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

Voriconazole therapeutic drug monitoring including analysis of CYP2C19 phenotype in immunocompromised pediatric patients with invasive fungal infections

PURPOSE

Therapeutic drug monitoring (TDM) of voriconazole (VCZ) should be mandatory for all pediatric patients with invasive fungal infections (IFIs). The narrow therapeutic index, inter-individual variability in VCZ pharmacokinetics, and genetic polymorphisms cause achieving therapeutic concentration during therapy to be challenging in this population.

METHODS

The study included 44 children suffering from IFIs treated with VCZ. Trough concentrations (Ctrough) of VCZ ware determined by the HPLC-FLD method. Identification of the CYP2C19*2 and CYP2C19*17 genetic polymorphisms was performed by PCR-RFLP. The correlation between polymorphisms and VCZ Ctrough was analyzed. Moreover, the effect of factors such as dose, age, sex, route of administration, and drug interactions was investigated.

RESULTS

VCZ was administered orally and intravenously at a median maintenance dosage of 14.7 mg/kg/day for a median of 10 days. The VCZ Ctrough was highly variable and ranged from 0.1 to 6.8 mg/L. Only 45% of children reached the therapeutic range. There was no significant association between Ctrough and dosage, age, sex, route of administration, and concomitant medications. The frequencies of variant phenotype normal (NM), intermediate (IM), rapid (RM) and ultrarapid metabolizers (UM) were 41%, 18%, 28%, and 13%, respectively. Ctrough of VCZ were significantly higher in NM and IM groups compared with RM, and UM groups.

CONCLUSION

The Ctrough of VCZ is characterized by inter-individual variability and a low rate of patients reaching the therapeutic range. The significant association exists in children between VCZ Ctrough and CYPC19 phenotype. The combination of repeated TDM and genotyping is necessary to ensure effective treatment.

How can we optimize antifungal use and stewardship in the treatment of acute leukemia?

INTRODUCTION

The global need for antifungal stewardship is driven by spreading antimicrobial and antifungal resistance. Triazoles are the only oral and relatively well-tolerated class of antifungal medications, and usage is associated with acquired resistance and species replacement with intrinsically resistant organisms. On a per-patient basis, hematology patients are the largest inpatient consumers of antifungal drugs, but are also the most vulnerable to invasive fungal disease.

AREAS COVERED

In this review we discuss available and forthcoming antifungal drugs, antifungal prophylaxis and empiric antifungal therapy, and how a screening based and diagnostic-driven approach may be used to reduce antifungal consumption. Finally, we discuss components of an antifungal stewardship program, interventions that can be employed, and how impact can be measured. The search methodology consisted of searching PubMed for journal articles using the term antifungal stewardship plus program, intervention, performance measure or outcome before 1 January 2024.

EXPERT OPINION

Initial focus should be on implementing effective antifungal stewardship programs by developing and implementing local guidelines and using interventions, such as post-prescription review and feedback, which are known to be effective. Technologies such as microbiome analysis and machine learning may allow the development of truly individualized risk-factor-based approaches to antifungal stewardship in the future.

A Score to Predict the Clinical Usefulness of Therapeutic Drug Monitoring: Application to Oral Molecular Targeted Therapies in Cancer

Therapeutic drug monitoring (TDM) involves measuring and interpreting drug concentrations in biological fluids to adjust drug dosages. In onco-hematology, TDM guidelines for oral molecular targeted therapies (oMTTs) are varied. This study evaluates a quantitative approach with a score to predict the clinical usefulness of TDM for oMTTs. We identified key parameters for an oMTT's suitability for TDM from standard TDM recommendations. We gathered oMTT pharmacological data, which covered exposure variability (considering pharmacokinetic (PK) impact of food and proton pump inhibitors), technical intricacy (PK linearity and active metabolites), efficacy (exposure-response relationship), and safety (maximum tolerated dose, and exposure-safety relationship). To assess the validity and the relevance of the score and define relevant thresholds, we evaluated molecules with prospective validation or strong recommendations for TDM, both in oncology and in other fields. By September 1, 2021, the US Food and Drug Administration (FDA) approved 67 oMTTs for onco-hematological indications. Scores ranged from 15 (acalabrutinib) to 80 (sunitinib) with an average of 48.3 and a standard deviation of 15.6. Top scorers included sunitinib, sorafenib, cabozantinib, nilotinib, and abemaciclib. Based on scores, drugs were categorized into low (< 40), intermediate (≥ 40 and < 60), and high (≥ 60) relevance for TDM. Notably, negative controls generally scored around or under 40, whereas positive controls had a high score across different indications. In this work, we propose a quantitative and reproducible score to compare the potential usefulness of TDM for oMTTs. Future guidelines should prioritize the TDM for molecules with the highest score.

Simultaneous determination of three tyrosine kinase inhibitors and three triazoles in human plasma by LC-MS/MS: applications to therapeutic drug monitoring and drug-drug interaction studies

Tyrosine kinase inhibitors (TKIs) and triazole antifungals are the first-line drugs for treating chronic myeloid leukemia (CML) and fungal infections, respectively, but both suffer from large exposure differences and narrow therapeutic windows. Moreover, these two types of drugs are commonly used together in CML patients with fungal infections. Multiple studies and guidelines have suggested the importance of therapeutic drug monitoring (TDM) of TKIs and triazoles. Currently, methods for the simultaneous determination of both types of drugs are limited. We developed a simple, rapid, and reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of three commonly used TKIs (imatinib, dasatinib, and nilotinib) and three commonly used triazoles (voriconazole, itraconazole, and posaconazole) in human plasma. The analytes were eluted on a Welch XB-C18 analytical column (50 × 2.1 mm, 5 µm) at 0.7 mL/min, using a gradient elution of 10 mM ammonium formate (A) and methanol-acetonitrile-isopropanol (80:10:10, v/v/v) containing 0.2 % formic acid (B) with a total analysis time of 3.5 min. The calibration curves were linear over the range from 20 to 4000 ng/mL for imatinib and nilotinib, from 2 to 400 ng/mL for dasatinib, and from 50 to 10,000 ng/mL for voriconazole, itraconazole, and posaconazole. Selectivity, accuracy, precision, recovery, matrix effect, and stability all met the validation requirements. The method was successfully used for TDM in CML patients who co-treated with both TKIs and triazoles. Drug-drug interaction analysis between TKIs and triazoles showed that a significant positive correlation was observed between imatinib and voriconazole, as well as dasatinib and voriconazole. Therefore, this method can be well applied in clinical TDM for patients receiving TKIs, triazoles, or both simultaneously.

Plasma itraconazole concentrations during treatment of feline sporotrichosis

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

Clinico-mycological and therapeutic updates on cutaneous dermatophytic infections in the era of Trichophyton indotineae

Trichophyton indotineae has emerged as a novel dermatophyte species resulting in treatment recalcitrant skin infections. While the earliest reports came from India, T. indotineae has now spread to many parts of the world and is rapidly becoming a global health concern. Accurate identification of T. indotineae requires elaborate mycological investigations which is beyond the domain of routine microbiology testing. Extensive, non-inflammatory and atypical presentations are commonly seen with this novel species. T. indotineae shows an alarmingly high rate of mutations in the squalene epoxidase gene leading to lowered in vitro susceptibility to terbinafine. This has also translated into a lowered clinical response and requirement of a higher dose and much longer durations of treatment with the drug. Although the species remains largely susceptible to itraconazole, prolonged treatment durations are required to achieve cure with itraconazole. Fluconazole and griseofulvin do not have satisfactory in vitro or clinical activity. Apart from requirement of prolonged treatment durations, relapse postsuccessful treatment is a distressing and yet unexplained consequence of this "species-shift." Use of third generation azoles and combinations of systemic antifungals is unwarranted as both have not demonstrated clear superiority over itraconazole given alone, and the former is an important class of drugs for invasive mycoses.

Promoting antifungal stewardship through an antifungal multidisciplinary team in a paediatric and adult tertiary centre in the UK

Background

Invasive fungal infections (IFIs) present significant challenges, especially among immunocompromised patients, with associated high morbidity, mortality and significant economic impact. Diagnostic difficulties and the emergence of antifungal resistance necessitates enhanced antifungal stewardship (AFS) efforts.

Methods

We report outcomes from a review of our multidisciplinary approach to AFS, based in a 1300-bed teaching hospital in the South-West of England. Retrospectively reviewing all adult and paediatric cases over 12 months in 2022, we investigated demographics, diagnosis, antifungal therapy and adherence to AFS advice, including clinical, mycological, financial and teamwork metrics. Data were extracted from our AFS database, supported by pharmacy records.

Results

The AFS multidisciplinary team (MDT) reviewed 111 patients, with 30 day and 1 year mortality of 22.7% and 35.4%, respectively. IFIs classified as proven accounted for 26%, with fungal pathogens identified in 36.3% of cases. Antifungal consumption (by 25.1%) and expenditure (by 59.9%) decreased from 2018 to 2022. The AFS MDT issued 324 recommendations, with a 93% acceptance rate.

Conclusions

Our approach to AFS, centred around a weekly MDT, demonstrated improvements in IFI management, antifungal consumption and cost-efficiency. This single-centre study highlights the value of a comprehensive, collaborative approach to AFS involving experts in mycology, infection, radiology, antifungal therapies and clinical teams. The programme's success in paediatric and adult populations and the near-universal acceptance of its recommendations show its potential as a model for replication. It represents a model for enhancing patient care and AFS practices, with future directions aimed at expanding service reach and the integration of further rapid diagnostic modalities.

ISCCM Position Statement on the Management of Invasive Fungal Infections in the Intensive Care Unit

Rationale

Invasive fungal infections (IFI) in the intensive care unit (ICU) are an emerging problem owing to the use of broad-spectrum antibiotics, immunosuppressive agents, and frequency of indwelling catheters. Timely diagnosis which is imperative to improve outcomes can be challenging. This position statement is aimed at understanding risk factors, providing a rational diagnostic approach, and guiding clinicians to optimize antifungal therapy.

Objectives

To update evidence on epidemiology, risk factors, diagnostic approach, antifungal initiation strategy, therapeutic interventions including site-specific infections and role of therapeutic drug monitoring in IFI in ICU and focus on some practice points relevant to these domains.

Methodology

A committee comprising critical care specialists across the country was formed and specific aspects of fungal infections and antifungal treatment were assigned to each member. They extensively reviewed the literature including the electronic databases and the international guidelines and cross-references. The information was shared and discussed over several meetings and position statements were framed to ensure their reliability and relevance in critical practice. The draft document was prepared after obtaining inputs and consensus from all the members and was reviewed by an expert in this field.

Results

The existing evidence on the management of IFI was updated and practice points were prepared under each subheading to enable critical care practitioners to streamline diagnosis and treatment strategies for patients in the ICU with additional detail on site-specific infections therapeutic drug monitoring.

Conclusion

This position statement attempts to address the management of IFI in immunocompetent and non-neutropenic ICU patients. The practice points should guide in optimization of the management of critically ill patients with suspected or proven fungal infections.

How to cite this article

Bhattacharya PK, Chakrabarti A, Sinha S, Pande R, Gupta S, Kumar AAK, et al. ISCCM Position Statement on the Management of Invasive Fungal Infections in the Intensive Care Unit. Indian J Crit Care Med 2024;28(S2):S20-S41.

Impact of Inflammatory Burden on Voriconazole Exposure in Oncohematological Pediatric Patients Receiving Antifungal Prophylaxis after Allogeneic HCT

(1) Background: The impact of inflammation on voriconazole exposure in oncohematological pediatric patients represents a debated issue. We aimed to investigate the impact of serum C-reactive protein (CRP), procalcitonin (PCT), and interleukin-6 (IL-6) levels on voriconazole exposure in oncohematological pediatric patients requiring allogeneic hematopoietic stem cell transplantation (HCT). (2) Methods: Pediatric patients undergoing allogeneic HCT and receiving therapeutic drug monitoring (TDM)-guided voriconazole as primary antifungal prophylaxis between January 2021 and December 2023 were included. The ratio between concentration and dose (C/D) of voriconazole was used as a surrogate marker of total clearance. A receiving operating characteristic curve analysis was performed by using CRP, PCT, or IL-6 values as the test variable and voriconazole C/D ratio > 0.188 or >0.375 (corresponding to a trough concentration value [Cmin] of 3 mg/L normalized to the maintenance dose of 16 mg/kg/day in patients of age < 12 years and of 8 mg/kg/day in those ≥12 years, respectively) as the state variable. Area under the curve (AUC) and 95% confidence interval (CI) were calculated. (3) Results: Overall, 39 patients were included. The median (IQR) voriconazole Cmin was 1.7 (0.7-3.0) mg/L. A CRP value > 8.49 mg/dL (AUC = 0.72; 95%CI 0.68-0.76; p < 0.0001), a PCT value > 2.6 ng/mL (AUC = 0.71; 95%CI 0.63-0.77; p < 0.0001), and an IL-6 value > 27.9 pg/mL (AUC = 0.80; 95%CI 0.71-0.88; p < 0.0001) were significantly associated with voriconazole overexposure. Consistent results were found in patients aged <12 and ≥12 years. (4) Conclusions: A single specific threshold of inflammatory biomarkers may be linked to a significantly higher risk of voriconazole exposure in oncohematological pediatric patients after HCT, irrespective of age. Adopting a TDM-guided strategy could be useful for minimizing the risk of voriconazole overexposure.

The Effect of Rifapentine and Rifampicin on Serum Voriconazole Levels Persist for 5 Days and 7 Days or More After Discontinuation in Tuberculosis Patients with Chronic Pulmonary Aspergillosis

Purpose

Voriconazole, a first-line therapeutic agent for chronic pulmonary aspergillosis, is metabolized by the cytochrome 450 enzymes, specifically CYP2C19 and CYP3A4. Rifampicin and rifapentine act as inducers of the cytochrome P450 enzyme. The current study explored the potential drug interactions arising from the co-administration of voriconazole with either rifampicin or rifapentine, as well as the duration of this effect on serum voriconazole levels after discontinuation of rifampicin or rifapentine.

Patients and Methods

A retrospective study was conducted in tuberculosis patients with chronic pulmonary aspergillosis. These patients underwent a combination therapy involving voriconazole and rifampicin or rifapentine, or they were treated with voriconazole after discontinuation of rifampicin or rifapentine. The serum concentrations of voriconazole at steady-state were monitored. Data on demographic characteristics and the serum voriconazole levels were used for statistical analyses.

Results

A total of 124 serum voriconazole concentrations from 109 patients were included in the study. The average serum concentration of voriconazole fell below the effective therapeutic range in patients treated with both voriconazole and rifampicin or rifapentine. Notably the co-administration of rifapentine led to a substantial (>70%) decrease in serum voriconazole levels in two patients. Moreover, this interfering effect persisted for at least 7 days following rifampicin discontinuation, while it endured for 5 days or more after discontinuation of rifapentine.

Conclusion

Concomitant use of voriconazole and rifampicin or rifapentine should be avoided, and it is not recommended to initiate voriconazole therapy within 5 or 7 days after discontinuation of rifapentine or rifampicin. Therapeutic drug monitoring not only provides a basis for the adjustment of clinical dose, but also serves as a valuable tool for identifying drug interactions.

Development and validation of a clinical risk score nomogram for predicting voriconazole trough concentration above 5 mg/L: a retrospective cohort study

The therapeutic range of voriconazole (VRC) is narrow, this study aimed to explore factors influencing VRC plasma concentrations > 5 mg/L and to construct a clinical risk score nomogram prediction model. Clinical data from 221 patients with VRC prophylaxis and treatment were retrospectively analyzed. The patients were randomly divided into a training cohort and a validation cohort at a 7:3 ratio. Univariate and binary logistic regression analysis was used to select independent risk factors for VRC plasma concentration above the high limit (5 mg/L). Four indicators including age, weight, CYP2C19 genotype, and albumin were selected to construct the nomogram prediction model. The area under the curve values of the training cohort and the validation cohort were 0.841 and 0.802, respectively. The decision curve analysis suggests that the nomogram model had good clinical applicability. In conclusion, the nomogram provides a reference for early screening and intervention in a high-risk population.

Posaconazole in paediatric malignancy and haematopoietic stem cell transplant: dosing to achieve therapeutic concentration

OBJECTIVES

Posaconazole is increasingly used for the treatment and prophylaxis of invasive fungal infections in immunocompromised children. We aimed to review evidence for paediatric posaconazole dosing regimens focusing on attainment of target concentrations and frequency of adverse effects.

METHODS

In May 2023, the Cochrane, Embase, MEDLINE and PubMed databases were searched for articles reporting posaconazole dosing in children with malignancy or post-haematopoietic stem cell transplantation. Studies reporting the attainment of target serum concentrations were included.

RESULTS

Overall, 24 studies were included. Eighteen studies of the oral suspension consistently reported poor attainment of target concentrations for prophylaxis (≥0.7 µg/mL, 12%-78%) despite high daily doses of 14-23 mg/kg/day (max. 1200 mg/day). Target attainment was significantly affected by gastric pH and food intake. Six studies of the delayed-release tablet (DRT) reported 58%-94% achieved concentrations ≥0.7 µg/mL, with the majority using lower doses of 4-12 mg/kg/day (max. 300 mg/day). Similarly, one study of powder for oral suspension found 67%-100% achieved target concentrations with a dose of 6 mg/kg/day (max. 300 mg/day). As expected, the IV formulation had high attainment of prophylaxis targets (81%-90%) with 6-10 mg/kg/day (max. 400 mg/day). All formulations were well tolerated, and no relationship between adverse effects and posaconazole concentrations was identified.

CONCLUSIONS

The required posaconazole dose in immunocompromised children varies depending on the formulation. The IV infusion had the highest attainment of therapeutic concentration followed by the DRT and powder for suspension. By contrast, the oral suspension had low attainment of target concentrations despite higher daily doses.

Clinical application of voriconazole in pediatric patients: a systematic review

The purpose of this study was to review the literature on the clinical use of voriconazole (VRC) in pediatric patients. MEDLINE, Embase, PubMed, Web of Science, and Cochrane Library were searched from January 1, 2000, to August 15, 2023 for relevant clinical studies on VRC use in pediatric patients. Data were collected based on inclusion and exclusion criteria, and a systematic review was performed on recent research related to the use of VRC in pediatric patients. This systematic review included a total of 35 observational studies among which there were 16 studies investigating factors influencing VRC plasma trough concentrations (Ctrough) in pediatric patients, 14 studies exploring VRC maintenance doses required to achieve target range of Ctrough, and 11 studies focusing on population pharmacokinetic (PPK) research of VRC in pediatric patients. Our study found that the Ctrough of VRC were influenced by both genetic and non-genetic factors. The optimal dosing of VRC was correlated with age in pediatric patients, and younger children usually required higher VRC doses to achieve target Ctrough compared to older children. Establishing a PPK model for VRC can assist in achieving more precise individualized dosing in children.

Triazole antifungal drug interactions-practical considerations for excellent prescribing

Systemic antifungal therapy is critical for reducing the mortality from many invasive and chronic fungal infections. Triazole antifungals are the most frequently prescribed antifungals but require attention to dosing and drug interactions. Nearly 600 severe drug-drug interactions and over 1100 moderate interactions requiring dose modifications are described or anticipated with systemic antifungal agents (see https://www.aspergillus.org.uk/antifungal-drug-interactions/). In this article, we address the common and less common, but serious, drug interactions observed in clinical practice with triazole antifungals, including a group of drugs that cannot be prescribed with all or most triazole antifungals (ivabradine, ranolazine, eplerenone, fentanyl, apomorphine, quetiapine, bedaquiline, rifampicin, rifabutin, sirolimus, phenytoin and carbamazepine). We highlight interactions with drugs used in children and new agents introduced for the treatment of haematological malignancies or graft versus host disease (midostaurin, ibrutinib, ruxolitinib and venetoclax). We also summarize the multiple interactions between oral and inhaled corticosteroids and triazole antifungals, and the strategies needed to optimize the therapeutic benefits of triazole antifungal therapy while minimizing potential harm to patients.

Ivosidenib significantly reduces triazole levels in patients with acute myeloid leukemia and myelodysplastic syndrome

BACKGROUND

Ivosidenib is primarily metabolized by CYP3A4; however, it induces CYP450 isozymes, including CYP3A4 and CYP2C9, whereas it inhibits drug transporters, including P-glycoprotein. Patients with acute myeloid leukemia are at risk of invasive fungal infections, and therefore posaconazole and voriconazole are commonly used in this population. Voriconazole is a substrate of CYP2C9, CYP2C19, and CYP3A4; therefore, concomitant ivosidenib may result in decreased serum concentrations. Although posaconazole is a substrate of P-glycoprotein, it is metabolized primarily via UDP glucuronidation; thus, the impact of ivosidenib on posaconazole exposure is unknown.

METHODS

Patients treated with ivosidenib and concomitant triazole with at least one serum trough level were included. Subtherapeutic levels were defined as posaconazole <700 ng/mL and voriconazole <1.0 µg/mL. The incidences of breakthrough invasive fungal infections and QTc prolongation were identified at least 5 days after initiation of ivosidenib with concomitant triazole.

RESULTS

Seventy-eight serum triazole levels from 31 patients receiving ivosidenib-containing therapy and concomitant triazole were evaluated. Of the 78 concomitant levels, 47 (60%) were subtherapeutic (posaconazole: n = 20 of 43 [47%]; voriconazole: n = 27 of 35 [77%]). Compared to levels drawn while patients were off ivosidenib, median triazole serum levels during concomitant ivosidenib were significantly reduced. There was no apparent increase in incidence of grade 3 QTc prolongation with concomitant azole antifungal and ivosidenib 500 mg daily.

CONCLUSIONS

This study demonstrated that concomitant ivosidenib significantly reduced posaconazole and voriconazole levels. Voriconazole should be avoided, empiric high-dose posaconazole (>300 mg/day) may be considered, and therapeutic drug monitoring is recommended in all patients receiving concomitant ivosidenib.

Evaluation of the pharmacokinetics of liposomal amphotericin B and analysis of the relationship between pharmacokinetics, efficacy and safety in patients with hematological diseases

INTRODUCTION

This study aimed to identify factors responsible for changes in blood concentrations of a liposomal formulation of amphotericin B (AMPH-B, L-AMB) and analyze the relationships between blood concentrations and efficacy or toxicity.

METHODS

L-AMB was administered to 30 patients being treated for hematological diseases. AMPH-B plasma concentrations were determined right before the initiation (Cmin) and at the end (Cmax) of infusion on at least 1 day, beginning on Day 3 of L-AMB treatment. The relationships of Cmin divided by dose (C/D ratio) to body weight, age, hepatic function, renal function, serum albumin, C-reactive protein (CRP), response, hypokalemia, and renal impairment were evaluated.

RESULTS

C/D ratio was not correlated with age, hepatic function, renal function, or serum albumin. Body weight adjusted C/D ratio was negatively correlated with CRP. Cmax and Cmin were compared between responders and non-responders, those with or without hypokalemia, and those with or without renal impairment. A higher Cmax in patients with hypokalemia was the only significant difference seen.

CONCLUSIONS

The negative correlation between CRP and plasma concentrations was likely caused by higher distribution of L-AMB from the blood to infected tissue in patients with a greater degree of infection, with a resulting decrease in plasma concentrations. AMPH-B plasma concentrations were not related to response. Higher Cmax of AMPH-B were observed in patients with hypokalemia, but no relationship between plasma concentration and renal toxicity was observed, suggesting that AMPH-B plasma concentrations appear to be minimally related to PD when used as L-AMB.

Renal Replacement Therapy as a New Indicator of Voriconazole Clearance in a Population Pharmacokinetic Analysis of Critically Ill Patients

AIMS

The pharmacokinetic (PK) profiles of voriconazole in intensive care unit (ICU) patients differ from that in other patients. We aimed to develop a population pharmacokinetic (PopPK) model to evaluate the effects of using extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) and those of various biological covariates on the voriconazole PK profile.

METHODS

Modeling analyses of the PK parameters were conducted using the nonlinear mixed-effects modeling method (NONMEM) with a two-compartment model. Monte Carlo simulations (MCSs) were performed to observe the probability of target attainment (PTA) when receiving CRRT or not under different dosage regimens, different stratifications of quick C-reactive protein (qCRP), and different minimum inhibitory concentration (MIC) ranges.

RESULTS

A total of 408 critically ill patients with 746 voriconazole concentration-time data points were included in this study. A two-compartment population PK model with qCRP, CRRT, creatinine clearance rate (CLCR), platelets (PLT), and prothrombin time (PT) as fixed effects was developed using the NONMEM.

CONCLUSIONS

We found that qCRP, CRRT, CLCR, PLT, and PT affected the voriconazole clearance. The most commonly used clinical regimen of 200 mg q12h was sufficient for the most common sensitive pathogens (MIC ≤ 0.25 mg/L), regardless of whether CRRT was performed and the level of qCRP. When the MIC was 0.5 mg/L, 200 mg q12h was insufficient only when the qCRP was <40 mg/L and CRRT was performed. When the MIC was ≥2 mg/L, a dose of 300 mg q12h could not achieve ≥ 90% PTA, necessitating the evaluation of a higher dose.

Middle Eastern Expert Opinion: Strategies for Successful Antifungal Stewardship Program Implementation in Invasive Fungal Infections

In recent years, global public health efforts have increasingly emphasized the critical role of antimicrobial stewardship (AMS) in improving outcomes, reducing costs, and combating the growing threat of antimicrobial resistance. However, antifungal stewardship (AFS) has remained relatively overlooked despite the staggering impact of invasive fungal infections (IFIs). This burden is particularly pronounced in hospitals worldwide, with the Middle East facing significant unmet needs. The rising population of immunocompromised individuals vulnerable to IFI has prompted an increased reliance on antifungal agents for both prevention and treatment. Given the considerable mortality associated with IFIs and the emergence of antifungal resistance, implementing AFS programs in hospital settings is becoming increasingly urgent. In this article, we offer expert insights into the strategies that can be used for successful antifungal stewardship program implementation in IFI. Drawing upon the extensive clinical experience of a multinational and multidisciplinary panel, we present recommendations for optimizing AFS practices. We delve into the challenges and practical considerations of tailoring local AFS initiatives to the evolving landscape of fungal infections. Additionally, we provide actionable recommendations and position statements for the effective implementation of AFS programs, informed by the collective clinical experiences of panel members across their respective countries of practice.

Posaconazole versus voriconazole as antifungal prophylaxis for invasive fungal diseases in patients with hematological malignancies

INTRODUCTION

The incidence of invasive fungal diseases (IFDs) has risen in hematologic malignancy patients due to neutropenia. While posaconazole is recommended as the first-line antifungal prophylaxis in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients and voriconazole is an alternative, there is currently no direct comparison data available to assess their relative effectiveness.

METHOD

We retrospectively reviewed eligible patient charts from January 2017 to February 2019 to identify breakthrough IFD rates, drug adverse event frequency, and drug acquisition cost in AML/MDS patients.

RESULTS

Forty-eight patients received 130 chemo cycles, with 50 (38%) cycles prescribed posaconazole and 80 (62%) prescribed voriconazole as primary IFD prophylaxis. The incidence rates of IFD in the posaconazole group were 8% (4 out of 50), of which two were probable and two were possible infections, while 6.26% (5 out of 80) of patients in the voriconazole group developed IFD, with four possible infections and one probable infection (p = 0.73). A higher percentage of patients in the voriconazole group discontinued prophylaxis due to adverse events, with six patients compared to two patients in the posaconazole group (p = 0.15). The drug acquisition cost of posaconazole is 5.62 times more expensive than voriconazole.

CONCLUSION

The use of voriconazole instead of posaconazole for 130 chemo cycles would save $166,584.6. Posaconazole and voriconazole have comparable efficacy and safety in preventing IFD in AML and MDS patients receiving chemotherapy. However, posaconazole is more costly than voriconazole.

Population Pharmacokinetic Modeling of Posaconazole in Japanese Patients Receiving Fungal Prophylaxis

BACKGROUND

Posaconazole is a vital drug to treat and prevent invasive fungal infections. Several factors, such as sex, body weight, total serum proteins, dietary intake, and severe mucositis, affect posaconazole pharmacokinetics (PKs). However, the relevance of other factors that affect the PKs of posaconazole in hematopoietic stem cell transplantation (HSCT) is unknown. This study explored factors influencing the PKs of posaconazole in HSCT recipients and nontransplant patients with hematological diseases.

METHODS

The authors conducted a single-institution, retrospective study. Forty-two Japanese inpatients receiving oral posaconazole tablets as prophylaxis for fungal infections were enrolled in this study. A one-compartment model with first-order absorption was used as the structural pharmacokinetic model. A population PK (PopPK) analysis was performed using a nonlinear mixed-effects modeling program, using a first-order conditional estimation method with interactions. Perl-speaks-NONMEM and R were used to evaluate the goodness of fit and visualize the output.

RESULTS

In 29% of the enrolled patients, the serum concentration of posaconazole was <0.5 mcg/mL, considered the effective range. PopPK analysis revealed that the patient had undergone HSCT within 1 year, diarrhea occurred more than 5 times a day, and aspartate aminotransferase were covariates that influenced apparent clearance (CL/F). The CL/F of posaconazole was 1.43-fold higher after HSCT and 1.26-fold higher during diarrhea.

CONCLUSIONS

PopPK analysis revealed that HSCT, diarrhea, and aspartate aminotransferase were factors associated with the CL/F of posaconazole. The trough concentration of posaconazole may be below the therapeutic range in a few patients with diarrhea and/or after HSCT. As invasive fungal infections in patients with hematologic diseases can be life-threatening, therapeutic drug monitoring of posaconazole is strongly recommended, and patients should be carefully monitored.

Therapeutic drug monitoring of liposomal amphotericin B in children. Are we there yet? A systematic review

INTRODUCTION

Therapeutic drug monitoring (TDM) is a tool that supports personalized dosing, but its role for liposomal amphotericin B (L-amb) is unclear. This systematic review assessed the evidence for L-amb TDM in children.

OBJECTIVES

To evaluate the concentration-efficacy relationship, concentration-toxicity relationship and pharmacokinetic/pharmacodynamic (PK/PD) variability of L-amb in children.

METHODS

We systematically reviewed PubMed and Embase databases following PRISMA guidelines. Eligible studies included L-amb PK/PD studies in children aged 0-18 years. Review articles, case series of

RESULTS

In total, 4220 studies were screened; 6 were included, presenting data on 195 children. Invasive candidiasis and aspergillosis were the two most common infections treated with L-amb. Studies showed significant PK variability due to age (mean age ranged from 14 days to 17 years), body weight, non-linear PK and changes in the volume of distribution. Limited evidence supported a peak concentration/MIC (Cmax/MIC) of 25-50 for optimal efficacy and an AUC24 of >600 mg·h/L for nephrotoxicity. L-amb doses of 2.5-10 mg/kg/day were reported to achieve Cmax/MIC > 25 using an MIC of 1 mg/L.

CONCLUSIONS

While significant PK variability was observed in children, evidence to support routine L-amb TDM was limited. Further studies on efficacy and toxicity benefits are required before routine TDM of L-amb can be recommended.

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MESH Headings

• Humans
• Amphotericin B/pharmacokinetics
• Amphotericin B/administration & dosage
• Amphotericin B/adverse effects
• Amphotericin B/therapeutic use
• Drug Monitoring
• Child
• Antifungal Agents/pharmacokinetics
• Antifungal Agents/administration & dosage
• Antifungal Agents/adverse effects
• Antifungal Agents/therapeutic use
• Child, Preschool
• Adolescent
• Infant
• Infant, Newborn
• Aspergillosis/drug therapy
• Microbial Sensitivity Tests

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Grants

• Australian Government (RTP) Scholarship

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Affiliation(s)

Tony Lai Pharmacy Department, The Children’s Hospital at Westmead, Sydney, NSW, Australia The University of Sydney Infectious Diseases Institute (Sydney ID), Sydney, NSW, Australia Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
Chin-Yen Yeo Pharmacy Department, Concord Hospital, Sydney, Australia
Bradley Rockliff Pharmacy Department, The Children’s Hospital at Westmead, Sydney, NSW, Australia
Michael Stokes Pharmacy Department, The Children’s Hospital at Westmead, Sydney, NSW, Australia The University of Sydney Infectious Diseases Institute (Sydney ID), Sydney, NSW, Australia
Hannah Yejin Kim Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia Pharmacy Department, Westmead Hospital, Sydney, Australia
Ben J Marais The University of Sydney Infectious Diseases Institute (Sydney ID), Sydney, NSW, Australia
Andrew J McLachlan Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
Jan-Willem C Alffenaar The University of Sydney Infectious Diseases Institute (Sydney ID), Sydney, NSW, Australia Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia Pharmacy Department, Westmead Hospital, Sydney, Australia

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Therapeutic drug monitoring of antifungal therapies: do we really need it and what are the best practices?

INTRODUCTION

Despite advancements, invasive fungal infections (IFI) still carry high mortality rates, often exceeding 30%. The challenges in diagnosis, coupled with limited effective antifungal options, make managing IFIs complex. Antifungal drugs are essential for IFI management, but their efficacy can be diminished by drug-drug interactions and pharmacokinetic variability. Therapeutic Drug Monitoring (TDM), especially in the context of triazole use, has emerged as a valuable strategy to optimize antifungal therapy.

AREAS COVERED

This review provides current evidence regarding the potential benefits of TDM in IFI management. It discusses how TDM can enhance treatment response, safety, and address altered pharmacokinetics in specific patient populations.

EXPERT OPINION

TDM plays a crucial role in achieving optimal therapeutic outcomes in IFI management, particularly for certain antifungal agents. Preclinical studies consistently show a link between therapeutic drug levels and antifungal efficacy. However, clinical research in mycology faces challenges due to patient heterogeneity and the diversity of fungal infections. TDM's potential advantages in guiding Echinocandin therapy for critically ill patients warrant further investigation. Additionally, for drugs like Posaconazole, assessing whether serum levels or alternative markers like saliva offer the best measure of efficacy is an intriguing question.

A Prospective Study to Evaluate the Effect of Therapeutic Drug Monitoring-Based Posaconazole Prophylaxis on Invasive Fungal Infection Rate During Acute Myeloid Leukemia Induction Therapy

Invasive fungal infections (IFIs) are a significant cause of morbidity and mortality in de-novo acute myeloid leukemia patients receiving induction chemotherapy. Despite using posaconazole, a broad-spectrum antifungal, for IFI prophylaxis, the breakthrough IFI rate is high in the real-world setting. One of the reasons could be frequent suboptimal plasma posaconazole levels. In the present study, we evaluated if therapeutic drug monitoring (TDM) guided posaconazole prophylaxis can reduce the IFI rates in comparison to a historical cohort. We enrolled 90 patients, > / = 16 years of age, without baseline IFIs, planned for remission induction therapy. All patients were started on posaconazole suspension 200 mg TDS and the dose was increased in a stepwise manner if trough levels were found to be suboptimal (< 350 ng/ml for day 2 or < 700 ng/ml subsequently). The TDM based approach resulted in a significant decline in breakthrough IFI rates (18% versus 52%, P < 0.0001) A total of 69 patients (78%) required dose escalation. Thirty-one patients required change in antifungals due to either suboptimal levels, persistent fever, diarrhoea or vomiting. We could not demonstrate an exposure-response relationship but the difference in IFI rates in patients with a median posaconazole level > / = 700 ng/ml (0%) and < 700 ng/ml (21.6%) was clinically meaningful. Posaconazole levels were found to be significantly lower in patients on antacids and prokinetics. The incidence of posaconazole-related grade 3 toxicity was low (2.3%). Thus TDM-based dosing of posaconazole helps reduce breakthrough IFI rate and should be a part of posaconazole prophylaxis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12288-023-01709-3.

Pharmacotherapeutic Considerations in the Treatment of Nontuberculous Mycobacterial Infections: A Primer for Clinicians

Nontuberculous mycobacteria (NTM) can cause a variety of infections, including serious pulmonary disease. Treatment encompasses polypharmacy, with a targeted regimen of 2-5 active medications, depending on site of infection, species, and clinical characteristics. Medications may include oral, intravenous, and inhalational routes. Medication acquisition can be challenging for numerous reasons, including investigational status, limited distribution models, and insurance prior authorization. Additionally, monitoring and managing adverse reactions and drug interactions is a unique skill set. While NTM is primarily medically managed, clinicians may not be familiar with the intricacies of medication selection, procurement, and monitoring. This review offers insights into the pharmacotherapeutic considerations of this highly complex disease state, including regimen design, medication acquisition, safety monitoring, relevant drug-drug interactions, and adverse drug reactions.

Revised ISHAM-ABPA working group clinical practice guidelines for diagnosing, classifying and treating allergic bronchopulmonary aspergillosis/mycoses

BACKGROUND

The International Society for Human and Animal Mycology (ISHAM) working group proposed recommendations for managing allergic bronchopulmonary aspergillosis (ABPA) a decade ago. There is a need to update these recommendations due to advances in diagnostics and therapeutics.

METHODS

An international expert group was convened to develop guidelines for managing ABPA (caused by Aspergillus spp.) and allergic bronchopulmonary mycosis (ABPM; caused by fungi other than Aspergillus spp.) in adults and children using a modified Delphi method (two online rounds and one in-person meeting). We defined consensus as ≥70% agreement or disagreement. The terms "recommend" and "suggest" are used when the consensus was ≥70% and <70%, respectively.

RESULTS

We recommend screening for A. fumigatus sensitisation using fungus-specific IgE in all newly diagnosed asthmatic adults at tertiary care but only difficult-to-treat asthmatic children. We recommend diagnosing ABPA in those with predisposing conditions or compatible clinico-radiological presentation, with a mandatory demonstration of fungal sensitisation and serum total IgE ≥500 IU·mL-1 and two of the following: fungal-specific IgG, peripheral blood eosinophilia or suggestive imaging. ABPM is considered in those with an ABPA-like presentation but normal A. fumigatus-IgE. Additionally, diagnosing ABPM requires repeated growth of the causative fungus from sputum. We do not routinely recommend treating asymptomatic ABPA patients. We recommend oral prednisolone or itraconazole monotherapy for treating acute ABPA (newly diagnosed or exacerbation), with prednisolone and itraconazole combination only for treating recurrent ABPA exacerbations. We have devised an objective multidimensional criterion to assess treatment response.

CONCLUSION

We have framed consensus guidelines for diagnosing, classifying and treating ABPA/M for patient care and research.

Factors influencing voriconazole plasma level in intensive care patients

Background

In clinical routine, voriconazole plasma trough levels (Cmin) out of target range are often observed with little knowledge about predisposing influences.

Objectives

To determine the distribution and influencing factors on voriconazole blood levels of patients treated on intensive- or intermediate care units (ICU/IMC).

Patients and methods

Data were collected retrospectively from patients with at least one voriconazole trough plasma level on ICU/IMC (n = 153) to determine the proportion of sub-, supra- or therapeutic plasma levels. Ordinal logistic regression analysis was used to assess factors hindering patients to reach voriconazole target range.

Results

Of 153 patients, only 71 (46%) reached the target range at the first therapeutic drug monitoring, whereas 66 (43%) patients experienced too-low and 16 (10%) too-high plasma levels. Ordinal logistic regression analysis identified the use of extra corporeal membrane oxygenation (ECMO), low international normalized ratio (INR) and aspartate-aminotransferase (AST) serum levels as predictors for too-low plasma levels.

Conclusion

Our data highlight an association of ECMO, INR and AST levels with voriconazole plasma levels, which should be considered in the care of critically ill patients to optimize antifungal therapy with voriconazole.

Navigating fungal infections and antifungal stewardship: drug resistance, susceptibility testing, therapeutic drug monitoring and future directions

Antifungal stewardship refers to the rational use of antifungal agents. Historically, in some instances, the misuse or overuse of antifungal agents has predisposed patients to an elevated risk of systemic side-effects and treatment resistance, as well as increased healthcare costs. Superficial mycoses, such as onychomycosis, are sometimes treated without any diagnostic testing and is associated with a high likelihood of self-diagnosis and self-treatment, potentially leading to the emergence of resistance against commonly used antifungals like terbinafine. Practitioners need to ensure that a proper clinical diagnosis is backed up by appropriate testing. This may include the traditional light microscopy and culture; additionally, molecular techniques (such as polymerase chain reaction, terbinafine gene mutational analysis) and antifungal susceptibility testing are considerations as appropriate. The choice of antifungal agent should be guided by what is the standard of care in the location where the clinician practices as well as more broadly state and national prescription patterns. Recently, reports of treatment resistance concerning both superficial and deep fungal infections have added another layer of difficulty to clinical practice. This review aims to explore the phenomenon of antifungal drug resistance, and highlights the importance of adopting antifungal stewardship programs. We provide an overview of treatment resistance and mechanisms of resistance reported thus far in dermatophytes. Challenges of performing antifungal susceptibility testing and therapeutic drug monitoring are discussed, as well as principles, recommendations and future directions of antifungal stewardship programs.

The cost-utility analysis of antifungal prophylaxis for invasive fungal infections in acute myeloid leukaemia patients receiving chemotherapy: a study from a middle-income country

BACKGROUND

Invasive fungal infections (IFIs) contribute to morbidity and mortality during acute myeloid leukaemia (AML) treatment. Without prophylaxis, IFI rate during AML treatment in Thailand is high and results in a high mortality rate and a prolonged hospital stay.

AIM

To evaluate the cost-utility of antifungal therapy (AFT) prophylaxis during AML treatment.

METHODS

We assessed the cost-utility of AFT available in Thailand, including posaconazole (solution), itraconazole (solution and capsule), and voriconazole. A hybrid model consisting of a decision tree and the Markov model was established.

RESULTS

The costs to prevent overall IFI using any AFT were all lower than the treatment cost of a non-prophylaxis group, resulting in a saving of 808-1507 USD per patient. Prevention with voriconazole prophylaxis showed the highest quality-adjusted life years (QALYs = 3.51, incremental QALYs = 0.23), followed by posaconazole (QALYs = 3.46, incremental QALY = 0.18) and itraconazole solution (QALYs = 3.45, incremental QALYs = 0.17). Itraconazole capsule reduced QALY in the model. For invasive aspergillosis prevention, posaconazole and voriconazole both resulted in better QALYs and life year savings compared with no prophylaxis. However, posaconazole prophylaxis was the only cost-saving option (976 USD per patient).

CONCLUSION

Posaconazole, itraconazole solution and voriconazole were all cost saving compared with no prophylaxis for overall IFI prophylaxis, with voriconazole being the most cost-effective option. Posaconazole and voriconazole were both cost effective for invasive aspergillosis prevention but only posaconazole was cost saving. A change in reimbursement policy for the use of AFT prophylaxis during intensive AML treatment could provide both clinical benefits to patients and substantial economic benefits to healthcare systems.

Supratherapeutic posaconazole concentrations associated with hyperlipidemia in a patient with HSCT

Posaconazole is a potent, extended-spectrum triazole antifungal used for the treatment and prophylaxis of serious fungal infections. Previous reports have demonstrated hyperlipidemia resulted in significant changes in posaconazole pharmacokinetics and tissue distribution in rats. However, the effect of hyperlipidemia on the pharmacokinetics of posaconazole in patients has not yet been reported. We report a case of a 34-year-old woman who experienced a supratherapeutic posaconazole trough concentration (PTC) associated with hyperlipidemia after haploidentical hematopoietic stem cell transplantation (HSCT). The patient was admitted 13 months after HSCT for recurrent cough and sputum. She was treated with caspofungin due to developing invasive fungal infection of Candida tropicalis. After 10 days, caspofungin was discontinued due to the poor therapeutic efficacy and replaced with amphotericin B. Afterwards, the condition of the patient improved significantly and she was switched to daily oral posaconazole tablet. Therapeutic drug monitoring (TDM) of posaconazole showed a PTC was 3.2 mg/L. After discharge, she continued to receive posaconazole tablet as antifungal treatment. Two months later, laboratory tests at outpatient showed her blood lipid levels were significantly elevated and PTC was increased to 9.38 mg/L. Therefore, the posaconazole tablet was discontinued and she received lipid-lowering therapy. A few days later, the PTC was down to 5.22 mg/L. No medication errors and significant drug interactions were found. Hence, supratherapeutic PTC for this patient may be caused by hyperlipidemia which altered pharmacokinetics of posaconazole. Our findings highlight the need for close TDM in order to avoid supratherapeutic PTC if hyperlipidimia occurs during posaconazole use.

Impact of Anti-Mycotic Drugs on the Osteogenic Response of Bone Marrow Mesenchymal Stem Cells In Vitro

The treatment of fungal bone infections and infected non-unions is a huge challenge in modern trauma and orthopedics, which normally contain the local and systemic administration of anti-fungal drugs. Although frequently used, little is known about the impact of systemic and locally administered fungicides on the osteogenic regenerative capabilities of infected bone tissue, especially upon the osteogenesis of human bone marrow mesenchymal stem cells (BM-hMSCs). This study evaluates the effects of the three most common fungicides for the systemic treatment of bone infections, Voriconazole (VOR), liposomal Amphotericin B (LAMB), and Fluconazole (FLU), as well as the effects of VOR and LAMB-loaded Polymethylmethacrylate (PMMA) cement chips in different concentrations upon the osteogenic response of BM-hMSCs in vitro. Within this study, we compared the ability of BM-hMSC to differentiate into osteoblast-like cells and synthesize hydroxyapatite as assessed by radioactive 99mTechnetium-Hydroxydiphosphonate (99mTc-HDP) labeling, cell proliferation, and analyses of supernatants upon various osteogenic parameters. Our results revealed that VOR added to the cell culture medium affects the osteogenic potential of BM-hMSC negatively, while there were no detectable effects of LAMB and FLU. Moreover, we showed dose-dependent negative effects of high- and extended-dose fungicide-loaded PMMA cement due to cytotoxicity, with a higher cytotoxic potential of VOR than LAMB, while low-dose fungicide-loaded PMMA had no significant effect on the osteogenic potential of BM-hMSC in vitro.

Histoplasmosis in Solid Organ Transplantation

Histoplasma capsulatum, the etiological agent for histoplasmosis, is a dimorphic fungus that grows as a mold in the environment and as a yeast in human tissues. It has a broad global distribution with shifting epidemiology during recent decades. While in immunocompetent individuals infection is usually self-resolving, solid organ transplant recipients are at increased risk of symptomatic disease with dissemination to extrapulmonary tissue. Diagnosis of histoplasmosis relies on direct observation of the pathogen (histopathology, cytopathology, and culture) or detection of antigens, antibodies, or nucleic acids. All transplant recipients with histoplasmosis warrant therapy, though the agent of choice and duration of therapy depends on the severity of disease. In the present article, we describe the pathogenesis, epidemiology, clinical manifestations and management of histoplasmosis in solid organ transplant recipients.

The impact of extracorporeal membrane oxygenation on antifungal pharmacokinetics: A systematic review

BACKGROUND AND OBJECTIVE

The use of extracorporeal membrane oxygenation (ECMO) as a cardiocirculatory or respiratory support has tremendously increased in critically ill patients. In the setting of ECMO support, invasive fungal infections are a severe cause of morbidity and mortality. This vulnerable population is at risk of suboptimal antifungal exposure due to an increased volume of distribution (Vd), drug sequestration and decreased clearance. Here, we aimed to summarize ex-vivo and clinical studies on the potential impact of ECMO on the pharmacokinetics (PK) of antifungal agents and dosing requirements.

METHODS

A systematic search of the literature within electronic databases PubMed and EMBASE was conducted from database inception to 30 April 2023. Inclusion criteria were as follows: critically ill patients receiving ECMO regardless of age and reporting at least one PK parameter.

RESULTS

Thirty-six studies met inclusion criteria, including seven ex-vivo experiments and 29 clinical studies evaluating three classes of antifungals: polyenes, triazoles and echinocandins. Based on the available ex-vivo PK data, we found a significant sequestration of highly lipophilic and protein-bound antifungals within the ECMO circuit such as voriconazole, posaconazole and micafungin but the PK of several antifungals remains to be addressed such as amphotericin B, isavuconazole and anidulafungin. Most clinical studies have shown increased Vd of some antifungals like fluconazole and micafungin, particularly in the pediatric population. Conflicting data exist about caspofungin exposure.

CONCLUSIONS

The available literature on the antifungal PK changes in ECMO setting is scarce. Whenever possible, therapeutic drug monitoring is highly advised to personalize antifungal therapy.

Therapeutic Drug Monitoring of Voriconazole in Patients with End-Stage Liver Disease

BACKGROUND

This study aimed to identify the factors that influence voriconazole (VCZ) plasma concentrations and optimize the doses of VCZ in patients with end-stage liver disease (ESLD).

METHODS

Patients with ESLD who received a VCZ maintenance dose of 100 mg twice daily (group A, n = 57) or the VCZ maintenance dose of 50 mg twice daily (group B, n = 37), orally or intravenously, were enrolled in this study. Trough plasma concentrations (Cmin) of VCZ between 1 and 5 mg/L were considered within the therapeutic target range.

RESULTS

The VCZ Cmin was determined in 94 patients with ESLD. The VCZ Cmin of patients in group A was remarkably higher than those in group B (4.85 ± 2.53 mg/L vs 2.75 ± 1.40 mg/L; P < 0.001). Compared with group A, fewer patients in group B had VCZ Cmin outside the therapeutic target (23/57 vs. 6/37, P = 0.021). Univariate and multivariate analyses suggested that both body weight and Model for End-Stage Liver Disease scores were closely associated with the VCZ Cmin in group B.

CONCLUSIONS

These data indicate that dose optimization based on body weight and Model for End-Stage Liver Disease scores is required to strike an efficacy-safety balance during VCZ treatment in patients with ESLD.

Laboratory and clinical management capacity for invasive fungal infections: the Italian landscape

BACKGROUND

We assessed the laboratory diagnosis and treatment of invasive fungal disease (IFD) in Italy to detect limitations and potential for improvement.

METHODS

The survey was available online at www.clinicalsurveys.net/uc/IFI management capacity/, and collected variables such as (a) institution profile, (b) perceptions of IFD in the respective institution, (c) microscopy, (d) culture and fungal identification, (e) serology, (f) antigen detection, (g) molecular tests, (h) susceptibility testing and (i) therapeutic drug monitoring (TDM).

RESULTS

The laboratory capacity study received responses from 49 Italian centres, with an equitable geographical distribution of locations. The majority of respondents (n = 36, 73%) assessed the occurrence of IFD as moderate-high, with Aspergillus spp. being the pathogen of highest concern, followed by Candida spp. and Mucorales. Although 46 (94%) of the institutions had access to microscopy, less than half of them performed direct microscopy on clinical specimens always when IFD was suspected. Cultures were available in all assessed laboratories, while molecular testing and serology were available in 41 (83%), each. Antigen detection tests and antifungal drugs were also generally accessible (> 90%) among the participating institutions. Nevertheless, access to TDM was limited (n = 31, 63%), with a significant association established between therapeutic drug monitoring availability and higher gross domestic product per capita.

CONCLUSIONS

Apart from TDM, Italy is adequately prepared for the diagnosis and treatment of IFD, with no significant disparities depending on gross domestic product. Future efforts may need to focus on enhancing the availability and application of direct microscopic methods, as well as TDM, to promote optimal treatment and better patient outcomes.

Antifungal Resistance in Cryptococcal Infections

Antifungal therapy, especially with the azoles, could promote the incidence of less susceptible isolates of Cryptococcus neoformans and C. gattii species complexes (SC), mostly in developing countries. Given that these species affect mostly the immunocompromised host, the infections are severe and difficult to treat. This review encompasses the following topics: 1. infecting species and their virulence, 2. treatment, 3. antifungal susceptibility methods and available categorical endpoints, 4. genetic mechanisms of resistance, 5. clinical resistance, 6. fluconazole minimal inhibitory concentrations (MICs), clinical outcome, 7. environmental influences, and 8. the relevance of host factors, including pharmacokinetic/pharmacodynamic (PK/PD) parameters, in predicting the clinical outcome to therapy. As of now, epidemiologic cutoff endpoints (ECVs/ECOFFs) are the most reliable antifungal resistance detectors for these species, as only one clinical breakpoint (amphotericin B and C. neoformans VNI) is available.

Enhancing the identification of voriconazole-associated hepatotoxicity by targeted metabolomics

Voriconazole-associated hepatotoxicity is a common condition that generally manifests as elevated liver enzymes and can lead to drug discontinuation. Careful monitoring of voriconazole-associated hepatotoxicity is needed but there are no specific plasma biomarkers for this condition. Metabolomics has emerged as a promising technique for investigating biomarkers associated with drug-induced toxicity. The aim of this study was to use targeted metabolomics to evaluate seven endogenous metabolites as potential biomarkers of voriconazole-associated hepatotoxicity. Patients undergoing therapeutic drug monitoring of voriconazole were classified into a hepatotoxicity group (18 patients) or a control group (153 patients). Plasma samples were analysed using ultra-high-performance liquid chromatography coupled to mass spectrometry. Metabolite concentrations in the two groups were compared. Areas under the receiver operating characteristic (AUROC) curves generated from logistic regressions were used to correlate the concentrations of these seven metabolites with voriconazole trough concentrations and conventional liver biochemistry tests. Glycocholate and α-ketoglutarate levels were significantly higher in the hepatotoxicity group compared with the control group (false discovery rate-corrected P < 0.001 and P = 0.024, respectively). The metabolites glycocholate (AUROC = 0.795) and α-ketoglutarate (AUROC = 0.696) outperformed voriconazole trough concentrations (AUROC = 0.555) and approached the performance of alkaline phosphatase (AUROC = 0.876) and total bilirubin (AUROC = 0.815). A panel of glycocholate combined with voriconazole trough concentrations (AUROC = 0.827) substantially improved the performance of voriconazole trough concentrations alone in predicting hepatotoxicity. In conclusion, the panel integrating glycocholate with voriconazole trough concentrations has great potential for identifying voriconazole-associated hepatotoxicity.

Optimized Antifungal Therapy for Chronic Pulmonary Aspergillosis

Chronic pulmonary aspergillosis (CPA) represents a spectrum of lung disorders caused by local proliferation of Aspergillus hyphae in individuals with non-systemic or mildly systemic immunodepression or altered pulmonary integrity due to underlying disease. While long-term systemic antifungal treatment is still the mainstay for management, surgery is considered mainly in rarer invasive disease manifestations such as sinusitis and osteomyelitis. Optimal application of existing antifungal agents with suitable pharmacokinetic properties is important for the treatment of diseases such as CPA, which requires long-term use. Appropriate management of side effects by therapeutic drug monitoring, maintenance of adherence, and assessment of drug resistance to Aspergillus can provide safe and effective treatment in the future. Most available antifungal agents for the management of mycoses in humans have disadvantages that can limit their use in clinical practice. By contrast, second generation antifungals such as triazoles have advantages of extended antifungal spectrum and availability in both oral and intravenous formulations. Isavuconazole, a new extended spectrum triazole, has been shown to be effective against Aspergillus. The safety profile and excellent pharmacokinetic characteristics of isavuconazole make it an attractive option for treatment of invasive fungal infections including CPA. With this drug now available in Japan, new evidence is expected to expand treatment options. This review focuses on the selection of antifungal agents based on national and international guidelines and the characteristics of each agent for their appropriate use in CPA.

Chronic pulmonary aspergillosis - a guide for the general physician

This collaborative article presents a review of chronic pulmonary aspergillosis (CPA) from the perspective of a multidisciplinary team comprising of respiratory physicians, radiologists, mycologists, dietitians, pharmacists, physiotherapists and palliative care specialists. The review synthesises current knowledge on CPA, emphasising the intricate interplay between clinical, radiological, and microbiological aspects. We highlight the importance of assessing each patient as multidisciplinary team to ensure personalised treatment strategies and a holistic approach to patient care.

Triazole Antifungal Quantification for Therapeutic Drug Monitoring in Serum by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS): Posaconazole, Voriconazole, Itraconazole, and Hydroxyitraconazole

Antifungal therapy with triazole drugs including posaconazole, voriconazole, itraconazole, and its active metabolite hydroxyitraconazole is routinely accompanied by therapeutic drug monitoring to ensure optimal dosing. The method presented here simultaneously quantitates these compounds in serum by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Specimen preparation includes protein precipitation with a methanol and acetonitrile mixture, centrifugation, and filtration. Analyte separation is achieved by reverse-phase chromatography using a dC18 column and a linear gradient of methanol in water. Analytes are detected by multiple reaction monitoring mass spectrometry and quantitated by comparison to a standard curve.

Diagnosis and management of cryptococcal meningitis in HIV-infected adults

Cryptococcal meningitis is a leading cause of morbidity and mortality globally, especially in people with advanced HIV disease. Cryptococcal meningitis is responsible for nearly 20% of all deaths related to advanced HIV disease, with the burden of disease predominantly experienced by people in resource-limited countries. Major advancements in diagnostics have introduced low-cost, easy-to-use antigen tests with remarkably high sensitivity and specificity. These tests have led to improved diagnostic accuracy and are essential for screening campaigns to reduce the burden of cryptococcosis. In the last 5 years, several high-quality, multisite clinical trials have led to innovations in therapeutics that have allowed for simplified regimens, which are better tolerated and result in less intensive monitoring and management of medication adverse effects. One trial found that a shorter, 7-day course of deoxycholate amphotericin B is as effective as the longer 14-day course and that flucytosine is an essential partner drug for reducing mortality in the acute phase of disease. Single-dose liposomal amphotericin B has also been found to be as effective as a 7-day course of deoxycholate amphotericin B. These findings have allowed for simpler and safer treatment regimens that also reduce the burden on the healthcare system. This review provides a detailed discussion of the latest evidence guiding the clinical management and special circumstances that make cryptococcal meningitis uniquely difficult to treat.

Comparison of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and enzyme-multiplied immunoassay technique (EMIT) for quantification of voriconazole plasma concentration from Chinese patients

Introduction

Voriconazole (VRZ) is the recommended standard treatment for life-threatening invasive aspergillosis. The plasma concentration of VRZ should be determined to optimise treatment results and reduce side effects. This study aimed to compare the correlation and concordance of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and enzyme-multiplied immunoassay technique (EMIT) to determine VRZ plasma concentration in clinical practice.

Methods

An isotopically labelled internal standard UPLC-MS/MS method was established, validated, and subsequently applied to determine VRZ concentration. The UPLC-MS/MS method was also compared with a commercial EMIT method regarding results correlation and concordance.

Results

The calibration curve of UPLC-MS/MS was linear from 0.1 to 10 mg/L, the inter- and intra-day relative standard deviations (RSDs), and the stability of quality control samples were less than 15 %, satisfying the Bioanalytical Method Validation Guidelines. A total of 122 plasma samples were collected and analyzed using both methods. UPLC-MS/MS and EMIT showed a high correlation (r = 0.9534), and Bland-Altman analysis indicated a mean absolute bias of 1.035 mg/L and an average bias of 27.56 % between UPLC-MS/MS and EMIT. The paired Wilcoxon test and Bland-Altman analysis revealed poor consistency between the two methods. Furthermore, we compared the effects of different methods in clinical applications. Two threshold values for treatment efficacy (1.0 mg/L) and safety (5.5 mg/L) were established, and considerable discordance was observed between the original EMIT and UPLC-MS/MS results at both thresholds (p < 0.05). Nevertheless, the adjusted EMIT results were not inconsistent with the UPLC-MS/MS results regarding the efficacy (p = 0.125) and safety (p = 1.0) thresholds.

Conclusions

The isotopically labelled internal standard UPLC-MS/MS method is established and well applied in the clinical setting. A strong correlation but discordance was found between UPLC-MS/MS and EMIT, indicating that switching from UPLC-MS/MS to EMIT was unsuitable. However, the adjusted EMIT results may serve as a reliable surrogate when UPLC-MS/MS results cannot be obtained when necessary.

Therapeutic drug monitoring in India: A strength, weakness, opportunity and threats analysis

Over the last three to four decades, Therapeutic Drug Monitoring (TDM) has shaped itself as therapeutic drug management, an integral component of precision medicine. The practice of TDM is not extensive in India, despite being one of the fastest-growing economies in the world. It is currently limited to a few academic medical centres and teaching hospitals. Apart from the immunosuppressive drugs, several other therapeutic areas, such as anticancer, antifungal, antibiotic and antitubercular, have demonstrated great potential to improve patient outcomes in Indian settings. Factors such as the higher prevalence of nutritional deficiencies, tropical diseases, widespread use of alternative medicines, unalike pharmacogenomics and sparse population-specific data available on therapeutic ranges of several drugs make the population of this subcontinent unique regarding the relevance of TDM. Despite the impact of TDM in clinical science and its widespread application, TDM has failed to receive the attention it deserves in India. This review intends to bring out a strength, weakness, opportunity and threats (SWOT) analysis for TDM in India so that appropriate steps for fostering the growth of TDM could be envisioned. The need of the hour is the creation of a cooperative group including all the stakeholders, such as TDM professionals, clinicians and the government and devising a National Action Plan to strengthen TDM. Nodal TDM centres should be established, and pilot programmes should be rolled out to identify the thrust areas for TDM in the country, capacity building and creating awareness to integrate TDM into mainstream clinical medicine.

Coccidioidomycosis Osteoarticular Dissemination

Valley fever or coccidioidomycosis is a pulmonary infection caused by species of Coccidioides fungi that are endemic to California and Arizona. Skeletal coccidioidomycosis accounts for about half of disseminated infections, with the vertebral spine being the preferred site of dissemination. Most cases of skeletal coccidioidomycosis progress to bone destruction or spread to adjacent structures such as joints, tendons, and other soft tissues, causing significant pain and restricting mobility. Manifestations of such cases are usually nonspecific, making diagnosis very challenging, especially in non-endemic areas. The lack of basic knowledge and research data on the mechanisms defining susceptibility to extrapulmonary infection, especially when it involves bones and joints, prompted us to survey available clinical and animal data to establish specific research questions that remain to be investigated. In this review, we explore published literature reviews, case reports, and case series on the dissemination of coccidioidomycosis to bones and/or joints. We highlight key differential features with other conditions and opportunities for mechanistic and basic research studies that can help develop novel diagnostic, prognostic, and treatment strategies.

Itraconazole Serum Trough Concentrations Using Oral Capsules for the Treatment of Chronic Pulmonary Aspergillosis: What is the Target?

BACKGROUND

In regions where there is only itraconazole capsule as a therapeutic option for treatment of chronic pulmonary aspergillosis (CPA), measuring the serum concentrations becomes even more important for therapeutic success.

OBJECTIVE

Evaluate the initial itraconazole serum trough concentrations after the administration of oral capsule of itraconazole for the treatment of CPA.

METHODS

The measurement was performed at least 7-days after initiation of therapy. The standard treatment at our institution was a 200 mg capsule every 12 h. We defined that an adequate serum trough concentration of itraconazole during treatment was 1-4 mg/L.

RESULTS

This study recruited 28 patients. The median value was 0.30 mg/L (IQR 0.01-0.70). Only 11% (n = 3) had adequate serum concentrations based on guideline recommendation. All patients with clinical deterioration had itraconazole serum levels ≤ 0.8 mg/L.

CONCLUSION

The initial serum concentrations of itraconazole after capsule formulation administration were low. Increasing the dose should be considered when the itraconazole concentration is low, especially if it is ≤ 0.8 mg/L, and the patient presents with clinical deterioration. Larger studies are needed to evaluate the adequate concentrations recommended for CPA.

Posaconazole and midostaurin in patients with FLT3-mutated acute myeloid leukemia: Pharmacokinetic interactions and clinical facts in a real life study

Midostaurin is used in combination with chemotherapy to treat patients with newly diagnosed FLT3-mutated acute myeloid leukemia. Chemotherapy-induced neutropenia exposes these patients to a significant risk of invasive fungal infections (IFIs). International guidelines recommend primary antifungal prophylaxis with posaconazole (PCZ) but nested analysis of a phase III trial showed that strong PCZ inhibition of CYP3A4 diminished midostaurin metabolism and increased midostaurin plasma levels; however, midostaurin-related adverse events (AEs) were only moderately exacerbated. We conducted a prospective multicenter real-life study to evaluate (i) how often concerns around PCZ-midostaurin interactions made the hematologist prescribe antifungals other than PCZ, (ii) how remarkably PCZ increased midostaurin plasma levels, and (iii) how significantly PCZ-midostaurin interactions influenced hematologic and safety outcomes of induction therapy. Although the hematologists were blinded to pharmacokinetic findings, as many as 16 of 35 evaluable patients were prescribed antifungal prophylaxis with micafungin, weak CYP3A4 inhibitor, in place of PCZ (p < 0.001 for deviation from guidelines). In the 19 patients managed as per guidelines, PCZ-midostaurin interactions were more remarkable than previously characterized, such that at the end of induction therapy midostaurin minimum plasma concentration (Cmin ) was greater than three times higher than reported; moreover, midostaurin Cmin , maximum plasma concentration, and area under the curve were more than or equal to four times higher with PCZ than micafungin. Hematologic outcomes (complete remission and duration of severe neutropenia) and safety outcomes (midostaurin-related any grade or grade ≥3 AEs) were nonetheless similar for patients exposed to PCZ or micafungin, as was the number of breakthrough IFIs. In waiting for randomized phase III trials of new prophylaxis regimens, these findings show that PCZ should remain the antifungal of choice for the midostaurin-treated patient.

Towards Model-Informed Precision Dosing of Voriconazole: Challenging Published Voriconazole Nonlinear Mixed-Effects Models with Real-World Clinical Data

BACKGROUND AND OBJECTIVES

Model-informed precision dosing (MIPD) frequently uses nonlinear mixed-effects (NLME) models to predict and optimize therapy outcomes based on patient characteristics and therapeutic drug monitoring data. MIPD is indicated for compounds with narrow therapeutic range and complex pharmacokinetics (PK), such as voriconazole, a broad-spectrum antifungal drug for prevention and treatment of invasive fungal infections. To provide guidance and recommendations for evidence-based application of MIPD for voriconazole, this work aimed to (i) externally evaluate and compare the predictive performance of a published so-called 'hybrid' model for MIPD (an aggregate model comprising features and prior information from six previously published NLME models) versus two 'standard' NLME models of voriconazole, and (ii) investigate strategies and illustrate the clinical impact of Bayesian forecasting for voriconazole.

METHODS

A workflow for external evaluation and application of MIPD for voriconazole was implemented. Published voriconazole NLME models were externally evaluated using a comprehensive in-house clinical database comprising nine voriconazole studies and prediction-/simulation-based diagnostics. The NLME models were applied using different Bayesian forecasting strategies to assess the influence of prior observations on model predictivity.

RESULTS

The overall best predictive performance was obtained using the aggregate model. However, all NLME models showed only modest predictive performance, suggesting that (i) important PK processes were not sufficiently implemented in the structural submodels, (ii) sources of interindividual variability were not entirely captured, and (iii) interoccasion variability was not adequately accounted for. Predictive performance substantially improved by including the most recent voriconazole observations in MIPD.

CONCLUSION

Our results highlight the potential clinical impact of MIPD for voriconazole and indicate the need for a comprehensive (pre-)clinical database as basis for model development and careful external model evaluation for compounds with complex PK before their successful use in MIPD.

Novel Approaches to Characterize Individual Drug Metabolism and Advance Precision Medicine

Interindividual variability in drug metabolism can significantly affect drug concentrations in the body and subsequent drug response. Understanding an individual's drug metabolism capacity is important for predicting drug exposure and developing precision medicine strategies. The goal of precision medicine is to individualize drug treatment for patients to maximize efficacy and minimize drug toxicity. While advances in pharmacogenomics have improved our understanding of how genetic variations in drug-metabolizing enzymes (DMEs) affect drug response, nongenetic factors are also known to influence drug metabolism phenotypes. This minireview discusses approaches beyond pharmacogenetic testing to phenotype DMEs-particularly the cytochrome P450 enzymes-in clinical settings. Several phenotyping approaches have been proposed: traditional approaches include phenotyping with exogenous probe substrates and the use of endogenous biomarkers; newer approaches include evaluating circulating noncoding RNAs and liquid biopsy-derived markers relevant to DME expression and function. The goals of this minireview are to 1) provide a high-level overview of traditional and novel approaches to phenotype individual drug metabolism capacity, 2) describe how these approaches are being applied or can be applied to pharmacokinetic studies, and 3) discuss perspectives on future opportunities to advance precision medicine in diverse populations. SIGNIFICANCE STATEMENT: This minireview provides an overview of recent advances in approaches to characterize individual drug metabolism phenotypes in clinical settings. It highlights the integration of existing pharmacokinetic biomarkers with novel approaches; also discussed are current challenges and existing knowledge gaps. The article concludes with perspectives on the future deployment of a liquid biopsy-informed physiologically based pharmacokinetic strategy for patient characterization and precision dosing.

Utility of triazole antifungal therapeutic drug monitoring: Insights from the Society of Infectious Diseases Pharmacists: Endorsed by the Mycoses Study Group Education and Research Consortium

Triazole antifungals (i.e., fluconazole, itraconazole, voriconazole, posaconazole, and isavuconazole) are commonly used in clinical practice to prevent or treat invasive fungal infections. Most triazole antifungals require therapeutic drug monitoring (TDM) due to highly variable pharmacokinetics, known drug interactions, and established relationships between exposure and response. On behalf of the Society of Infectious Diseases Pharmacists (SIDP), this insight describes the pharmacokinetic principles and pharmacodynamic targets of commonly used triazole antifungals and provides the rationale for utility of TDM within each agent.

Population pharmacokinetics of voriconazole and the role of CYP2C19 genotype on treatment optimization in pediatric patients

The aim of this study was to evaluate factors that impact on voriconazole (VRC) population pharmacokinetic (PPK) parameters and explore the optimal dosing regimen for different CYP2C19 genotypes in Chinese paediatric patients. PPK analysis was used to identify the factors contributing to the variability in VRC plasma trough concentrations. A total of 210 VRC trough concentrations from 91 paediatric patients were included in the study. The median VRC trough concentration was 1.23 mg/L (range, 0.02 to 8.58 mg/L). At the measurement of all the trough concentrations, the target range (1.0~5.5 mg/L) was achieved in 52.9% of the patients, while subtherapeutic and supratherapeutic concentrations were obtained in 40.9% and 6.2% of patients, respectively. VRC trough concentrations were adjusted for dose (Ctrough/D), with normal metabolizers (NMs) and intermediate metabolizers (IMs) having significantly lower levels than poor metabolizers (PMs) (PN-P < 0.001, PI-P = 0.039). A one-compartment model with first-order absorption and elimination was suitable to describe the VRC pharmacokinetic characteristics. The final model of VRC PPK analysis contained CYP2C19 phenotype as a significant covariate for clearance. Dose simulations suggested that a maintenance dose of 9 mg/kg orally or 8 mg/kg intravenously twice daily was appropriate for NMs to achieve the target concentration. A maintenance dose of 9 mg/kg orally or 5 mg/kg intravenously twice daily was appropriate for IMs. Meanwhile, PMs could use lower maintenance dose and an oral dose of 6 mg/kg twice daily or an intravenous dose of 5mg/kg twice daily was appropriate. To increase the probability of achieving the therapeutic range and improving efficacy, CYP2C19 phenotype can be used to predict VRC trough concentrations and guide dose adjustments in Chinese pediatric patients.