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

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.

Voriconazole Use in Children: Therapeutic Drug Monitoring and Control of Inflammation as Key Points for Optimal Treatment

Voriconazole plasma concentrations (PC) are highly variable, particularly in children. Dose recommendations in 2-12-year-old patients changed in 2012. Little data on therapeutic drug monitoring (TDM) after these new recommendations are available. We aimed to evaluate voriconazole monitoring in children with invasive fungal infection (IFI) after implementation of new dosages and its relationship with safety and effectiveness. A prospective, observational study, including children aged 2-12 years, was conducted. TDM was performed weekly and doses were changed according to an in-house protocol. Effectiveness, adverse events, and factors influencing PC were analysed. A total of 229 PC from 28 IFI episodes were obtained. New dosing led to a higher rate of adequate PC compared to previous studies; still, 35.8% were outside the therapeutic range. In patients aged < 8 years, doses to achieve therapeutic levels were higher than recommended. Severe hypoalbuminemia and markedly elevated C-reactive protein were related to inadequate PC. Therapeutic PC were associated with drug effectiveness and safety. Higher doses in younger patients and a dose adjustment protocol based on TDM should be considered. Voriconazole PC variability has decreased with current updated recommendations, but it remains high and is influenced by inflammatory status. Additional efforts to control inflammation in children with IFI should be encouraged.

Blastomycosis

Blastomycosis is the fungal disease caused by thermally dimorphic fungi in the genus Blastomyces, with B dermatitidis complex causing most cases. It is considered hyperendemic in areas adjacent to the Great Lakes and along the St. Lawrence, Mississippi, and Ohio rivers, but definitive geographic distribution of blastomycoses remains obscure. Clinical presentation is variable. Disseminated blastomycosis with extrapulmonary manifestations is more common in immunosuppressed individuals. Culture positivity is required for definitive diagnosis, but compatible histology is often sufficient for presumptive diagnosis and initiation of treatment. Treatment should be provided to all symptomatic cases to prevent progression or recurrence.

Aspergillosis: Epidemiology, Diagnosis, and Treatment

The spectrum of disease produced by Aspergillus species ranges from allergic syndromes to chronic pulmonary conditions and invasive infections. Invasive aspergillosis is a major cause of morbidity and mortality in immunocompromised patients. Risk factors continue to evolve and include newer biological agents that target the immune system and postinfluenza infection; and it has been observed following COVID-19 infection. Diagnosis remains a challenge but non-culture-based methods are available. Antifungal resistance has emerged. Voriconazole remains the treatment of choice but isavuconazole and posaconazole have similar efficacy with less toxicity. Combination therapy is used with extensive infection and in severe immunosuppression.

Interactive Effects of Glucocorticoids and Cytochrome P450 Polymorphisms on the Plasma Trough Concentrations of Voriconazole

Aims: To explore the interactive influence of glucocorticoids and cytochrome P450 (CYP450) polymorphisms on voriconazole (VRC) plasma trough concentrations (C_min) and provide a reliable basis for reasonable application of VRC.

Methods: A total of 918 VRC C_min from 231 patients was collected and quantified using high-performance liquid chromatography in this study. The genotypes of CYP2C19, CYP3A4, and CYP3A5 were detected by DNA sequencing assay. The effects of different genotypes and the coadministration of glucocorticoids on VRC C_min were investigated. Furthermore, the interactive effects of glucocorticoids with CYP450s on VRC C_min were also analyzed.

Results: The median C_min of oral administration was lower than that of intravenous administration (1.51 vs. 4.0 mg l⁻¹). Coadministration of glucocorticoids (including dexamethasone, prednisone, prednisolone, and methylprednisolone) reduced the VRC C_min/dose, respectively, among which dexamethasone make the median of the VRC C_min/dose ratio lower. As a result, when VRC was coadministrated with glucocorticoids, the proportion of VRC C_min/dose in the subtherapeutic window was increased. Different CYP450 genotypes have different effects on the C_min/dose of VRC. Mutations of CYP2C19*2 and *3 increased C_min/dose of VRC, while CYP2C19*17 and CYP3A4 rs4646437 polymorphisms decreased C_min/dose of VRC. The mutation of CYP3A5 has no significant effect. Furthermore, CYP2C19*17 mutants could strengthen the effects of glucocorticoids and decrease VRC C_min/dose to a larger extent.

Conclusion: Our study revealed that glucocorticoids reduced the C_min/dose levels of VRC and different SNPs of CYP450 have different effects on the C_min/dose ratio of VRC. Glucocorticoids and CYP2C19*17 mutants had a synergistic effect on reducing VRC C_min/dose. The present results suggested that when VRC is combined with glucocorticoids, we should pay more attention to the clinical efficacy of VRC, especially when CYP2C19*17 mutants exist.

Simultaneous quantitation of five triazole anti-fungal agents by paper spray-mass spectrometry

Background Invasive fungal disease is a life-threatening condition that can be challenging to treat due to pathogen resistance, drug toxicity, and therapeutic failure secondary to suboptimal drug concentrations. Frequent therapeutic drug monitoring (TDM) is required for some anti-fungal agents to overcome these issues. Unfortunately, TDM at the institutional level is difficult, and samples are often sent to a commercial reference laboratory for analysis. To address this gap, the first paper spray-mass spectrometry assay for the simultaneous quantitation of five triazoles was developed. Methods Calibration curves for fluconazole, posaconazole, itraconazole, hydroxyitraconazole, and voriconazole were created utilizing plasma-based calibrants and four stable isotopic internal standards. No sample preparation was needed. Plasma samples were spotted on a paper substrate in pre-manufactured plastic cartridges, and the dried plasma spots were analyzed directly utilizing paper spray-mass spectrometry (paper spray MS/MS). All experiments were performed on a Thermo Scientific TSQ Vantage triple quadrupole mass spectrometer. Results The calibration curves for the five anti-fungal agents showed good linearity (R2 = 0.98-1.00). The measured assay ranges (lower limit of quantification [LLOQ]-upper limit of quantitation [ULOQ]) for fluconazole, posaconazole, itraconazole, hydroxyitraconazole, and voriconazole were 0.5-50 μg/mL, 0.1-10 μg/mL, 0.1-10 μg/mL, 0.1-10 μg/mL, and 0.1-10 μg/mL, respectively. The inter- and intra-day accuracy and precision were less than 25% over the respective ranges. Conclusions We developed the first rapid paper spray-MS/MS assay for simultaneous quantitation of five triazole anti-fungal agents in plasma. The method may be a powerful tool for near-point-of-care TDM aimed at improving patient care by reducing the turnaround time and for use in clinical research.

The Current State of Antifungal Stewardship in Immunocompromised Populations

Inappropriate antifungal use is prevalent and can lead to drug-resistant fungi, expose patients to adverse drug events, and increase healthcare costs. While antimicrobial stewardship programs have traditionally focused on antibiotic use, the need for targeted antifungal stewardship (AFS) intervention has garnered interest in recent years. Despite this, data on AFS in immunocompromised patient populations is limited. This paper will review the current state of AFS in this complex population and explore opportunities for multidisciplinary collaboration.

The use of posaconazole delayed-release tablets in the successful treatment of suspected mucormycosis in a bottlenose dolphin (Tursiops truncatus) calf

Mucorales infections in cetaceans have a high mortality rate. This case report refers to a bottlenose dolphin calf with suspected mucormycosis treated with posaconazole. This antifungal agent was discontinued after 96 days of therapy, however, the infection relapsed. Posaconazole was then resumed for a total of 255 days, with no signs of disease reactivation. The retrospective analysis of posaconazole serum levels in this successful case showed concentrations varying between 5.18 and 11.63 mg/L.

Favorable Effects of Voriconazole Trough Concentrations Exceeding 1 μg/mL on Treatment Success and All-Cause Mortality: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis examined the optimal trough concentration of voriconazole for adult patients with invasive fungal infections. We used stepwise cutoffs of 0.5-2.0 μg/mL for efficacy and 3.0-6.0 μg/mL for safety. Studies were included if they reported the rates of all-cause mortality and/or treatment success, hepatotoxicity, and nephrotoxicity according to the trough concentration. Twenty-five studies involving 2554 patients were included. The probability of mortality was significantly decreased using a cutoff of ≥1.0 μg/mL (odds ratio (OR) = 0.34, 95% confidence interval (CI) = 0.15-0.80). Cutoffs of 0.5 (OR = 3.48, 95% CI = 1.45-8.34) and 1.0 μg/mL (OR = 3.35, 95% CI = 1.52-7.38) also increased the treatment success rate. Concerning safety, significantly higher risks of hepatotoxicity and neurotoxicity were demonstrated at higher concentrations for all cutoffs, and the highest ORs were recorded at 4.0 μg/mL (OR = 7.39, 95% CI = 3.81-14.36; OR = 5.76, 95% CI 3.14-10.57, respectively). Although further high-quality trials are needed, our findings suggest that the proper trough concentration for increasing clinical success while minimizing toxicity is 1.0-4.0 μg/mL for adult patients receiving voriconazole therapy.

Variability of Hydroxy-Itraconazole in Relation to Itraconazole Bloodstream Concentrations

We analyzed the relationship between itraconazole (ITZ) and hydroxy-itraconazole (OH-ITZ) levels in 1,223 human samples. Overall, there was a statistically significant correlation between ITZ and OH-ITZ levels (Pearson's r, 0.7838), and OH-ITZ levels were generally higher than ITZ levels (median OH-ITZ:ITZ ratio, 1.73; range, 0.13 to 8.96). However, marked variability was observed throughout the range of ITZ concentrations. Thus, it is difficult to predict OH-ITZ concentrations based solely on ITZ levels.

Core Recommendations for Antifungal Stewardship: A Statement of the Mycoses Study Group Education and Research Consortium

In recent years, the global public health community has increasingly recognized the importance of antimicrobial stewardship (AMS) in the fight to improve outcomes, decrease costs, and curb increases in antimicrobial resistance around the world. However, the subject of antifungal stewardship (AFS) has received less attention. While the principles of AMS guidelines likely apply to stewarding of antifungal agents, there are additional considerations unique to AFS and the complex field of fungal infections that require specific recommendations. In this article, we review the literature on AMS best practices and discuss AFS through the lens of the global core elements of AMS. We offer recommendations for best practices in AFS based on a synthesis of this evidence by an interdisciplinary expert panel of members of the Mycoses Study Group Education and Research Consortium. We also discuss research directions in this rapidly evolving field. AFS is an emerging and important component of AMS, yet requires special considerations in certain areas such as expertise, education, interventions to optimize utilization, therapeutic drug monitoring, and data analysis and reporting.

Antifungal therapy with azoles and the syndrome of acquired mineralocorticoid excess

The syndromes of mineralocorticoid excess describe a heterogeneous group of clinical manifestations leading to endocrine hypertension, typically either through direct activation of mineralocorticoid receptors or indirectly by impaired pre-receptor enzymatic regulation or through disturbed renal sodium homeostasis. The phenotypes of these disorders can be caused by inherited gene variants and somatic mutations or may be acquired upon exposures to exogenous substances. Regarding the latter, the symptoms of an acquired mineralocorticoid excess have been reported during treatment with azole antifungal drugs. The current review describes the occurrence of mineralocorticoid excess particularly during the therapy with posaconazole and itraconazole, addresses the underlying mechanisms as well as inter- and intra-individual differences, and proposes a therapeutic drug monitoring strategy for these two azole antifungals. Moreover, other therapeutically used azole antifungals and ongoing efforts to avoid adverse mineralocorticoid effects of azole compounds are shortly discussed.

Choosing Antifungals for the Midostaurin-Treated Patient: Does CYP3A4 Outweigh Recommendations? A Brief Insight from Real Life

INTRODUCTION

Patients treated with midostaurin and chemotherapy are at risk of invasive fungal disease. Prophylactic posaconazole is recommended for these patients, but posaconazole strongly inhibits the CYP3A4 isozyme that metabolizes midostaurin. Posaconazole therefore introduces a risk of patient's overexposure to midostaurin.

METHODS

Blood samples were obtained from 4 patients treated with midostaurin for newly diagnosed FLT3-mutAML. Patients had received a concomitant treatment with posaconazole, isavuconazole, or micafungin, respectively. All blood samples were drawn before daily dose administration of midostaurin.

RESULTS

Posaconazole caused a ≥8-fold increase of midostaurin plasma levels at through, which was accompanied by a decreased plasma exposure to O-demethylated or hydroxylated midostaurin metabolites. We also show that hematologists react to risk perception by replacing posaco-nazole with antifungals like micafungin or isavuconazole, which lack a strong inhibition of CYP3A4 and fail to modify midostaurin pharmacokinetics but are not formally recommended in these settings.

DISCUSSION

In real-life scenarios, concerns about CYP3A4 inhibition may outweigh compliance with recommendations. Large studies are needed to survey the risk:benefit of hematologist's decision to replace posaconazole with other antifungals.

Significant elevation of free itraconazole concentration at onset of adverse effects: A case report

Free itraconazole and hydroxyitraconazole concentrations were markedly elevated despite almost no changes in total concentrations when itraconazole was discontinued due to adverse effects. Elevated free itraconazole concentration may have a causal relationship with the development of adverse effects.

A retrospective 'real-world' cohort study of azole therapeutic drug monitoring and evolution of antifungal resistance in cystic fibrosis

BACKGROUND

Individuals with cystic fibrosis (CF) have an increased susceptibility to fungal infection/allergy, with triazoles often used as first-line therapy. Therapeutic drug monitoring (TDM) is essential due to significant pharmacokinetic variability and the recent emergence of triazole resistance worldwide.

OBJECTIVES

In this retrospective study we analysed the 'real-world' TDM of azole therapy in a large CF cohort, risk factors for subtherapeutic dosing, and the emergence of azole resistance.

METHODS

All adults with CF on azole therapy in a large single UK centre were included. Clinical demographics, TDM and microbiology were analysed over a 2 year study period (2015-17) with multivariate logistic regression used to identify risk factors for subtherapeutic dosing.

RESULTS

91 adults were treated with azole medication during the study period. A high prevalence of chronic subtherapeutic azole dosing was seen with voriconazole (60.8%) and itraconazole capsule (59.6%) use, representing significant risk factors for subtherapeutic levels. Rapid emergence of azole resistance was additionally seen over the follow-up period with a 21.4% probability of CF patients developing a resistant fungal isolate after 2 years. No significant relationship was found however between subtherapeutic azole dosing and azole resistance emergence.

CONCLUSIONS

Our study demonstrates a high prevalence of subtherapeutic azole levels in CF adults with increased risk using itraconazole capsules and voriconazole therapy. We show rapid emergence of azole resistance highlighting the need for effective antifungal stewardship. Further large longitudinal studies are needed to understand the effects of antifungal resistance on outcome in CF and the implications of subtherapeutic dosing on resistance evolution.

Using Child-Pugh Class to Optimize Voriconazole Dosage Regimens and Improve Safety in Patients with Liver Cirrhosis: Insights from a Population Pharmacokinetic Model-based Analysis

BACKGROUND

Cirrhotic patients are at a high risk of fungal infections. Voriconazole is widely used as prophylaxis and in the treatment of invasive fungal disease. However, the safety, pharmacokinetics, and optimal regimens of voriconazole are currently not well defined in cirrhotic patients.

DESIGN

Retrospective pharmacokinetics study.

SETTING

Two large, academic, tertiary-care medical center.

PATIENTS

Two hundred nineteen plasma trough concentrations (C_min ) from 120 cirrhotic patients and 83 plasma concentrations from 11 non-cirrhotic patients were included.

METHODS

Data pertaining to voriconazole were collected retrospectively. A population pharmacokinetics analysis was performed and model-based simulation was used to optimize voriconazole dosage regimens.

RESULTS

Voriconazole-related adverse events (AEs) developed in 29 cirrhotic patients, and the threshold C_min for AE was 5.12 mg/L. A two-compartment model with first-order elimination adequately described the data. The Child-Pugh class and body weight were the significant covariates in the final model. Voriconazole clearance in non-cirrhotic, Child-Pugh class A and B cirrhotic (CP-A/B) and Child-Pugh class C cirrhotic (CP-C) patients was 7.59, 1.86, and 0.93 L/hour, respectively. The central distribution volume and peripheral distribution volume was 100.8 and 55.2 L, respectively. The oral bioavailability was 91.6%. Model-based simulations showed that a loading dose regimen of 200 mg/12 hours intravenously or orally led to 65.0-75.7% of voriconazole C_min in therapeutic range on day 1, and the appropriate maintenance dosage regimens were 75 mg/12 hours and 150 mg/24 hours intravenously or orally for CP-A/B patients, and 50 mg/12 hours and 100 mg/24 hours intravenously or orally for CP-C patients. The predicted probability of achieving the therapeutic target concentration for optimized regimens at steady-state was 66.8-72.3% for CP-A/B patients and 70.3-74.0% for CP-C patients.

CONCLUSIONS

These results recommended that the halved loading dose regimens should be used, and voriconazole maintenance doses in cirrhotic patients should be reduced to one-fourth for CP-C patients and to one-third for CP-A/B patients compared to that for patients with normal liver function.

Optimization of Fluconazole Dosing for the Prevention and Treatment of Invasive Candidiasis Based on the Pharmacokinetics of Fluconazole in Critically Ill Patients

The efficacy of fluconazole is related to the area under the plasma concentration-time curve (AUC) over the MIC of the microorganism. Physiological changes in critically ill patients may affect the exposure of fluconazole, and therefore dosing adjustments might be needed. The aim of this study was to evaluate variability in fluconazole drug concentration in intensive care unit (ICU) patients and to develop a pharmacokinetic model to support personalized fluconazole dosing. A prospective observational pharmacokinetic study was performed in critically ill patients receiving fluconazole either as prophylaxis or as treatment. The association between fluconazole exposure and patient variables was studied. Pharmacokinetic modeling was performed with a nonparametric adaptive grid (NPAG) algorithm using R package Pmetrics. Data from 33 patients were available for pharmacokinetic analysis. Patients on dialysis and solid organ transplant patients had a significantly lower exposure to fluconazole. The population was best described with a one-compartment model, where the mean volume of distribution was 51.52 liters (standard deviation [SD], 19.81) and the mean clearance was 0.767 liters/h (SD, 0.46). Creatinine clearance was tested as a potential covariate in the model, but was not included in the final population model. A significant positive correlation was found between the fluconazole exposure (AUC) and the trough concentration (C _min). Substantial variability in fluconazole plasma concentrations in critically ill adults was observed, where the majority of patients were underexposed. Fluconazole C _min therapeutic drug monitoring (TDM)-guided dosing can be used to optimize therapy in critically ill patients. (This study has been registered at ClinicalTrials.gov under identifier NCT02491151.).

Model-Optimized Fluconazole Dose Selection for Critically Ill Patients Improves Early Pharmacodynamic Target Attainment without the Need for Therapeutic Drug Monitoring

Fluconazole has been associated with higher mortality compared with the echinocandins in patients treated for invasive candida infections. Underexposure from current fluconazole dosing regimens may contribute to these worse outcomes, so alternative dosing strategies require study. The objective of this study was to evaluate fluconazole drug exposure in critically ill patients comparing a novel model-optimized dose selection method with established approaches over a standard 14-day (336-h) treatment course. Target attainment was evaluated in a representative population of 1,000 critically ill adult patients for (i) guideline dosing (800-mg loading and 400-mg maintenance dosing adjusted to renal function), (ii) guideline dosing followed by therapeutic drug monitoring (TDM)-guided dose adjustment, and (iii) model-optimized dose selection based on patient factors (without TDM). Assuming a MIC of 2 mg/liter, free fluconazole 24-h area under the curve (fAUC24) targets of ≥200 mg · h/liter and <800 mg · h/liter were used for assessment of target attainment. Guideline dosing resulted in underexposure in 21% of patients at 48 h and in 23% of patients at 336 h. The TDM-guided strategy did not influence 0- to 48-h target attainment due to inherent procedural delays but resulted in 37% of patients being underexposed at 336 h. Model-optimized dosing resulted in ≥98% of patients meeting efficacy targets throughout the treatment course, while resulting in less overexposure compared with guideline dosing (7% versus 14%) at 336 h. Model-optimized dose selection enables fluconazole dose individualization in critical illness from the outset of therapy and should enable reevaluation of the comparative effectiveness of this drug in patients with severe fungal infections.

Validation of a novel causality assessment scale for adverse events in non-small cell lung carcinoma patients treated with platinum and pemetrexed doublet chemotherapy

Aim:

Accurate causality assessment (CA) of adverse events (AEs) is important in clinical research and routine clinical practice. The Naranjo scale (NS) used for CA lacks specificity, leading to a high rate of false positive causal associations. NS is a simple scale for CA; however, its limitations have reduced its popularity in favour of other scales. We therefore attempted to improvise the algorithm by addressing specific lacunae in NS.

Methods:

We attempted to modify the existing NS by (a) changing the weightage given to certain responses, (b) achieving higher resolution to certain responses for delineating drug related and unrelated AEs and (c) modifying the slabs for classification of association as ‘likely’ and ‘unlikely’. The new scale, named as the Sharma-Nookala-Gota (SNG) algorithm, was evaluated in a training set of 19 AEs in a tertiary care cancer hospital in western India, and further validated in a set of 104 AEs. Consensus of four physician opinion was taken as gold standard for comparison.

Results:

Of the 19 AEs in the training set, 6 were described by the treating physician as ‘not related’ and 13 as related to the drug. The SNG algorithm had 100% concordance with physician opinion, whereas the NS had only 73.7% concordance. NS showed a tendency to misclassify AEs as ‘related’ when they were indeed ‘not related’. In the validation set of 104 AEs, NS and SNG algorithms misclassified 30 and 2 AEs, respectively, leading to a concordance of 70.2% and 98.1%, respectively, with physician opinion.

Conclusion:

Decisive modifications of the NS resulted in the SNG scale, with superior specificity while retaining sensitivity against the gold standard.

Plain Language Summary

SNG algorithm – A novel tool for causality assessment of adverse drug reactions

Adverse events (AEs) can cause increased morbidity, hospitalisation, and even death. Hence it is essential to recognise AEs and to establish their correct causal relationship to a drug. Many causality assessment methods, scales and algorithms are available to assess the relationship between an AE and a drug. The Naranjo algorithm is most commonly employed in spite of its many drawbacks as it is simple to use. Concerns have been raised regarding the performance of the scale, and researchers have tried to answer them, but none of them could address all issues satisfactorily. We too experienced many problems while using it in our routine clinical practice and in clinical trials. For instance, the Naranjo scale is non-specific and shows a bias toward implicating the drug as the causal factor for AEs. This improper assessment has often led to drug discontinuation, thereby compromising the efficacy of treatment. Hence, we modified the existing Naranjo scale to a new one (the Sharma-Nookala-Gota – SNG algorithm) to address these shortcomings. We piloted the SNG causality assessment algorithm in patients suffering from AEs due to various drugs. The SNG algorithm was found to have good concordance with the physicians’ assessment of causality. As a next step, we validated the SNG algorithm in patients receiving a standard drug combination of pemetrexed and carboplatin for lung cancer combination. Out of the 104 AEs observed in 65 patients, the SNG causality assessment algorithm showed good concordance (except in two cases) with the physicians’ decision of causality assessment, while the Naranjo algorithm was not so successful. Hence, the SNG algorithm can be a better guide for causality assessment of AEs.

Simultaneous analysis of drugs administered to lung-transplanted patients using liquid chromatography-tandem mass spectrometry for therapeutic drug monitoring

Several drugs are administered to lung-transplanted patients, which are monitored using therapeutic drug monitoring (TDM). Therefore, we developed and validated a liquid chromatography-tandem mass spectrometry method to simultaneously analyze immunosuppressive drugs such as mycophenolic acid, antifungal drugs such as voriconazole and itraconazole, and its metabolite hydroxyitraconazole. Chromatographic separation was achieved using a C18 column and gradient flow of mobile phase comprising 20 mM aqueous ammonium formate and 20 mM ammonium formate-methanol solution. A simple protein precipitation treatment was performed using acetonitrile/methanol and mycophenolic acid-² H₃ , voriconazole-² H₃ , itraconazole-² H₄ , and hydroxyitraconazole-² H₄ as internal standards. The linearity ranges of mycophenolic acid, voriconazole, itraconazole, and hydroxyitraconazole were 100-20,000, 50-10,000, 5-1000, and 5-1000 ng/mL, respectively. The retention time of each target was less than 2 min. The relative errors in intra- and inter-day were within ±7.6%, the coefficient of variation was 8.9% or less for quality control low, medium, and high, and it was 15.8% or less for lower limit of quantitation. Moreover, the patient samples were successfully quantified, and they were within the linear range of measurements. Therefore, our new method may be useful for TDM in lung-transplanted patients.

Roles for Structural Biology in the Discovery of Drugs and Agrochemicals Targeting Sterol 14α-Demethylases

Antifungal drugs and antifungal agrochemicals have significant limitations. These include several unintended consequences of their use including the growing importance of intrinsic and acquired resistance. These problems underpin an increasingly urgent need to improve the existing classes of antifungals and to discover novel antifungals. Structural insights into drug targets and their complexes with both substrates and inhibitory ligands increase opportunity for the discovery of more effective antifungals. Implementation of this promise, which requires multiple skill sets, is beginning to yield candidates from discovery programs that could more quickly find their place in the clinic. This review will describe how structural biology is providing information for the improvement and discovery of inhibitors targeting the essential fungal enzyme sterol 14α-demethylase.

Correlation between enzyme multiplied immunoassay technique and high-performance liquid chromatography in the quantification of voriconazole in a paediatric population

The enzyme multiplied immunoassay technique (EMIT) is a new method for determining the plasma concentration of voriconazole (VRZ). This study aimed to investigate the correlation between EMIT and high-performance liquid chromatography/ultraviolet rays (HPLC/UV) in determining the plasma VRZ trough concentration in children, in China. A total of 419 blood samples were collected, and plasma VRZ concentrations were detected by the EMIT and HPLC methods. The results of 304 samples were analysed after excluding samples that were undetectable or beyond the quantification limit. A test result value of 0 was defined as undetectable, while concentrations outside the detection range (0.2 - 20.0 μg/ml for HPLC and 0.5 - 16.0 µg/ml for EMIT) were defined as beyond the quantification limit. Results from both methods were compared using the Passing Bablok regression, Bland-Altman plot analysis, and paired Wilcoxon test. The plasma VRZ concentrations determined by EMIT and HPLC showed a strong linear correlation through the linear regression equation Y_EMIT = 1.310 × HPLC +0.149 (R² = 0.9082). The Bland-Altman plot analysis showed poor level consistency as measured by the two methods. The paired Wilcoxon-test showed a significant difference between the two methods (p < .0001). Compared to EMIT, HPLC accurately detected plasma VRZ concentration, making it suitable for VRZ therapeutic drug monitoring. The numerical values of the EMIT-measured levels were higher than those of HPLC, which may be related to VRZ metabolites interference and co-administrated drugs.

Rapid and Simple Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC) Method for Simultaneous Quantifications of Triazole Antifungals in Human Serum

PURPOSE

To develop and validate a one-step, rapid and simple reversed-phase high-performance liquid chromatography (HPLC)-based protocol for the simultaneous measurement of voriconazole (VCZ), posaconazole (POSA), itraconazole (ITC) in serum/plasma.

METHODS

Calibration standards (CS) and quality control samples were prepared in drug-free serum by spiking with the triazoles at different concentrations. HPLC was performed with C₁₈ column, isocratic mobile phase after extraction with cold acetonitrile. The standardized method was tested in 2693 patients' serum/plasma samples.

RESULTS

Linearity of CS for ITC, VCZ and POSA was proportional to the nominal concentration (correlation coefficient > 0.999). Limit of detection (mg/L) for ITC, VCZ and POSA was 0.25, 0.25 and 0.125, respectively. The lower limit of quantification (mg/L) for ITC, VCZ and POSA was 0.5, 0.5 and 0.25, respectively. Precision and accuracy were in acceptable range with 100% average percentage recovery. No interferences from endogenous substances and other antimicrobial compounds were noted. In clinical samples, the therapeutic range achieved for VCZ was 39.9%. Whereas, 61.1% and 44% of samples with ITC and POSA, respectively, were in the sub-therapeutic range.

CONCLUSION

We developed a rapid and simple HPLC method to quantify common triazoles in a single chromatographic run allowing simultaneous measurement of different antifungals in a small volume of serum/plasma. Thus, therapeutic drug monitoring requests can be processed in one run without changing the protocol parameters, column or column conditioning thereby improving turnaround time.

Optimal trough concentration of voriconazole with therapeutic drug monitoring in children: A systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis was designed to determine the optimal trough concentration of voriconazole for children with invasive fungal infections (IFIs).

METHODS

We searched electronic databases (PubMed, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov and Japana Centra Revuo Medicina) for clinical studies describing the voriconazole trough concentration. We used stepwise cut-off values of 1.0-2.0 mg/L for efficacy and 3.0-6.0 mg/L for safety. The efficacy outcomes were treatment success and all-cause mortality, and the safety outcomes were hepatotoxicity, neurotoxicity and all-cause adverse events.

RESULTS

Nine studies involving 211 patients were included in the analysis. The probability of treatment success against IFIs was significantly increased at cut-off values of ≥1.0 mg/L (odds ratio [OR] = 2.65, 95% confidence interval [CI] = 1.20-5.87). Our analysis did not find any relationship between the trough concentration and survival. Concerning safety, the occurrence of any outcomes did not significantly differ according to the voriconazole trough concentrations at any cut-off value. However, in a subgroup analysis of Asian study locations, a significantly higher risk of hepatotoxicity was demonstrated at voriconazole trough cut-off values ≥ 3.0 mg/L (OR = 8.40, 95% CI = 1.36-51.92). Although a significant correlation between the voriconazole concentration and hepatotoxicity was evident in regression curve analysis, (y = 0.1198e^0.2298x), no correlation was demonstrated for neurotoxicity (y = 0.3913e^-0.008x).

CONCLUSION

Our findings suggest that the optimal trough concentration for increasing clinical success and minimizing hepatotoxicity during voriconazole therapy in children with IFIs, particularly for Asian populations, is 1.0-3.0 mg/L.

Decreasing voriconazole requirement in a patient after extracorporeal membrane oxygenation discontinuation: A case report

Patients receiving extracorporeal membrane oxygenation (ECMO) may display large decreases in drug concentrations due to increases in volume of distribution and drug binding to ECMO circuits, tubing, oxygenator, and coating materials. We report a case of a critically ill male with a 10-month status post-deceased donor renal transplant and being treated with voriconazole for suspected aspergillosis. Initially, multiple dose increases, up to 11.3 mg/kg/dose, were required while on ECMO therapy to obtain goal voriconazole trough concentrations between 2 and 5.5 mcg/mL. The patient's voriconazole dose requirement subsequently decreased to 7.3 mg/kg/dose after ECMO discontinuation, which represented a 45% reduction in voriconazole dose requirement. Based upon this experience, voriconazole appears to bind to artificial surfaces on ECMO devices. In addition to close monitoring of trough levels, it may be appropriate to empirically reduce the voriconazole dose in patients after ECMO discontinuation.

Pharmacokinetics of flucytosine in a critically ill patient on continuous venovenous hemodiafiltration

PURPOSE

To describe the pharmacokinetics of flucytosine in a critically ill patient undergoing continuous venovenous hemodiafiltration (CVVHDF) treated for cryptococcal meningitis.

SUMMARY

A 20-year-old female weighing 93.4 kg with a body mass index of 34.3 kg/m2 with a past medical history of systemic lupus erythematous with diffuse proliferative lupus nephritis (class IV) was admitted to the hospital after several months of worsening dyspnea, fatigue, myalgia, vomiting, and diarrhea. The patient developed worsening renal function and volume overload requiring CVVHDF on hospital day 7. She was diagnosed with cryptococcal meningitis on hospital day 8, and flucytosine 2,500 mg enterally every 12 hours and liposomal amphotericin B 500 mg intravenously every 24 hours were initiated. Flucytosine serum concentrations were collected on day 4 of therapy, and pharmacokinetics were performed on 2 sequential levels. Pharmacokinetic calculations displayed an elimination rate constant of 0.0338 h-1, a volume of distribution between 0.42 and 0.43 L/kg, a half-life of 20.5 hours, and a total drug clearance between 1.32 and 1.36 L/h while on CVVHDF. The nonsequential levels displayed good correlation, and no further monitoring or dosage adjustment was required. The patient completed therapy, with clinical resolution of her infection, and no toxicities due to flucytosine were noted.

CONCLUSION

Flucytosine dosed at 25 mg/kg of actual body weight every 12 hours during CVVHDF conferred therapeutic levels with no appreciable toxicities. Because of its narrow therapeutic index and risk of toxicity, additional pharmacokinetic studies are needed to determine optimal drug dosing of this medication in patients requiring renal replacement therapy.

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

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

Factors Associated With Voriconazole Concentration in Pediatric Patients

BACKGROUND

Serum concentrations of voriconazole are difficult to predict, especially in pediatric patients, because of its complex pharmacokinetic characteristics. This study aimed to identify the factors associated with the concentration of voriconazole in pediatric patients.

METHODS

This cohort study was based on retrospective data collection and involved the administration of voriconazole to pediatric patients younger than 18 years, between January 2010 and August 2017. Electronic medical records of the patients were reviewed to collect demographic characteristics, voriconazole treatment regimen, and factors that could potentially influence voriconazole trough concentrations. A voriconazole trough serum concentration of less than 1.0 mcg/mL or greater than 5.5 mcg/mL was defined as outside the therapeutic range and was set as the outcome of this study.

RESULTS

Among the 114 patients enrolled, 61 patients were included in the analysis. Oral administration of a maintenance dose of voriconazole and C-reactive protein (CRP) level were significantly and independently associated with a low initial trough concentration of voriconazole (<1.0 mcg/mL). Alanine aminotransferase levels were a significant factor associated with a high initial trough concentration of voriconazole (>5.5 mcg/mL) after adjusting for sex, age, weight, and serum creatinine (odds ratio 5.42; 95% confidence interval 1.34-21.97).

CONCLUSIONS

Considering the variability of voriconazole concentrations in pediatric patients, monitoring certain parameters and considering the route of administration could help determine the therapeutic range of voriconazole and subsequently avoid unwanted effects.

Remission of hepatotoxicity in chronic pulmonary aspergillosis patients after lowering trough concentration of voriconazole

BACKGROUND

Chronic pulmonary aspergillosis (CPA) is a rare syndrome that is often accompanied by gradual lung tissue destruction. Voriconazole is usually employed as the first-line agent for CPA treatment. However, some patients can develop hepatotoxicity and often were forced to stop voriconazole treatment.

AIM

To record the improving trend of liver function and the therapeutic effects in patients after lowering the trough concentration of voriconazole.

METHODS

This study retrospectively analyzed 12 adult CPA patients who developed hepatotoxicity during the voriconazole treatment. In these patients, the oral dose was reduced to 3/4 or 1/2 of the standard dose (4 mg/kg, twice daily), and the lower limit of voriconazole trough concentration was maintained more than 0.5 µg/mL. The trend of remission of liver toxicity after drug reduction in 12 patients was recorded. During the same period, 25 patients who received standard doses served as the control group. Data from the two groups were collected and analyzed for different parameters such as demographic characteristics, underlying pulmonary disorders, laboratory tests, and therapeutic effect. The differences between the two groups were statistically compared.

RESULTS

Hepatotoxicity occurred in 12 patients within 28-65 d after oral voriconazole treatment. Hepatotoxicity was mainly manifested by the significantly increased level of gamma-glutamyltransferase and a slight increase of alanine aminotransferase and aspartate aminotransferase. The oral dose of voriconazole was reduced to approximately 3 mg/kg in seven patients and approximately 2 mg/kg in five patients. The average trough concentrations for the 12 patients before and after voriconazole oral dose reduction were 3.17 ± 1.47 µg/mL (1.5-6.0 µg/mL) and 1.70 ± 0.78 µg/mL (0.6-3.3 µg/mL), respectively (P = 0.02). After lowering the trough concentrations, the hepatotoxicity was alleviated in all the patients. However, gamma-glutamyltransferase levels declined slowly. After 4 mo of treatment, 7 of the 12 patients were successfully treated in the low trough concentrations group (41.7%). Similarly, 8 of the 25 patients in the standard treatment dose group (32.0%) were effectively treated. There was no statistical difference between the groups (P = 0.72).

CONCLUSION

Reducing the lower limit of the voriconazole trough concentration to 0.5 µg/mL can alleviate the hepatotoxicity and maintained certain clinical efficacy in CPA patients; however, patients should be closely monitored.

Pharmacist review of high-risk haematology outpatients to improve appropriateness of antifungal prophylaxis

Background Patients with haematological malignancies are at high risk of invasive fungal infections. However, there is a lack of information about the utilisation of the recommended Australian antifungal prophylaxis guidelines in haematology outpatients. Objective To assess the impact of a weekly pharmacist review of high-risk adult haematology outpatients on the utilisation of appropriate antifungal prophylaxis. Setting Outpatient cancer centre, tertiary referral hospital in Sydney, Australia. Method A 3-month pre-and post-interventional study was conducted. A retrospective audit was conducted to obtain baseline utilisation of antifungal guidelines in adult haematology outpatients with acute myeloid leukemia, acute lymphoblastic leukemia and myelodysplastic syndrome receiving chemotherapy. This was followed by a weekly pharmacist review over a 3-month period of all eligible outpatients assessing the appropriateness of antifungal agent, dose, use of therapeutic drug monitoring and presence of drug-interactions/contraindications. Recommendations to physicians were conveyed weekly and outcomes recorded. Main outcome measure Appropriate utilisation of antifungal prophylaxis guidelines in outpatient haematology patients before and after implementation of a 3-month weekly pharmacist review service. Results Forty patients were included in the retrospective group, equating to 348 reviews, while 42 patients equating to 269 reviews were included in the prospective group. Appropriate utilisation of antifungal prophylaxis guidelines increased from 31 to 54% post implementation of a pharmacist review (Odds Ratio = 2.44, 95% Confidence Interval: 1.07-5.58, p = 0.0344). The most common reason for nonadherence to guidelines in both groups was lack of therapeutic drug monitoring and failure to prescribe antifungal prophylaxis where indicated. The percentage of appropriate use of antifungal prophylaxis in patients with acute myeloid leukemia increased from 13 to 46% (p value < 0.01) after pharmacist intervention. The pharmacist made 153 recommendations from 269 reviews, with a percentage uptake of 40%. Moderate to severe drug interactions were identified in 19 reviews from 10 patients. One major azole antifungal-chemotherapy interaction was avoided. Conclusions Appropriate utilisation of antifungal prophylaxis guidelines can be improved through a regular pharmacist review. Future studies should identify whether improving adherence to antifungal guidelines leads to improved patient outcomes.

Randomised multicentre clinical trial to evaluate voriconazole pre-emptive genotyping strategy in patients with risk of aspergillosis: vorigenipharm study protocol

INTRODUCTION

Invasive aspergillosis is the most important cause of morbidity and mortality in patients with haematological diseases. At present, voriconazole is the first-line treatment for invasive fungal disease. The pharmacokinetic interindividual variability of voriconazole depends on genetic factors. CYP450 is involved in 70%-75% of total metabolism of voriconazole, mainly CYP3A4 and CYP2C19, with the remaining 25%-30% of metabolism conducted by monooxygenase flavins. CYP2C19 single nucleotide polymorphisms could explain 50%-55% of variability in voriconazole metabolism.

MATERIALS AND METHODS

The main objective is to compare efficiency of pre-emptive voriconazole genotyping with routine practice. The primary outcome is serum voriconazole on the fifth day within the therapeutic range. The secondary outcome is the combined variables of therapeutic failure and adverse events within 90 days of first administration, associated with voriconazole. A total of 146 patients at risk of invasive aspergillosis who will potentially receive voriconazole will be recruited, and CYP2C19 will be genotyped. If the patient ultimately receives voriconazole, they will be randomised (1:1 experimental/control). In the experimental arm, patients will receive a dose according to a pharmacogenetic algorithm, including CYP2C19 genotype and clinical and demographic information. In the control arm, patients will receive a dose according to clinical practice guidelines. In addition, a Spanish National Healthcare System (NHS) point-of-view cost-effectiveness evaluation will be performed. Direct cost calculations for each arm will be performed.

CONCLUSION

This trial will provide information about the viability and cost-effectiveness of the implementation of a pre-emptive voriconazole genotyping strategy in the Spanish NHS.

ETHICS AND DISSEMINATION

A Spanish version of this protocol has been evaluated and approved by the La Paz University Hospital Ethics Committee and the Spanish Agency of Medicines and Medical Devices. Trial results will be submitted for publication in an open peer-reviewed medical speciality-specific publication.

TRIAL REGISTRATION NUMBER

Eudra-CT: 2019-000376-41 and NCT04238884; Pre-results.

Resistance to echinocandin antifungal agents in the United Kingdom in clinical isolates of Candida glabrata: Fifteen years of interpretation and assessment

Candidemia is widely reported as the fourth most common form of bloodstream infection worldwide. Reports of breakthrough cases of candidemia are increasing, especially in the context of a move away from azole antifungals as prophylactic or first line treatment toward the use of echinocandin agents. The global evaluation of echinocandin antifungal susceptibility since 2003 has included switches in testing methodologies and the move to a sentinel echinocandin approach for classification reporting. This study compiles previously unpublished data from echinocandin susceptibility testing of UK clinical isolates of C. glabrata received at the Public Health England Mycology Reference Laboratory from 2003 to 2016 and reevaluates the prevalence of resistance in light of currently accepted testing protocols. From 2015 onward, FKS gene mutation detection using a novel Pyrosequencing® assay was assessed as a predictor of echinocandin resistance alongside conventional susceptibility testing. Overall, our data show that echinocandin resistance in UK isolates of C. glabrata is a rare phenomenon and prevalence has not appreciably increased in the last 14 years. The pyrosequencing assay was able to successfully detect hot spot mutations in FKS1 and FKS2, although not all isolates that exhibited phenotypic resistance demonstrated detectable hot spot mutations. We propose that a rapid genomic based detection method for FKS mutations, as part of a multifactorial approach to susceptibility testing, could help provide accurate and timely management decisions especially in regions where echinocandin resistance has been reported to be emerging in this important pathogen.

Impact of Albumin and Omeprazole on Steady-State Population Pharmacokinetics of Voriconazole and Development of a Voriconazole Dosing Optimization Model in Thai Patients with Hematologic Diseases

This study aimed to identify factors that significantly influence the pharmacokinetics of voriconazole in Thai adults with hematologic diseases, and to determine optimal voriconazole dosing regimens. Blood samples were collected at steady state in 65 patients (237 concentrations) who were taking voriconazole to prevent or treat invasive aspergillosis. The data were analyzed using a nonlinear mixed-effects modeling approach. Monte Carlo simulation was applied to optimize dosage regimens. Data were fitted with the one-compartment model with first-order absorption and elimination. The apparent oral clearance (CL/F) was 3.43 L/h, the apparent volume of distribution (V/F) was 47.6 L, and the absorption rate constant (Ka) was fixed at 1.1 h⁻¹. Albumin and omeprazole ≥ 40 mg/day were found to significantly influence CL/F. The simulation produced the following recommended maintenance doses of voriconazole: 50, 100, and 200 mg every 12 h for albumin levels of 1.5–3, 3.01–4, and 4.01–4.5 g/dL, respectively, in patients who receive omeprazole ≤ 20 mg/day. Patients who receive omeprazole ≥ 40 mg/day and who have serum albumin level 1.5–3 and 3.01–4.5 g/dL should receive voriconazole 50 and 100 mg, every 12 h, respectively. Albumin level and omeprazole dosage should be carefully considered when determining the appropriate dosage of voriconazole in Thai patients.

Initial posaconazole dosing to achieve therapeutic serum posaconazole concentrations among children, adolescents, and young adults receiving delayed-release tablet and intravenous posaconazole

Posaconazole is a broad-spectrum antifungal used for prophylaxis and treatment of invasive fungal diseases. There are limited data on the optimal dosing, safety, and efficacy of the DRT and IV formulations in immunocompromised pediatric and adolescent patients. We describe our experience including dosing, plasma trough concentrations, safety, and tolerability. Plasma concentrations ≥.7 µg/mL were considered therapeutic for prophylaxis and ≥1.0 µg/mL for treatment. Fifty-four patients (median age of 16 years) received DRT or IV formulations of posaconazole. Thirty-one (57%) patients received posaconazole for treatment and 23 (43%) for prophylaxis. Overall, 36 (67%) patients achieved targeted initial plasma trough concentrations (median 1.3 µg/mL) (Figure 1). The median daily dose among patients <13 years of age who achieved the targeted initial concentrations was 7.3 mg/kg/day for the DRT formulation and 9.8 mg/kg/day for the IV formulation. The median daily dose among patients ≥13 years of age who achieved the targeted initial concentrations was 4.9 mg/kg/day for the DRT formulation and 5.6 mg/kg/day for the IV formulation. Thirty-six patients (67%) developed transaminitis, mostly grade 1. Our observations show that DRT and IV formulations are safe and effective in immunocompromised children, adolescents, and young adults. Higher dosing per body weight of DRT and IV posaconazole may be required in patients <13 years of age compared with patients 13 years of age and older to achieve therapeutic plasma concentrations. [Figure: see text].

Evaluation of targeted versus universal prophylaxis for the prevention of invasive fungal infections following lung transplantation

BACKGROUND

Antifungal prophylaxis to prevent invasive fungal infections (IFI) is widely used following lung transplantation, but the optimal strategy remains unclear. We compared universal with targeted antifungal prophylaxis for effectiveness in preventing IFI.

METHODS

Adult patients who underwent lung transplantation at the University of Michigan from /1 July 2014-31 December 2017 were studied for 18 months post-transplant. Universal prophylaxis consisted of itraconazole with or without inhaled liposomal amphotericin B. Using specific criteria, targeted prophylaxis was given with voriconazole for patients at risk for invasive pulmonary aspergillosis (IPA) and with fluconazole or micafungin for patients at risk for invasive candidiasis. Risk factors, occurrence of proven/probable IFI, and mortality were analyzed for the two prophylaxis cohorts.

RESULTS

Of 105 lung transplant recipients, 84 (80%) received a double lung transplant, and 38 (36%) of patients underwent transplant for pulmonary fibrosis. Fifty-nine (56%) patients received universal antifungal prophylaxis, and 46 (44%), targeted antifungal prophylaxis. Among 20 proven/probable IFI, there were 14 IPA, 4 invasive candidiasis, 1 cryptococcosis, and 1 deep sternal mold infection. Six (10%) IFI occurred in the universal prophylaxis cohort and 14 (30%) in the targeted prophylaxis cohort. Five of 6 (83%) IFI in the universal prophylaxis cohort, compared with 9/14 (64%) in the targeted prophylaxis cohort, were IPA Candida infections occurred only in the targeted prophylaxis cohort. The development of IFI was more likely in the targeted prophylaxis cohort than the universal prophylaxis cohort, HR = 4.32 (1.51-12.38), P = .0064.

CONCLUSIONS

Universal antifungal prophylaxis appears to be more effective than targeted antifungal prophylaxis for prevention of IFI after lung transplant.