dosing can be minimised by clinical assessment, laboratory monitoring, avoidance of interacting drugs, and dose modification. Therapeutic drug monitoring (TDM) plays an increasingly important role in antifungal therapy, particularly for antifungal agents that have an established exposure-response relationship with either a narrow therapeutic window, large dose-exposure variability, cytochrome P450 gene polymorphism affecting drug metabolism, the presence of antifungal drug interactions or unexpected toxicity, and/or concerns for non-compliance or inadequate absorption of oral antifungals. These guidelines provide recommendations on antifungal drug monitoring and TDM-guided dosing adjustment for selected antifungal agents, and include suggested resources for identifying and analysing antifungal drug interactions. Recommended competencies for optimal interpretation of antifungal TDM and dose recommendations are also provided.

Implementation of a clinical decision rule for selecting empiric treatment for invasive aspergillosis in a setting with high triazole resistance

World-wide, emerging triazole resistance increasingly complicates treatment of invasive aspergillosis (IA). In settings with substantial (>10%) prevalence of triazole resistance, empiric combination therapy with both a triazole and liposomal amphotericin B (LAmB) can be considered because of the low yields of susceptibility testing. To avoid toxicity while optimizing outcome, a strategy with monotherapy would be preferable. A newly designed treatment algorithm based on literature and expert consensus provided guidance for empiric monotherapy with either voriconazole or LAmB. Over a four and a half year period, all adult patients in our hospital treated for IA were included and patient data were collected. An independent committee reviewed the attributability of death to IA for each patient. Primary outcomes were 30- and 100-day crude mortality and attributable mortality. In total, 110 patients were treated according to the treatment algorithm. Fifty-six patients (51%) were initially treated with voriconazole and 54 patients (49%) with LAmB. Combined attributable and contributable mortality was 13% within 30 days and 20% within 100 days. Treatment switch to LAmB was made in 24/56 (43%) of patients who were initially treated with voriconazole. Combined contributable and attributable 100-day mortality in this subgroup was 21% and was not increased when compared with patients initially treated with LAmB (P = 0.38). By applying a comprehensive clinical decision algorithm, an antifungal-sparing regime was successfully introduced. Further research is warranted to explore antifungal treatment strategies that account for triazole-resistance.

LAY SUMMARY

Due to resistance of Aspergillus against triazoles, combination therapy with liposomal amphotericin B (LAmB) is applied more often as primary therapy against invasive aspergillosis. This study presents the results of a decision tool which differentiated between triazole or LAmB monotherapy.

Antifungal Prophylaxis After Lung Transplantation: Where Are We Now?

BACKGROUND

Lung transplantation is an important treatment option for various end-stage lung diseases. However, survival remains limited due to graft rejection and infections. Despite that fungal infections are frequent and carry a bad prognosis, there is currently no consensus on efficacy, optimal drug, route, or duration of antifungal prophylaxis. This narrative review summarizes current strategies for antifungal prophylaxis after lung transplantation.

METHODS

English language articles in Embase, Pubmed, UptoDate, and bibliographies were used to assess the efficacy and safety of available antifungal agents for prophylaxis in adult lung transplant recipients.

RESULTS

Overall, there are limited high-quality data. Universal prophylaxis is more widely used and may be preferable over targeted prophylaxis. Both formulations of inhaled amphotericin B and systemic azoles are effective at reducing fungal infection rates, yet with their own specific advantages and disadvantages. The benefit of combination regimens has yet to be proven. Considering the post-transplant timing of the onset of fungal infections, postoperative prophylaxis during the first postoperative months seems indicated for most patients.

CONCLUSIONS

Based on existing literature, universal antifungal prophylaxis with inhaled amphotericin B and systemic voriconazole for at least 3-6 mo after lung transplantation may be advisable, with a slight preference for amphotericin B because of its better safety profile.

Ultra-performance liquid chromatography-tandem mass spectrometry for simultaneous determination of 12 anti-tumor drugs in human plasma and its application in therapeutic drug monitoring

The effectiveness and safety of anti-tumor drugs are clinically important issues, and their therapeutic drug monitoring (TDM) is recommended. This study aimed to develop an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for simultaneous TDM and exploration of clinical pharmacokinetics of anti-tumor drugs, including cyclophosphamide, ifosfamide, cisplatin, methotrexate, pemetrexed disodium, capecitabine, 5-fluorouracil, gemcitabine, doxorubicin, fulvestrant, tamoxifen, and irinotecan. After magnetic solid-phase extraction of plasma samples, the isotope internal standards and 12 anti-tumor drugs were separated using a ZORBAX Eclipse Plus C18 column (50.0 × 2.1 mm, 1.7 µm) with water containing 0.1% formic acid and acetonitrile as the mobile phase in a total run time of 5.0 min. The developed UPLC-MS/MS method was validated based on the Chinese Pharmacopoeia and the US Food and Drug Administration guidelines for bioanalytical method validation, including assessment of specificity, calibration curves, carryover, accuracy, crosstalk, precision, stability, recovery, dilution integrity, incurred sample reanalysis, and matrix effect. The results showed that a simple, fast, reliable, and specific UPLC-MS/MS method was developed and validated, and all the performance characteristics of the method met the requirements. The response function was established for concentration range of 0.10-25.00 μg/mL for gemcitabine, cyclophosphamide, ifosfamide, methotrexate, pemetrexed disodium, capecitabine, 5-fluorouracil, and cisplatin, and 0.05-12.50 μg/mL for doxorubicin, fulvestrant, tamoxifen, and irinotecan, with a coefficient of correlation of>0.9984 for all the compounds. The precision and accuracy of all the analytes were<6.5% and 5.9%, respectively. Hence, it could be used for TDM and exploration of pharmacokinetics of the aforementioned 12 anti-tumor drugs.

A Large Sample Retrospective Study on the Distinction of Voriconazole Concentration in Asian Patients from Different Clinical Departments

Voriconazole (VRZ) is widely used to prevent and treat invasive fungal infections; however, there are a few studies examining the variability and influencing the factors of VRZ plasma concentrations across different clinical departments. This study aimed to evaluate distinction of VRZ concentrations in different clinical departments and provide a reference for its reasonable use. From 1 May 2014 to 31 December 2020, VRZ standard rates and factors affecting the VRZ trough concentration were analyzed, and a multiple linear regression model was constructed. The standard rates of VRZ in most departments were above 60%. A total of 676 patients with 1212 VRZ trough concentrations using a dosing regimen of 200 mg q12h from seven departments were enrolled in the correlation analysis. The concentration distribution varied significantly among different departments (p < 0.001). Fifteen factors, including department, CYP2C19 phenotype, and gender, correlated with VRZ concentration. A multiple linear regression model was established as follows: VRZ trough concentration = 5.195 + 0.049 × age + 0.007 × alanine aminotransferase + 0.010 × total bilirubin − 0.100 × albumin − 0.004 × gamma-glutamyl transferase. According to these indexes, we can predict possible changes in VRZ trough concentration and adjust its dosage precisely and individually.

Recent Advances in Therapeutic Drug Monitoring of Voriconazole, Mycophenolic Acid, and Vancomycin: A Literature Review of Pediatric Studies

The review includes studies dated 2011-2021 presenting the newest information on voriconazole (VCZ), mycophenolic acid (MPA), and vancomycin (VAN) therapeutic drug monitoring (TDM) in children. The need of TDM in pediatric patients has been emphasized by providing the information on the differences in the drugs pharmacokinetics. TDM of VCZ should be mandatory for all pediatric patients with invasive fungal infections (IFIs). Wide inter- and intrapatient variability in VCZ pharmacokinetics cause achieving and maintaining therapeutic concentration during therapy challenging in this population. Demonstrated studies showed, in most cases, VCZ plasma concentrations to be subtherapeutic, despite the updated dosages recommendations. Only repeated TDM can predict drug exposure and individualizing dosing in antifungal therapy in children. In children treated with mycophenolate mofetil (MMF), similarly as in adult patients, the role of TDM for MMF active form, MPA, has not been well established and is undergoing continued debate. Studies on the MPA TDM have been carried out in children after renal transplantation, other organ transplantation such as heart, liver, or intestine, in children after hematopoietic stem cell transplantation or cord blood transplantation, and in children with lupus, nephrotic syndrome, Henoch-Schönlein purpura, and other autoimmune diseases. MPA TDM is based on the area under the concentration-time curve; however, the proposed values differ according to the treatment indication, and other approaches such as pharmacodynamic and pharmacogenetic biomarkers have been proposed. VAN is a bactericidal agent that requires TDM to prevent an acute kidney disease. The particular group of patients is the pediatric one. For this group, the general recommendations of the dosing may not be valid due to the change of the elimination rate and volume of distribution between the subjects. The other factor is the variability among patients that concerns the free fraction of the drug. It may be caused by both the patients' population and sample preconditioning. Although VCZ, MMF, and VAN have been applied in pediatric patients for many years, there are still few issues to be solve regarding TDM of these drugs to ensure safe and effective treatment. Except for pharmacokinetic approach, pharmacodynamics and pharmacogenetics have been more often proposed for TDM.

Fungal Endophthalmitis: A Comprehensive Review

Endophthalmitis is a serious ophthalmologic condition involving purulent inflammation of the intraocular spaces. The underlying etiology of infectious endophthalmitis is typically bacterial or fungal. The mechanism of entry into the eye is either exogenous, involving seeding of an infectious source from outside the eye (e.g., trauma or surgical complications), or endogenous, involving transit of an infectious source to the eye via the bloodstream. The most common organism for fungal endophthalmitis is Candida albicans. The most common clinical manifestation of fungal endophthalmitis is vision loss, but other signs of inflammation and infection are frequently present. Fungal endophthalmitis is a clinical diagnosis, which can be supported by vitreous, aqueous, or blood cultures. Treatment involves systemic and intravitreal antifungal medications as well as possible pars plana vitrectomy. In this review, we examine these essential elements of understanding fungal endophthalmitis as a clinically relevant entity, which threatens patients’ vision.

Machine learning-based method for tacrolimus dose predictions in Chinese kidney transplant perioperative patients

WHAT IS KNOWN AND OBJECTIVES

Tacrolimus (TAC), a first-line immunosuppressant in solid-organ transplant, has a narrow therapeutic window and large inter-individual variability, which affects its use in clinical practice. Successful predictions using machine learning algorithms have been reported in several fields. However, a comparison of 10 machine learning model-based TAC pharmacogenetic and pharmacokinetic dosing algorithms for kidney transplant perioperative patients of Chinese descent has not been reported. The objective of this study was to screen and establish an appropriate machine learning method to predict the individualized dosages of TAC for perioperative kidney transplant patients.

METHODS

The records of 2551 patients were collected from three transplant centres, 80% of which were randomly selected as a 'derivation cohort' to develop the dose prediction algorithm, while the remaining 20% constituted a 'validation cohort' to validate the final algorithm selected. Important features were screened according to our previously established population pharmacokinetic model of tacrolimus. The performances of the algorithms were evaluated and compared using R-squared and the mean percentage in the remaining 20% of patients.

RESULTS AND DISCUSSION

This study identified several factors influencing TAC dosage, including CYP3A5 rs776746, CYP3A4 rs4646437, haematocrit, Wuzhi capsules, TAC daily dose, age, height, weight, post-operative time, nifedipine and the medication history of the patient. According to our results, among the 10 machine learning models, the extra trees regressor (ETR) algorithm showed the best performance in the training set (R-squared: 1, mean percentage within 20%: 100%) and test set (R-squared: 0.85, mean percentage within 20%: 92.77%) of the derivation cohort. The ETR model successfully predicted the ideal TAC dosage in 97.73% of patients, especially in the intermediate dosage range (>5 mg/day to <8 mg/day), whereby the ideal TAC dosage could be successfully predicted in 99% of the patients.

WHAT IS NEW AND CONCLUSION

The results indicated that the ETR algorithm, which was chosen to establish the dose prediction model, performed better than the other nine machine learning models. This study is the first to establish ETR algorithms to predict TAC dosage. This study will further promote the individualized medication of TAC in kidney transplant patients in the future, which has great significance in ensuring the safety and effectiveness of drug use.

Evaluation of Posaconazole Dosing in Children and Young Adults: A Single-Center Review

OBJECTIVE

Initial posaconazole dosing regimens in children often do not achieve target concentrations, and data continue to support the need for higher initial dosing regimens. The objective of this study is to contribute to the current data regarding suboptimal posaconazole dosing in pediatric patients by retrospectively observing dosing strategies and subsequent drug concentrations.

METHODS

This study was conducted at a single institution in 27 patients aged 1 to 21 years. Patients who were initiated on any formulation of posaconazole for prophylaxis or treatment while admitted to the hospital were included. The primary outcome was to determine the percentage of pediatric patients who achieved the targeted trough concentration using their initial posaconazole dosing regimen. Secondary outcomes included percentage of patients who experienced a breakthrough invasive fungal infection (IFI), percentage of patients with elevated liver function tests (LFTs), and discontinuation for any reason.

RESULTS

There were 15 patients (55.5%) who reached desired trough serum concentration after the initial dosing regimen. The number of dose modifications to achieve the desired trough ranged from 1 to 3. Most patients received delayed-release tablets (n = 17), and the average doses for reaching prophylactic and treatment trough concentrations were 6.1 mg/kg/day and 11 mg/kg/day, respectively. There were 2 patients (7.4%) who experienced breakthrough IFI. Overall, 5 patients developed elevated LFTs and 7 patients discontinued treatment early.

CONCLUSIONS

The results describe a single population of pediatric patients, of whom 55% were able to achieve target trough concentrations of posaconazole with the initial dosing strategy used.

Population Pharmacokinetic Analysis and Dosing Optimization of Prophylactic Fluconazole in Japanese Patients with Hematological Malignancy

We conducted population pharmacokinetic (PPK) analysis and Monte Carlo simulations to determine the appropriate prophylactic dose of fluconazole to prevent invasive candidiasis in patients with hematological malignancies. Patients receiving chemotherapy or hematopoietic stem cell transplantation at Yokohama City University Hospital between November 2018 and March 2020 were included. Additionally, patients receiving oral fluconazole for prophylaxis were recruited. We set the free area under the curve/minimum inhibitory concentration (MIC) = 50 as the target and determined the largest MIC (breakpoint MIC) that could achieve more than 90% probability of target attainment. The blood fluconazole concentration of 54 patients (119 points) was used for PPK analysis. The optimal model was the one-compartment model with first-order administration and first-order elimination incorporating creatinine clearance (CLcr) as a covariate of clearance and body weight as a covariate of distribution volume. We conducted Monte Carlo simulation with fluconazole at 200 mg/day or 400 mg/day dosing schedules and patient body weight and CLcr ranging from 40 to 70 kg and 40–140 mL/min, respectively. The breakpoint MICs on the first dosing day and at steady state were 0.5–1.0 μg/mL and 1.0–2.0 μg/mL for 200 mg/day and 1.0–2.0 μg/mL and 2.0–4.0 μg/mL for 400 mg/day, respectively. The recommended dose was 400–700 mg/day for the loading dose and 200–400 mg/day for the maintenance dose. Our findings suggest that the optimal prophylactic dose of fluconazole in hematological malignancy patients depends on CLcr and body weight, and a sufficient loading and maintenance dose may be needed to completely prevent invasive candidiasis.

Chronopharmacology in Therapeutic Drug Monitoring-Dependencies between the Rhythmics of Pharmacokinetic Processes and Drug Concentration in Blood

The objective of the optimization of pharmacotherapy compliant with the basic rules of clinical pharmacology is its maximum individualization, ensuring paramount effectiveness and security of the patient's therapy. Thus, multiple factors that are decisive in terms of uniqueness of treatment of the given patient must be taken into consideration, including, but not limited to, the patient's age, sex, concomitant diseases, special physiological conditions (e.g., pregnancy, lactation, extreme age groups), polypharmacotherapy and polypragmasia (particularly related to increased risk of drug interactions), and patient's phenotypic response to the administered drug with possible genotyping. Conducting therapy while monitoring the concentration of certain drugs in blood (Therapeutic Drug Monitoring; TDM procedure) is also one of the factors enabling treatment individualization. Furthermore, another material, and yet still a marginalized pharmacotherapeutic factor, is chronopharmacology, which indirectly determines the values of drug concentrations evaluated in the TDM procedure. This paper is a brief overview of chronopharmacology, especially chronopharmacokinetics, and its connection with the clinical interpretation of the meaning of the drug concentrations determined in the TDM procedure.

Evaluating posaconazole, its pharmacology, efficacy and safety for the prophylaxis and treatment of fungal infections

INTRODUCTION

Invasive fungal diseases (IFDs) are a significant cause of morbidity and mortality among immunocompromised patients. Safe and effective antifungal medications used for prophylaxis and treatment are pivotal in their management. Posaconazole is a promising triazole antifungal agent.

AREAS COVERED

The authors discuss the pharmacological properties of posaconazole, including pharmacokinetics/pharmacodynamics, safety and tolerability profile, together with efficacy data for prophylaxis and treatment as well as its use in special populations based on current literature.

EXPERT OPINION

Posaconazole has a favorable safety and tolerability profile; however, caution is advised when co-administered with agents that are CYP3A4 inhibitors, because their concentration may significantly increase, and their levels should be closely monitored. It has an extended spectrum of activity against yeasts and filamentous fungi. It is successfully used as prophylaxis for patients with acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS) and post-hematopoietic cell transplantation (HCT) with graft-versus-host disease (GVHD). It is the first line treatment for oropharyngeal candidiasis and is also used as a salvage treatment for refractory IFDs. Currently available formulations include the oral suspension, delayed-release tablets and solution for intravenous infusion, all with different PK/PD properties and indications. Its use in children and adolescents is currently being examined in Phase-II clinical trials.

Experience of a Strategy Including CYP2C19 Preemptive Genotyping Followed by Therapeutic Drug Monitoring of Voriconazole in Patients Undergoing Allogenic Hematopoietic Stem Cell Transplantation

Many factors have been described to contribute to voriconazole (VCZ) interpatient variability in plasma concentrations, especially CYP2C19 genetic variability. In 2014, Hicks et al. presented data describing the correlation between VCZ plasma concentrations and CYP2C19 diplotypes in immunocompromised pediatric patients and utilized pharmacokinetic modeling to extrapolate a more suitable VCZ dose for each CYP2C19 diplotype. In 2017, in our hospital, a clinical protocol was developed for individualization of VCZ in immunocompromised patients based on preemptive genotyping of CYP2C19 and dosing proposed by Hicks et al., Clinical Pharmacogenetics Implementation Consortium (CPIC) clinical guidelines, and routine therapeutic drug monitoring (TDM). We made a retrospective review of a cohort of 28 immunocompromised pediatric patients receiving VCZ according to our protocol. CYP2C19 gene molecular analysis was preemptively performed using PharmArray^®. Plasma trough concentrations were measured by immunoassay analysis until target concentrations (1–5.5 μg/ml) were reached. Sixteen patients (57.14%) achieved VCZ trough target concentrations in the first measure after the initial dose based on PGx. This figure is similar to estimations made by Hicks et al. in their simulation (60%). Subdividing by phenotype, our genotyping and TDM-combined strategy allow us to achieve target concentrations during treatment/prophylaxis in 90% of the CYP2C19 Normal Metabolizers (NM)/Intermediate Metabolizers (IM) and 100% of the Rapid Metabolizers (RM) and Ultrarapid Metabolizers (UM) of our cohort. We recommended modifications of the initial dose in 29% (n = 8) of the patients. In RM ≥12 years old, an increase of the initial dose resulted in 50% of these patients achieving target concentrations in the first measure after initial dose adjustment based only on PGx information. Our experience highlights the need to improve VCZ dose predictions in children and the potential of preemptive genotyping and TDM to this aim. We are conducting a multicenter, randomized clinical trial in patients with risk of aspergillosis in order to evaluate the effectiveness and efficiency of VCZ individualization: VORIGENIPHARM (EudraCT: 2019-000376-41).

Therapeutic drug monitoring guided fluconazole therapy in a patient with cholangitis sepsis

Candida and other fungal species play an increasing role in nosocomial infections, including cholangitis and cholangiosepsis. Early diagnosis and prompt treatment are essential in successful patient outcomes. Fluconazole is an antifungal of choice in fluconazole-sensitive Candida infections. Little information is known about the fluconazole biliary excretion. Decreased tissue penetration may be one of the possible causes of treatment failure. Due to favorable pharmacokinetics, therapeutic drug monitoring of this antifungal has not been recommended routinely. In the presented case we report the successful therapeutic drug monitoring-guided fluconazole treatment in a patient with cholangitis and cholangiosepsis caused by fluconazole-sensitive Candida spp.

Population pharmacokinetics of a posaconazole tablet formulation in transplant adult allogeneic stem cell recipients

BACKGROUND

Posaconazole is an antifungal agent extensively used as a prophylaxis for invasive fungal infections (IFIs) in allogeneic stem cell transplant (SCT) recipients. Low posaconazole concentrations have been associated with reduced clinical response. The aim of this study was to develop a population pharmacokinetic (popPK) model of a posaconazole tablet formulation in allogeneic SCT adult recipients for supporting model-informed precision dosing (MIPD).

MATERIALS AND METHOD

Prospective observational study performed in adult allogeneic SCT recipients receiving posaconazole as prophylaxis for IFIs and followed up by a therapeutic drug monitoring (TDM) program. Posaconazole plasma concentrations were quantified using an ultra-high-performance liquid chromatography (UPLC) with UV detector. A popPK model was developed using NONMEM v.7.4.0. Deterministic and stochastic simulations were carried out with the final model to evaluate the differences across physiological variables with impact on drug exposure.

RESULTS

A one-compartment model with sequential absorption (zero and first order) and first order elimination described adequately 55 posaconazole concentrations from 36 patients. Higher doses of posaconazole were found to be required by males and patients with lower values of total serum proteins. A nomogram to estimate the posaconazole daily dose based on pharmacokinetic/pharmacodynamic (PKPD) criterion for males and females for different values of total proteins was developed.

CONCLUSIONS

Gender and total serum proteins have been identified as covariates influencing posaconazole CL/F in adult allogeneic SCT recipients receiving the delay-released tablet formulation. Additional studies are required to better characterize the absorption of posaconazole and implications on dosage recommendations together with potential safety concerns.

Computer-Assisted Analysis of Oral Antifungal Therapy in Chronic Rhinosinusitis with Airway Mycosis: a Retrospective Cohort Analysis

Environmental fungi are etiologically related to chronic rhinosinusitis (CRS) with airway mycosis, but their infectious role remains uncertain, in part because of potentially inadequate methods of disease quantitation. Our objective was to determine objective radiographic and symptomatic outcomes of oral antifungal therapy in adult patients with CRS and airway mycosis by using computer-assisted analysis. We conducted a retrospective study of 65 patients with CRS and culture-proven airway mycosis in a single-center referral-based academic practice, comparing paired sinus computed tomography (CT) scans and symptom scores prior to and during chronic oral antifungal therapy using computer-assisted analysis of sino-mucosal area (CAASMA). A comparator group received standard therapy without antifungals. Administration of antifungals was associated with significantly reduced sinus mucosal thickening as assessed by CAASMA (-6.85% absolute reduction; 95% confidence interval [CI], -11.8283 to -1.8717; P < 0.005), but not by Lund-Mackay score. In contrast, standard care alone was linked by CAASMA to enhanced mucosal thickening (4.14% absolute increase; 95% CI, -1.8066 to 10.0866; P < 0.005). Thirty of the 41 antifungal-treated patients (73%) showed decreased sinus mucosal burdens, while only 21 patients (43%) receiving standard therapy showed improved imaging (odds ratio [OR], 11.65; 95% CI, 3.2 to 42.2; P < 0.05). Nineteen patients (50%) noted improved symptoms at the time of a follow-up CT scan, while only 8 patients (20%) on standard therapy improved (OR, 6.21; 95% CI, 1.7 to 22.7; P < 0.05). These retrospective findings indicate that oral antifungals can reduce mucosal thickening and improve symptoms in CRS with airway mycosis. Randomized clinical trials are warranted to verify these findings.

Posaconazole treatment of refractory coccidioidomycosis in dogs

Background

The majority of dogs with coccidioidomycosis recover with administration of fluconazole or itraconazole, although some cases are refractory or the dogs do not tolerate administration of these medications.

Objectives

The objective was to describe the treatment outcomes and therapeutic monitoring of 8 dogs with refractory coccidioidomycosis treated with posaconazole.

Animals

Eight dogs with refractory coccidioidomycosis.

Methods

Retrospective case series. Medical records from Veterinary Specialty Center of Tucson were searched to identify dogs with refractory coccidioidomycosis that were treated with posaconazole. Clinical information and the results of monitoring trough serum posaconazole concentrations were retrieved.

Results

Eight dogs with refractory coccidioidomycosis were treated with 2.5 to 10 mg/kg per day of posaconazole. Six of 8 dogs recovered or developed clinical remission while administered posaconazole. Thirteen serum concentrations from 8 dogs tested were >1 μg/mL (range, 1.52 to >6 μg/mL) and the drug was well‐tolerated by 7 dogs. One dog required dosage reductions and treatment was ultimately discontinued because of hepatotoxicosis.

Conclusions and Clinical Importance

Posaconazole should be considered as a treatment option for dogs with refractory coccidioidomycosis. Monitoring of indicators of liver function or injury along with therapeutic drug monitoring is recommended to tailor dosage in the event of hepatic toxicosis.

Population Pharmacokinetics and Pharmacodynamics of Itraconazole for Disseminated Infection Caused by Talaromyces marneffei

First-line treatment of talaromycosis with amphotericin B deoxycholate (DAmB) is labor-intensive and toxic. Itraconazole is an appealing alternative antifungal agent. Pharmacokinetic data were obtained from 76 patients who were randomized to itraconazole in the Itraconazole versus Amphotericin B for Talaromycosis (IVAP) trial. Plasma levels of itraconazole and its active metabolite, hydroxyitraconazole, were analyzed alongside longitudinal fungal CFU counts in a population model. Itraconazole and hydroxyitraconazole pharmacokinetic variability was considerable, with areas under the concentration-time curve over 24 h (AUC24) of 3.34 ± 4.31 mg·h/liter and 3.57 ± 4.46 mg·h/liter (mean ± standard deviation), respectively. Levels of both analytes were low; itraconazole minimum concentration (Cmin) was 0.11 ± 0.16 mg/liter, and hydroxyitraconazole Cmin was 0.13 ± 0.17 mg/liter. The mean maximal rates of drug-induced killing were 0.206 and 0.208 log10 CFU/ml/h, respectively. There were no associations between itraconazole Cmin/MIC and time to sterilization of the bloodstream (hazard ratio [HR], 1.01; 95% confidence interval [CI], 0.99 to 1.03; P = 0.43), time to death (HR, 0.99; 95% CI, 0.96 to 1.02; P = 0.77), or early fungicidal activity (EFA) (coefficient, -0.004; 95% CI, -0.010 to 0.002; P = 0.18). Similarly, there was no relationship between AUC/MIC and time to sterilization of the bloodstream (HR, 1.00; 95% CI, 0.99 to 1.00; P = 0.50), time to death (HR, 1.00; 95% CI, 0.99 to 1.00; P = 0.91), or EFA (coefficient, -0.0001; 95% CI, -0.0003 to 0.0001; P = 0.19). This study raises the possibility that the failure of itraconazole to satisfy noninferiority criteria against DAmB for talaromycosis in the IVAP trial was a pharmacokinetic and pharmacodynamic failure.

Population Pharmacokinetics of Rezafungin in Patients with Fungal Infections

Rezafungin is a novel antifungal agent of the echinocandin class with potent activity against species of Candida and Aspergillus, including subsets of resistant strains, and Pneumocystis jirovecii. The objective of this analysis was to develop a population pharmacokinetic (PK) model to characterize the disposition of rezafungin in plasma following intravenous (IV) administration in healthy volunteers and in patients with candidemia and/or invasive candidiasis. The population PK model was based on a previous model from phase 1 data; formal covariate analyses were conducted to identify any relationships between subject characteristics and rezafungin PK variability. A four-compartment model with linear elimination and zero-order drug input provided a robust fit to the pooled data. Several statistically significant relationships between subject descriptors (sex, infection status, serum albumin, and body surface area [BSA]) and rezafungin PK parameters were identified, but none were deemed clinically relevant. Previous dose justification analyses conducted using data from phase 1 subjects alone are expected to remain appropriate. The final model provided a precise and unbiased fit to the observed concentrations and can be used to reliably predict rezafungin PK in infected patients.

Population pharmacokinetic model-guided optimization of intravenous voriconazole dosing regimens in critically ill patients with liver dysfunction

STUDY OBJECTIVES

This study aimed to establish a population pharmacokinetic (PPK) model of intravenous voriconazole (VRC) in critically ill patients with liver dysfunction and to explore the optimal dosing strategies in specific clinical scenarios for invasive fungal infections (IFIs) caused by common Aspergillus and Candida species.

DESIGN

Prospective pharmacokinetics study.

SETTING

The intensive care unit in a tertiary-care medical center.

PATIENTS

A total of 297 plasma VRC concentrations from 26 critically ill patients with liver dysfunction were included in the PPK analysis.

METHODS

Model-based simulations with therapeutic range of 2-6 mg/L as the plasma trough concentration (C_min ) target and the free area under the concentration-time curve from 0 to 24 h (ƒAUC₂₄ ) divided by the minimum inhibitory concentration (MIC) (ie, ƒAUC₂₄ /MIC) ≥25 as the effective target were performed to optimize VRC dosing regimens for Child-Pugh class A and B (CP-A/B) and Child-Pugh class C (CP-C) patients.

RESULTS

A two-compartment model with first-order elimination adequately described the data. Significant covariates in the final model were body weight on both central and peripheral distribution volume and Child-Pugh class on clearance. Intravenous VRC loading dose of 5 mg/kg every 12 h (q12h) for the first day was adequate for CP-A/B and CP-C patients to attain the C_min target at 24 h. The maintenance dose regimens of 100 mg q12h or 200 mg q24h for CP-A/B patients and 50 mg q12h or 100 mg q24h for CP-C patients could obtain the probability of effective target attainment of >90% at an MIC ≤0.5 mg/L and achieve the cumulative fraction of response of >90% against C. albicans, C. parapsilosis, C. glabrata, C. krusei, A. fumigatus, and A. flavus. Additionally, the daily VRC doses could be increased by 50 mg for CP-A/B and CP-C patients at an MIC of 1 mg/L, with plasma C_min monitored closely to avoid serious adverse events. It is recommended that an appropriate alternative antifungal agent or a combination therapy could be adopted when an MIC ≥2 mg/L is reported, or when the infection is caused by C. tropicalis but the MIC value is not available.

CONCLUSIONS

For critically ill patients with liver dysfunction, the loading dose of intravenous VRC should be reduced to 5 mg/kg q12h. Additionally, based on the types of fungal pathogens and their susceptibility to VRC, the adjusted maintenance dose regimens with lower doses or longer dosing intervals should be considered for CP-A/B and CP-C patients.

Future Directions for Clinical Respiratory Fungal Research

There has been a growing appreciation of the importance of respiratory fungal diseases in recent years, with better understanding of their prevalence as well as their global distribution. In step with the greater awareness of these complex infections, we are currently poised to make major advances in the characterization and treatment of these fungal diseases, which in itself is largely a consequence of post-genomic technologies which have enabled rational drug development and a path towards personalized medicines. These advances are set against a backdrop of globalization and anthropogenic change, which have impacted the world-wide distribution of fungi and antifungal resistance, as well as our built environment. The current revolution in immunomodulatory therapies has led to a rapidly evolving population at-risk for respiratory fungal disease. Whilst challenges are considerable, perhaps the tools we now have to manage these infections are up to this challenge. There has been a welcome acceleration of the antifungal pipeline in recent years, with a number of new drug classes in clinical or pre-clinical development, as well as new focus on inhaled antifungal drug delivery. The "post-genomic" revolution has opened up metagenomic diagnostic approaches spanning host immunogenetics to the fungal mycobiome that have allowed better characterization of respiratory fungal disease endotypes. When these advances are considered together the key challenge is clear: to develop a personalized medicine framework to enable a rational therapeutic approach.

Supratherapeutic Posaconazole Concentration in a Pediatric Transplant Patient With Confirmed Rhizopus Infection

There are a limited number of studies that guide dosing of posaconazole delayed-release (DR) tablets for the pediatric population. Current FDA-approved doses are only recommended for patients 13 years and older. For younger patients, providers are faced with the challenge of recommending posaconazole doses extrapolated from adult studies or choosing an alternative agent. We report on a case of a 10-year-old patient who experienced a supratherapeutic trough serum concentration and transaminitis after receiving the extrapolated adult dosage of posaconazole DR tablets (300 mg twice daily for the first day, followed by 300 mg daily) for 7 days. In the end, the patient required a smaller dose of 200 mg daily to achieve the desired trough target concentration for the treatment of a Rhizopus neck infection. Our findings highlight the need for additional studies to determine the optimal dosing of posaconazole DR tablets for children.

Predictors of Voriconazole Trough Concentrations in Patients with Child-Pugh Class C Cirrhosis: A Prospective Study

This prospective observational study aimed to clinically describe voriconazole administrations and trough concentrations in patients with Child–Pugh class C and to investigate the variability of trough concentration. A total of 144 voriconazole trough concentrations from 43 Child–Pugh class C patients were analyzed. The majority of patients (62.8%) received adjustments. The repeated measured trough concentration was higher than the first and final ones generally (median, 4.33 vs. 2.99, 3.90 mg/L). Eight patients with ideal initial concentrations later got supratherapeutic with no adjusted daily dose, implying accumulation. There was a significant difference in concentrations among the six groups by daily dose (p = 0.006). The bivariate correlation analysis showed that sex, CYP2C19 genotyping, daily dose, prothrombin time activity, international normalized ratio, platelet, and Model for end-stage liver disease score were significant factors for concentration. Subsequently, the first four factors mentioned above entered into a stepwise multiple linear regression model (variance inflation factor <5), implying that CYP2C19 testing makes sense for precision medicine of Child–Pugh class C cirrhosis patients. The equation fits well and explains the 34.8% variety of concentrations (R² = 0.348). In conclusion, it needs more cautious administration clinically due to no recommendation for Child–Pugh class C patients in the medication label. The adjustment of the administration regimen should be mainly based on the results of repeated therapeutic drug monitoring.

Predicting a therapeutic cut-off serum level of itraconazole in recalcitrant tinea corporis and cruris-A prospective trial

BACKGROUND

With rising resistance to terbinafine, and consistently high MICs to fluconazole and griseofulvin, itraconazole is being increasingly used as a first line drug for tinea corporis/cruris. However, inadequate clinical responses are often seen with it in spite of in vitro susceptibility. This is possibly related to a variable pharmacokinetic profile of itraconazole. The drug serum levels associated with the therapeutic outcome have not been defined in dermatophytic infections.

METHODS

Forty treatment naïve patients with tinea corporis/cruris were randomised to one of the three dose groups (100, 200 and 400 mg/day) of itraconazole. The drug serum levels of 21 of these patients were obtained after 2 weeks of treatment and correlated with the final clinical outcome and in vitro antifungal susceptibility data.

RESULTS

Trichophyton indotineae was identified by sequencing of ITS region of rDNA and TEF1α. All isolates were sensitive to itraconazole (Minimum Inhibitory Concentration (MICs) range: 0.06-0.5 µg/ml), while MICs to terbinafine were uniformly high (range 8-32 µg/ml). Thirty-seven patients (92.5%) achieved complete cure, while three failed treatment. Serum levels achieved with 400 mg/day were significantly higher than levels with 100 or 200 mg dose. All patients with itraconazole serum levels of >0.2 µg/ml were cured, while two out of the 10 patients with serum levels <0.2 µg/ml failed treatment.

CONCLUSIONS

Therapeutic failures are uncommon with itraconazole, and the prevalent strain in India has low itraconazole MICs. Treatment failure is likely with itraconazole serum levels of <0.2 µg/ml, while levels >0.2 µg/ml are consistently associated with a positive therapeutic outcome.

Concomitant Treatment with Voriconazole and Flucloxacillin: A Combination to Avoid

Background: Voriconazole is an antifungal drug used as one of the first-line treatments for invasive aspergillosis. This drug is extensively metabolized, predominantly via cytochrome P450 enzymes. An interaction between flucloxacillin and voriconazole, leading to subtherapeutic voriconazole concentrations, has previously been reported. We aimed to demonstrate that flucloxacillin independently influences voriconazole exposure. Methods: Patients from three Belgian hospitals, treated with a combination of voriconazole and flucloxacillin, were included in this retrospective study. Voriconazole concentrations were collected both in a timeframe with and without flucloxacillin co-treatment. Multivariate analyses were performed to study the independent effect of flucloxacillin treatment on voriconazole exposure and the possible influence of the flucloxacillin dose. Results: Thirty-three patients were included in this study and 145 trough concentrations (51 with, and 94 without concomitant flucloxacillin treatment) were analyzed. The median (IQR) voriconazole trough concentration sampled during flucloxacillin co-treatment was 0.5 (0–1.8) mg/L, whereas samples without flucloxacillin co-treatment had a median (IQR) voriconazole trough concentration of 3.5 (1.7–5.1) mg/L (p = 0.002), while receiving similar voriconazole doses. Subtherapeutic concentrations (<1 mg/L) were observed in 69% and 7% of the samples with flucloxacillin co-treatment versus samples without flucloxacillin co-treatment, respectively. Conclusion: This study shows that flucloxacillin co-treatment independently decreases voriconazole exposure. Caution is needed when these two drugs are administered simultaneously.

Implementation of a Dual-Column Liquid Chromatography-Tandem Mass-Spectrometry Method for the Quantification of Isavuconazole in Clinical Practice

Objectives  Therapeutic drug monitoring (TDM) of isavuconazole, which is a novel broad-spectrum antimycoticum against invasive fungal infections, ensures an effective exposure of the drug and minimizes the risk of toxicity. This study is aimed at evaluating the analytical performance of a dual-column liquid chromatography-tandem mass-spectrometry (LC-MS/MS) method for isavuconazole quantification.

Materials and Methods  The method was performed on a Voyager TSQ Quantum triple quadrupole instrument equipped with an Ultimate 3000 chromatography system (Thermo Fisher Scientific, San Jose, California, United States). Analytical and preanalytical requirements of the isavuconazole LC-MS/MS method were evaluated. Sample stability measurements were performed at room temperature (RT) and in serum tubes with separator gel.

Results  The isavuconazole LC-MS/MS method was linear over the concentration range of 0.2 to 12.8 mg/L. The coefficient of determination ( r² ) always exceeded 0.999. Within- and between-run precision ranged between 1.4 to 2.9% and 1.5 to 3.0%, the recovery between 93.9 and 102.7%. At RT, serum samples were stable for 3 days. Isavuconazole serum concentrations were significantly lower after incubation (18 hours) in serum tubes with separator gel at RT.

Conclusion  The dual-column isavuconazole LC-MS/MS is a reliable tool for the TDM of isavuconazole. Serum samples are stable for at least 3 days and should be collected in tubes without separator gel.

Comparison of ultra-performance liquid chromatography and ARK immunoassay for therapeutic drug monitoring of voriconazole

BACKGROUND

Therapeutic drug monitoring (TDM) of voriconazole is recommended for personalizing doses. The objective of this study was to compare the enzyme immunoassay developed by ARK^TM Diagnostics Inc. for the quantification of voriconazole adapted to the Architect C4000 autoanalyzer (Abbott®) with ultra-performance liquid chromatography using ultraviolet detector (UPLC-UV) method.

MATERIALS AND METHODS

Linearity, precision and accuracy of both methods were validated according to the Food and Drug Administration (FDA) and European Medicines Agency guidelines. The limit of quantification (LOQ) of the UPLC-UV method was determined experimentally. Both methods were applied to the analysis of 62 samples from patients. Correlation was evaluated by Passing-Bablok analysis and the concordance by the Bland-Altman method. Dosage recommendations were generated; the discordances according to the technique were evaluated.

RESULTS

All validation parameters determined for UPLC-UV met the criteria set out and LOQ of 0.1 μg/mL was established. However, when the enzyme immunoassay was used to determine concentrations ≤1 μg/ml, CVs were >20%. A linear correlation between both methods was found. However, an overestimation of immunoassay (systematic error of 0.39 μg/mL) was detected. In 11.3% of the samples, the differences in concentrations when they were determined by different techniques would imply a different therapeutic regime. These samples had concentrations close to 1 μg/mL.

CONCLUSION

Although both techniques can be used for TDM of voriconazole, when a value close to the lower limit of the therapeutic range is determined by the ARK^TM immunoassay, it would be better to verify the result by a non-automated technique to avoid possible underdosing.

Invasive Pulmonary Aspergillosis in Acute-on-Chronic Liver Failure Patients: Short-Term Outcomes and Antifungal Options

Introduction

Acute-on-chronic liver failure (ACLF) patients are susceptible to invasive fungal infections. We evaluated the prognosis and antifungal options in ACLF patients with invasive pulmonary aspergillosis (IPA).

Methods

ACLF patients with IPA from 15 hospitals were retrospectively screened from 2011 to 2018, and 383 ACLF patients without lung infections were included from a prospective cohort (NCT02457637). Demographic, laboratory, clinical data, and 28-day outcomes were documented in the two cohorts.

Results

ACLF patients with probable IPA (n = 145) had greater 28-day mortality (33.6% vs. 15.7%, p < 0.001) than those without (n = 383). The respiratory failure-associated 28-day mortality was greater in ACLF patients with IPA than in those without before (17.1% vs. 0.3%, p < 0.001) and after (16.0% vs. 0.0%, p < 0.001) propensity score matching in 116 pairs. IPA patients with lung injury had greater 28-day all-cause mortality (66.5% vs. 24.2%, p < 0.001) and IPA-associated mortality (45.8% vs. 8.1%, p < 0.001) than patients without lung injury (PaO2/FiO2 ≥ 400 mmHg). Antifungal therapy was prescribed to 139 of 145 patients, and 102 patients were treated with voriconazole alone (n = 59) or sequential/combined therapy (n = 43) with varying loading doses (100–800 mg) and daily maintenance doses (0–800 mg). A proposed optimal voriconazole regimen (loading dose, 200 mg twice daily; daily maintenance dose, 100 mg) achieved comparable short-term survival and optimal trough drug concentrations (1–5 μg/mL) on therapeutic drug monitoring in 26 patients.

Conclusion

Presence of IPA increases the short-term mortality of ACLF patients mainly due to respiratory failure. An optimal voriconazole regimen is needed for such critical patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00524-5.

Aspergillus fumigatus and aspergillosis: From basics to clinics

The airborne fungus Aspergillus fumigatus poses a serious health threat to humans by causing numerous invasive infections and a notable mortality in humans, especially in immunocompromised patients. Mould-active azoles are the frontline therapeutics employed to treat aspergillosis. The global emergence of azole-resistant A. fumigatus isolates in clinic and environment, however, notoriously limits the therapeutic options of mould-active antifungals and potentially can be attributed to a mortality rate reaching up to 100 %. Although specific mutations in CYP 51A are the main cause of azole resistance, there is a new wave of azole-resistant isolates with wild-type CYP 51A genotype challenging the efficacy of the current diagnostic tools. Therefore, applications of whole-genome sequencing are increasingly gaining popularity to overcome such challenges. Prominent echinocandin tolerance, as well as liver and kidney toxicity posed by amphotericin B, necessitate a continuous quest for novel antifungal drugs to combat emerging azole-resistant A. fumigatus isolates. Animal models and the tools used for genetic engineering require further refinement to facilitate a better understanding about the resistance mechanisms, virulence, and immune reactions orchestrated against A. fumigatus. This review paper comprehensively discusses the current clinical challenges caused by A. fumigatus and provides insights on how to address them.

Clinical pharmacokinetics and dose recommendations for posaconazole gastroresistant tablets in children with cystic fibrosis

Objectives

To investigate the population pharmacokinetics of posaconazole gastroresistant tablets in children with cystic fibrosis (CF) and perform simulations to recommend optimal doses.

Patients and methods

Children from a paediatric CF centre who had received posaconazole tablets and underwent therapeutic drug monitoring were identified from pharmacy records. Relevant clinical data were collated from case notes and electronic patient records and used to develop an allometrically scaled population pharmacokinetic model. A stepwise covariate model-building exercise evaluated the influence of interacting medicines and liver function.

Results

One hundred posaconazole serum concentrations were collected from 37 children with a median age of 14 years (range 7–17). Posaconazole pharmacokinetics were adequately described by a one-compartment model with inter-individual variability on clearance. Dose simulations demonstrated a 77%–83% probability of attaining a trough target of 1 mg/L with a dose of 300 mg every 12 h for two doses then 300 mg once daily (OD) in children aged 6–11 years; and 86%–88% with a dose of 400 mg every 12 h for two doses then 400 mg OD in adolescents aged 12–17 years. This dose scheme also yielded a 90% probability of achieving an AUC of 30 mg·h/L. AUC and trough concentration were highly correlated (r² = 0.98). Simulations showed that trough concentrations of >0.75 mg/L would exceed an AUC of 30 mg·h/L in 90% of patients.

Conclusions

A starting dose of 300 mg OD in those aged 6–11 years and 400 mg OD in those aged 12–17 years (following loading doses) yields a 90% probability of attaining an AUC of 30 mg·h/L.

Opportunities for Antimicrobial Stewardship Among Pediatric Patients Prescribed Combination Antifungal Therapy

OBJECTIVE

Combination antifungal therapy (CAF) may be prescribed to treat invasive fungal infections (IFIs). Data on the incidence of CAF among the pediatric population are limited. Antimicrobial stewardship for CAF includes therapeutic drug monitoring (TDM) and monitoring for adverse events. Primary outcome was to determine the incidence of CAF prescribed for documented proven, probable, and possible IFI. Secondary outcomes were to determine initial dose of antifungal therapy, determine incidence of adverse events, and evaluate our practice of TDM.

METHODS

Medical charts of patients who received CAF for proven, probable, or possible IFI within 6 years were reviewed. Patients age ≤18 years, prescribed CAF (defined as a second antifungal therapy started ≤72 hours of initial antifungal therapy) for at least 72 hours, and with normal liver function test results were included.

RESULTS

57 patients received CAF for 72 separate episodes: 35 episodes were proven IFI, 11 were probable IFI, and 26 were possible IFI. Initial dose of antifungal therapy varied, and 29.1% received a loading dose. A total of 10 patients experienced 14 adverse events that were related to antifungal therapy. In 63.8% of CAF episodes, TDM was conducted. Target antifungal concentrations were documented for 10 CAF episodes. Reason for discontinued of CAF was documented for 35 episodes. Of these episodes, 74% were discontinued after therapeutic antifungal concentrations were achieved.

CONCLUSIONS

There are opportunities for antimicrobial stewardship interventions in the method of TDM and monitoring for adverse events that could aid in management of CAF.

Pharmacological management of antifungal agents in pulmonary aspergillosis: an updated review

INTRODUCTION

Aspergillus may cause different types of lung infections: invasive, chronic pulmonary or allergic bronchopulmonary aspergillosis. Pharmacological management with antifungals poses as a challenge. Patients diagnosed with pulmonary aspergillosis are complex, as well as the problems associated with antifungal agents.

AREAS COVERED

This article reviews the pharmacology of antifungal agents in development and currently used to treat pulmonary aspergillosis, including the mechanisms of action, pharmacokinetics, pharmacodynamics, dosing, therapeutic drug monitoring and safety. Recommendations to manage situations that arise in daily clinical practice are provided. A literature search of PubMed was conducted on November 15^th, 2020 and updated on March 30^th, 2021.

EXPERT OPINION

Recent and relevant developments in the treatment of pulmonary aspergillosis have taken place. Novel antifungals with new mechanisms of action that extend antifungal spectrum and improve pharmacokinetic-related aspects, drug-drug interactions and safety are under current study. For those antifungals already marketed, new data related to pharmacokinetics, pharmacodynamics, dose adjustments in special situations, therapeutic drug monitoring and safety are available. To maximize efficacy and reduce the risk of associated toxicities, it is essential to choose the most appropriate antifungal; optimize its dose, interval, route of administration and length of treatment; and prevent side effects.

Model-Oriented Dose Optimization of Voriconazole in Critically Ill Children

This study aimed to employ a population pharmacokinetic (PK) model to optimize the dosing regimen of voriconazole (VRC) in children with a critical illness. A total of 99 children aged from 0.44 to 13.58 years were included in this study. The stability and predictive performance of the final model were evaluated by statistical and graphical methods. The optimal dosing regimen was proposed for children with different body weights, CYP2C19 phenotypes, and coadministrations with omeprazole. The PK of VRC was described by a two-compartment model with nonlinear Michaelis-Menten elimination. Body weight, CYP2C19 phenotype, and omeprazole were significant covariates on the maximum velocity of elimination (V_max), which had an estimated typical value of 18.13 mg · h^-1. Bayesian estimation suggested that the dose-normalized concentration and total exposure (peak concentration [C_max]/D, trough concentration [C_min]/D, and area under the concentration-time curve over 24 h [AUC₂₄]/D) were significantly different between extensive metabolizer (EM) patients and poor metabolizer (PM) patients. To achieve the target concentration early, two loading doses of 9 mg · kg^-1 of body weight every 12 h (q12h) were reliable for most children, whereas three loading doses of 6 to 7.5 mg · kg^-1 q8h were warranted for young children weighing ≤18 kg (except for PM patients). The maintenance doses decreased about 30 to 40% in PM patients compared to that in EM patients. For children aged <2 years, in EM patients, the maintenance dose could be as high as 9 mg · kg^-1. The maintenance dose of VRC was supposed to decrease slightly when coadministered with omeprazole. A population PK model of intravenous VRC for critically ill children has been successfully developed. It is necessary to adjust dosing regimens according to the CYP2C19 genotype. Optimal dosing regimens have been recommended based on the final model.

A Population Pharmacokinetic Modeling and Simulation Study of Posaconazole Oral Suspension in Immunocompromised Pediatric Patients: A Short Communication

BACKGROUND

Posaconazole oral suspension emerged as a promising candidate for prophylaxis of invasive fungal infections in immunocompromised children. Its pharmacodynamic advantages include a broad-spectrum activity and a favorable safety profile; however, they are overshadowed by its large pharmacokinetic (PK) variability, which might cause subtherapeutic exposure. The aim of this study was to develop a population (pop) PK model based on rich sampling data to better understand the PK of posaconazole oral suspension in pediatric patients.

METHODS

Data were obtained from a prospective interventional study involving hospitalized pediatric patients with a hematologic malignancy and prophylactically treated with posaconazole oral suspension. After constructing the popPK model, the probability of target attainment (PTA; 100% T ≥ 0.7 mg/L) for prophylaxis under fixed, body weight-based, and body surface area-based dosing was evaluated using Monte Carlo simulation.

RESULTS

Fourteen patients contributed 112 posaconazole plasma concentrations. The PK of posaconazole was adequately described by a 1-compartment model with lag time 2.71 hours [13%]; nonlinear bioavailability ED50 99.1 mg/m2 (fixed); first-order absorption rate constant 0.325 hour-1 [27%]; apparent volume of distribution 1150 L [34%]; and apparent clearance 15.4 L/h [24%] (∼70-kg individual). The bioavailability decreased in the presence of diarrhea and co-treatment with a proton pump inhibitor (PPI). The unexplained interindividual variability in posaconazole PK remained large. The PTA was <85%, irrespective of the simulated dosing strategy. Patients without diarrhea and not administered a PPI had the highest PTA (85% under the fixed 300-mg dosing 4 times per day).

CONCLUSIONS

Therapeutic drug monitoring is recommended during prophylactic posaconazole therapy in immunocompromised pediatric patients. Large-scale comparative studies are needed to characterize the PK variability between different posaconazole formulations in this cohort.

A case series of non-valvular cardiac aspergillosis in critically ill solid organ transplant and non-transplant patients and systematic review

INTRODUCTION

Non-valvular cardiac aspergillosis is a rare infection of the pericardium, myocardium or endocardium and is associated with a high mortality. There is a paucity of reports of non-valvular cardiac aspergillosis in critically ill and solid organ transplant (SOT) patients. The majority of cases have been reported in haemato-oncology patients, some of whom have undergone a bone marrow transplant.

OBJECTIVES

We describe four cases affected by non-valvular cardiac aspergillosis in the intensive care setting including a systematic review of this extremely rare infection which is associated with high mortality.

RESULTS

All four-patients died but presented with varying clinical, radiological and microbiological evidence of the disease. Three patients presented following complications after solid organ transplantation, two in the context of acute liver failure and emergency liver transplant and one several years after a double lung transplant. The last patient presented with necrotising gall stone pancreatitis, multi-organ failure and subsequently a prolonged intensive care unit (ICU) stay. On review of the literature, January 1955 to July 2019, 45 cases were identified, with different risk factors, clinical and radiological manifestations, treatment regimen and outcome.

CONCLUSION

Antemortem diagnosis of cardiac aspergillosis is difficult and rare, with no cases reporting positive blood culture results. Galactomannan serology has poor sensitivity in solid organ transplant patients, further reduced by prophylactic antimicrobial treatment, which is common in the ICU setting especially post-transplant patients. Due to the scarcity of cases, treatment is extrapolated from invasive aspergillosis management, with emphasis on early treatment with combination therapy.

Choice and duration of antifungal prophylaxis and treatment in high-risk haematology patients

PURPOSE OF REVIEW

This review aims to summarize available guidelines as well as the emerging evidence for the prevention and treatment of invasive fungal diseases in high-risk haematology patients.

RECENT FINDINGS

Primary mould-active prophylaxis is the strategy used in many centres to manage the risk of invasive fungal disease in high-risk haematology patients, and posaconazole remains the antifungal of choice for most of these patients. Data on the use of other antifungals for primary prophylaxis, including isavuconazole, are limited. There is considerable interest in identifying a strategy that would limit the use of mould-active agents to the patients who are the most likely to benefit from them. In this regard, a recent trial demonstrated that the preemptive strategy is noninferior to the empiric strategy. For primary treatment of invasive aspergillosis, two randomized trials found isavuconazole and posaconazole to be noninferior to voriconazole. Isavuconazole does not appear to require therapeutic drug monitoring.

SUMMARY

Prophylaxis and treatment of invasive fungal diseases in high-risk haematology patients is a rapidly evolving field. Critical clinical questions remain unanswered, especially regarding the management of suspected invasive fungal diseases breaking through mould-active prophylaxis, and the duration of antifungal therapy for invasive mould infections.

A Large Retrospective Assessment of Voriconazole Exposure in Patients Treated with Extracorporeal Membrane Oxygenation

BACKGROUND

Voriconazole is one of the first-line therapies for invasive pulmonary aspergillosis. Drug concentrations might be significantly influenced by the use of extracorporeal membrane oxygenation (ECMO). We aimed to assess the effect of ECMO on voriconazole exposure in a large patient population.

METHODS

Critically ill patients from eight centers in four countries treated with voriconazole during ECMO support were included in this retrospective study. Voriconazole concentrations were collected in a period on ECMO and before/after ECMO treatment. Multivariate analyses were performed to evaluate the effect of ECMO on voriconazole exposure and to assess the impact of possible saturation of the circuit's binding sites over time.

RESULTS

Sixty-nine patients and 337 samples (190 during and 147 before/after ECMO) were analyzed. Subtherapeutic concentrations (<2 mg/L) were observed in 56% of the samples during ECMO and 39% without ECMO (p = 0.80). The median trough concentration, for a similar daily dose, was 2.4 (1.2-4.7) mg/L under ECMO and 2.5 (1.4-3.9) mg/L without ECMO (p = 0.58). Extensive inter-and intrasubject variability were observed. Neither ECMO nor squared day of ECMO (saturation) were retained as significant covariates on voriconazole exposure.

CONCLUSIONS

No significant ECMO-effect was observed on voriconazole exposure. A large proportion of patients had voriconazole subtherapeutic concentrations.

Bioavailability of Single-Dose SUBA-Itraconazole Compared to Conventional Itraconazole under Fasted and Fed Conditions

Conventional itraconazole (C-ITZ) suffers from absorption variability. SUBA-itraconazole (S-ITZ) is more bioavailable than C-ITZ at steady state in a fed condition, but there are no data comparing the two under a fasted state. An open-label, single-dose, randomized, bioequivalence study was performed comparing S-ITZ to C-ITZ capsules under fasted and fed conditions in healthy adults measuring itraconazole and hydroxyitraconazole plasma levels. This study demonstrated less variability of S-ITZ compared to C-ITZ capsules under fasted conditions.

Treatment of allergic bronchopulmonary aspergillosis: from evidence to practice

Allergic bronchopulmonary aspergillosis (ABPA) is a complex pulmonary disorder caused by dysregulated immune responses against Aspergillus fumigatus. The disorder usually complicates the course of patients with asthma and cystic fibrosis. Patients with ABPA most often present with asthma that is poorly controlled despite inhaled corticosteroids and long-acting β2 agonists. The treatment of ABPA is complicated due to the occurrence of recurrent exacerbations and spontaneous remissions. The drugs used for treating ABPA include systemic glucocorticoids, antifungal agents and biologics, each with its own benefits and drawbacks. In this review, we illustrate the treatment pathway for ABPA in different situations, using a case-based approach. In each case, we present the options for treatment based on the available evidence from recent clinical trials.

A survey to describe common practices on antifungal monitoring among Spanish clinicians

INTRODUCTION

We developed a survey to obtain information on the monitoring practices of major systemic antifungals for treatment and prevention of serious fungal infection.

METHODS

The survey included questions relating to methodology and practice and was distributed among 137 colleagues of the Study Group of Medical Mycology (GEMICOMED) from July to December 2019.

RESULTS

Monitoring was routinely carried out by most respondents, mainly for voriconazole, and was more likely used to determine the efficacy of the dose administered and less for minimizing drug toxicity. Most responders did not follow the strategies of voriconazole dosage based on CYP2C19 genotyping. Monitoring of posaconazole, itraconazole, or other azole metabolites was not carried out or scarcely demanded. Most responders rarely used flucytosine in their clinical practice nor did they monitor it. According to the answers given by some responders, monitoring isavuconazole, amphotericin B, caspofungin and fluconazole exposure would be also interesting in daily clinical practice in selected patient populations.

CONCLUSIONS

The survey reveals common practices and attitudes towards antifungal monitoring, sometimes not performed as per best recommendations, offering an opportunity for education and research. Appropriate use of therapeutic drug monitoring may be an objective of antifungal stewardship programmes.

Management of posaconazole-induced pseudohyperaldosteronism

BACKGROUND

Posaconazole-induced pseudohyperaldosteronism (PIPH) has been associated with elevated posaconazole serum concentrations. Clinicians are faced with the difficult task of managing patients with PIPH while maintaining the efficacy of antifungal therapy. Commonly, modifications to posaconazole therapy are utilized in managing PIPH, including dosage reduction of posaconazole or switch to an alternative antifungal.

OBJECTIVES

To characterize the management of patients diagnosed with PIPH and their response to various therapeutic interventions.

METHODS

We retrospectively reviewed 20 consecutive adult patients diagnosed with PIPH. Patient data collected included blood pressure, electrolytes, endocrine laboratory values and posaconazole serum concentrations collected before and after therapeutic intervention.

RESULTS

Of 20 patients included, 17 patients (85%) underwent therapeutic modification, with posaconazole dose reduction (n = 11) as the most common change. Other modifications included discontinuation (n = 3), switch to an alternative antifungal (n = 2) and addition of spironolactone (n = 1). Clinical improvement (decrease in systolic blood pressure and increase in serum potassium) was observed in 9 of 17 patients (52.9%). An average decrease in systolic blood pressure of 7.1 mmHg and increase in serum potassium of 0.22 mmol/L was observed following therapeutic modification.

CONCLUSIONS

We report our experience with PIPH management, for which there is no universally effective strategy. We utilized a stepwise approach for management, starting with posaconazole dose reduction and repeat assessment of clinical and laboratory parameters. If resolution of PIPH is not achieved, an alternative triazole antifungal or the addition of an aldosterone antagonist are additional potential interventions. It is possible for PIPH to persist after therapeutic modification despite these interventions. Thus, early diagnosis and continuous monitoring is warranted.

Voriconazole: an audit of hospital-based dosing and monitoring and evaluation of the predictive performance of a dose-prediction software package

BACKGROUND

Therapeutic drug monitoring (TDM) is recommended to guide voriconazole therapy.

OBJECTIVES

To determine compliance of hospital-based voriconazole dosing and TDM with the Australian national guidelines and evaluate the predictive performance of a one-compartment population pharmacokinetic voriconazole model available in a commercial dose-prediction software package.

METHODS

A retrospective audit of voriconazole therapy at an Australian public hospital (1 January to 31 December 2016) was undertaken. Data collected included patient demographics, dosing history and plasma concentrations. Concordance of dosing and TDM with Australian guidelines was assessed. Observed concentrations were compared with those predicted by dose-prediction software. Measures of bias (mean prediction error) and precision (mean squared prediction error) were calculated.

RESULTS

Adherence to dosing guidelines for 110 courses of therapy (41% for prophylaxis and 59% for invasive fungal infections) was poor, unless oral formulation guidelines recommended a 200 mg dose, the most commonly prescribed dose (56% of prescriptions). Plasma voriconazole concentrations were obtained for 82% (90/110) of courses [median of 3 (range: 1-27) obtained per course]. A minority (27%) of plasma concentrations were trough concentrations [median concentration: 1.5 mg/L (range: <0.1 to >5.0 mg/L)]. Of trough concentrations, 57% (58/101) were therapeutic, 37% (37/101) were subtherapeutic and 6% (6/101) were supratherapeutic. The dose-prediction software performed well, with acceptable bias and precision of 0.09 mg/L (95% CI -0.08 to 0.27) and 1.32 (mg/L)2 (95% CI 0.96-1.67), respectively.

CONCLUSIONS

Voriconazole dosing was suboptimal based on published guidelines and TDM results. Dose-prediction software could enhance TDM-guided therapy.

Comparing posaconazole and itraconazole for antifungal prophylaxis in critically ill lung transplant recipients: Efficacy and plasma concentrations

BACKGROUND

Posaconazole and itraconazole are commonly used for systemic antifungal prophylaxis after lung transplantation. The aim of this study on critically ill lung transplant recipients was to assess the rate of adequate plasma concentrations and the frequency of fungal-induced transitions from antifungal prophylaxis to therapy after the administration of either posaconazole or itraconazole for systemic prophylaxis.

METHODS

Critically ill lung transplant recipients with postoperative posaconazole or itraconazole prophylaxis and therapeutic drug monitoring from February 2016 to November 2019 were retrospectively included in the study. Positive fungal cultures or Aspergillus antigen tests resulting in a transition from antifungal prophylaxis to therapy were analyzed from the first day of prophylaxis until 7 days after the last sample for each patient. Adequate plasma concentrations were defined as ≥500 µg/L for itraconazole and ≥700 µg/L for posaconazole.

RESULTS

Two hundred seventy-five samples from 73 patients were included in the analysis. Overall, 60% of the posaconazole and 55% of the itraconazole concentrations were subtherapeutic. Administration of posaconazole suspension resulted significantly (P < .01) more often in subtherapeutic concentrations than tablets (68% vs 10%). Patients treated with posaconazole showed less positive fungal records resulting in a transition from prophylaxis to therapy than patients treated with itraconazole (10% vs 33%, P-value: .029). The detection of a fungal pathogen was not associated with the measured plasma concentrations or the achievement of the target concentrations.

CONCLUSION

Our findings suggest that posaconazole should be used instead of itraconazole for systemic prophylaxis in critically ill lung transplant recipients.

A Review on Antifungal Efficiency of Plant Extracts Entrenched Polysaccharide-Based Nanohydrogels

Human skin acts as a physical barrier; however, sometimes the skin gets infected by fungi, which becomes more severe if the infection occurs on the third layer of the skin. Azole derivative-based antifungal creams, liquids, or sprays are available to treat fungal infections; however, these formulations show various side effects on the application site. Over the past few years, herbal extracts and various essential oils have shown effective antifungal activity. Additionally, autoxidation and epimerization are significant problems with the direct use of herbal extracts. Hence, to overcome these obstacles, polysaccharide-based nanohydrogels embedded with natural plant extracts and oils have become the primary choice of pharmaceutical scientists. These gels protect plant-based bioactive compounds and are effective delivery agents because they release multiple bioactive compounds in the targeted area. Nanohydrogels can be applied to infected areas, and due to their contagious nature and penetration power, they get directly absorbed through the skin, quickly reaching the skin's third layer and effectively reducing the fungal infection. In this review, we explain various skin fungal infections, possible treatments, and the effective utilization of plant extract and oil-embedded polysaccharide-based nanohydrogels.