Voriconazole therapeutic drug monitoring and hepatotoxicity in critically ill patients: A nationwide multi-centre retrospective study

Case report: dose-dependent interaction between dexamethasone and voriconazole in severely ill patients with non-Hodgkin's lymphoma being treated for invasive pulmonary aspergillosis

Background

Voriconazole is primarily metabolized by CYP2C19 and CYP3A4. Drug interactions that affect this pathway can alter its plasma exposures, resulting in untargeted voriconazole concentrations.

Case summary

In this case report, we describe the case of a 64-year-old man who was treated for non-Hodgkin's lymphoma with continuous glucocorticoids co-administrated with voriconazole against invasive pulmonary aspergillosis. A decrease in trough concentration (Cmin) of voriconazole was observed and related with co-administration of dexamethasone in the patient carrying the CYP2C19 *1*2 genotype: voriconazole Cmin/dose ratios of 0.018 (0.1 mg L-1/5.7 mg kg-1 day-1), 0.18 (1 mg L-1/5.7 mg kg-1 day-1), and 0.23 (2 mg L-1/8.6 mg kg-1 day-1) at dexamethasone doses of 20, 12.5, and 2.5 mg, respectively. Sub-therapeutic voriconazole Cmin was associated with high- and moderate-dose dexamethasone (20 and 12.5 mg), leading to failure of antifungal treatment.

Conclusion

The extent of voriconazole-dexamethasone interaction was determined by the dose of dexamethasone and associated with the CYP2C19 *1*2 genotype. Therapeutic drug monitoring of voriconazole is necessary to avoid clinically relevant interactions for optimal antifungal therapy.

Pharmacogenetic implementation for CYP2C19 and pharmacokinetics of voriconazole in children with malignancy or inborn errors of immunity

BACKGROUND

Voriconazole pharmacokinetics (PK) are known to be affected by genetic polymorphisms of drug-metabolizing enzymes such as CYP2C19; however, such information is limited for the pediatric population. The primary aim of this study is to establish a voriconazole PK model incorporating CYP2C19 phenotypes in Japanese children with malignancy or inborn errors of immunity.

METHODS

CYP2C19 genotypes were assessed by whole-genome genotyping and defined as follows: *17/*17: ultrarapid metabolizer (URM), *1/*17: rapid metabolizer (RM), *1/*1:normal metabolizer (NM), *1/*2, *1/*3, *2/*17:intermediate metabolizer (IM), and *2/*2, *2/*3, *3/*3: poor metabolizer (PM). Population PK analysis was performed. The voriconazole serum concentration profile was described by a two-compartment model with first-order absorption, mixed linear and nonlinear (Michaelis-Menten) elimination.

RESULTS

Voriconazole concentration data were available from 60 patients with a median age of 5.3 years. The phenotypes predicted from CYP2C19 genotypes were RM in 1 (2 %), NM in 21 (35 %) patients, IM in 27 (45 %) patients, and PM in 11 (18 %) patients. Underlying diseases included 38 (63%) patients with hematological malignancy and 18 (30 %) patients with inborn errors of immunity. Among the CYP2C19 phenotypes, PM was predicted to show complete inhibition (the degree of Vmax inhibition [Vmax, inh] = 100 %; Vmax = 0). The estimated parameters of Vmax,inh were +0.8 higher in patients with gamma-glutamyl transpeptidase (γ-GTP) Grade 2 or higher and +2.7 higher when C-reactive protein (CRP) levels were 2.0 mg/dL or higher.

CONCLUSION

CYP2C19 genetic polymorphisms, γ-GTP, and CRP affect Vmax,inh of voriconazole in children with malignancy or inborn errors of immunity.

Population Pharmacokinetics of Voriconazole and Dose Optimization in Elderly Chinese Patients

Voriconazole is commonly recommended as a first-line therapy for invasive aspergillosis infections. Elderly patients are susceptible to infectious diseases owing to their decreased physical function and immune system. Our study aims to establish a population pharmacokinetics model for elderly patients receiving intravenous voriconazole, and to optimize dosing protocols through a simulated approach. An accurate fit to the concentration-time profile of voriconazole was achieved by employing a 1-compartment model featuring first-order elimination. The typical clearance rate of voriconazole was found to be 3.22 L/h, with a typical volume of distribution of 194 L. The covariate analysis revealed that albumin (ALB), gamma-glutamyl transpeptidase, and direct bilirubin had significant impacts on voriconazole clearance. Additionally, body weight was found to be associated with the volume of distribution. Individualized dosing regimens were recommended for different ALB levels based on population pharmacokinetics model prediction. The proposed dosing regimens could provide a rationale for dosage individualization, improve the clinical outcomes, and minimize drug-related toxicities.

Nomogram for the prediction of tigecycline-induced hypofibrinogenaemia in a Chinese population

BACKGROUND

Tigecycline has been widely used for multi-drug-resistant bacterial infections in China. Although many studies have reported the risk factors for tigecycline-induced hypofibrinogenaemia, it remains unknown whether valproic acid or voriconazole in combination with tigecycline is associated with the decrease in fibrinogen, as both drugs could lead to coagulation disorders. The aim of this study was to develop a nomogram for the prediction of tigecycline-induced hypofibrinogenaemia.

METHODS

This was a multi-centre retrospective case-control study. The primary outcome was the accurate prediction of tigecycline-induced hypofibrinogenaemia. Nomograms were developed from logistic regression models with least absolute shrinkage and selection operator regression for variable selection. Model performance was assessed via calibration plots, and models were validated internally using bootstrapping on a validation cohort.

RESULTS

In total, 2362 patients were screened, of which 611 were eligible for inclusion in this study. These 611 patients were divided into the training cohort (n=488) and the validation cohort (n=123). Predictors included in the nomogram for the total population were total dose, age, fibrinogen, prothrombin time (PT), comorbidity, and concomitant use of voriconazole. Total dose, fibrinogen, PT, activated partial thromboplastin time, white blood cell count, and concomitant use of voriconazole were selected to predict hypofibrinogenaemia in patients with malignant haematologic diseases. Both models were calibrated adequately, and their predictions were correlated with the observed outcome. The cut-offs for treatment duration in the total population and the subgroup were 10 and 6 days, respectively.

CONCLUSIONS

Tigecycline in combination with voriconazole could increase the risk of hypofibrinogenaemia, and tigecycline-induced hypofibrinogenaemia is more likely to occur in patients with malignant haematologic diseases.

Metabolic characteristics of voriconazole - Induced liver injury in rats

Voriconazole (VOR) - induced liver injury is a common adverse reaction, and can lead to serious clinical outcomes. It is of great significance to describe the metabolic characteristics of VOR - induced liver injury and to elucidate the potential mechanisms. This study investigated the changes of plasma metabolic profiles in a rat model of VOR - induced liver injury by non - targeted metabolomics. Correlation analysis was performed between differentially expressed metabolites and plasma liver function indexes. The metabolites with strong correlation were determined for their predictive performance for liver injury using receiver operating characteristic (ROC) curve analysis. Potential biomarkers were then screened combined with liver pathological scores. Finally, the expression level of genes that involved in lipid metabolism were determined in rat liver to verify the mechanism of VOR - induced liver injury we proposed. VOR - induced liver injury in rats was characterized by plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) elevation, the lipid droplets accumulation in liver, as well as inflammation and fibrosis. Significant changes of plasma metabolites were observed, with a decrease in lipid metabolites accounting for over 50% of all changed metabolites, and alterations of cholesterol and bile acids metabolites. The decrease of 3 phosphatidylcholine (PC) in plasma could indicate the occurrence of VOR - induced liver injury. Decreased fatty acids (FA) oxidation and bile acid excretion might be the potential mechanisms of VOR - induced liver injury. This study provided new insights into the molecular characterization of VOR - induced liver injury.

Optimization of Voriconazole Dosing Regimens Against Aspergillus Species and Candida Species in Pediatric Patients After Hematopoietic Cell Transplantation: A Theoretical Study Based on Pharmacokinetic/Pharmacodynamic Analysis

This study aimed to optimize the dosing regimens of voriconazole (VRC) for pediatric patients after hematopoietic cell transplantation with different cytochrome P450 (CYP) 2C19 phenotypes and body weights, based on pharmacokinetic (PK)/pharmacodynamic (PD) analysis. The PK parameters of VRC were derived from previous literature. Combined with key factors affecting VRC, patients were categorized into 9 subgroups based on different CYP2C19 phenotypes (poor metabolizer/intermediate metabolizer, normal metabolizer, and rapid metabolizer/ultrarapid metabolizer) and typical body weights (15, 40, and 65 kg). Monte Carlo simulation was used to investigate dosing regimens for different groups. The area under the 24-hour free drug concentration-time curve to the minimum inhibitory concentration (MIC) > 25 was used as the target value for effective treatment. The probability of target achievement and the cumulative fraction of response were determined on the basis of the assumed MICs and MICs distribution frequency of Aspergillus species and Candida species. When the MIC was ≤1 mg/L, 4 mg/kg every 12 hours was sufficient for optimal effects in groups 1-3 and groups 5 and 6; however, 6 mg/kg every 12 hours was required for group 4, and 8 mg/kg every 12 hours was required for groups 7-9. In empirical treatment, lower (2-6 mg/kg every 12 hours) and higher (6-12 mg/kg every 12 hours) dosing regimens were recommended for Candida spp. and Aspergillus spp., respectively. Our findings will assist in selecting appropriate dosing regimens of VRC for pediatric patients after hematopoietic cell transplantation with different CYP2C19 phenotypes and body weights. Clinically, it is better to continuously adjust the dosing on the basis of the therapeutic drug monitoring.

Voriconazole-Induced Hepatotoxicity in a Patient with Pulmonary Aspergillosis: A Case Report

Voriconazole is the therapy of choice for aspergillosis. However, hepatotoxicity is the most common reason for the discontinuation of voriconazole. In contrast, posaconazole is well tolerated, with a low incidence of hepatotoxicity. In most cases, hepatotoxicity is associated with high voriconazole trough concentration influenced mainly by cytochrome P450 (CYP) 2C19 gene polymorphism. Compared with normal metabolizers, intermediate and poor metabolizers generally have higher voriconazole trough concentrations with an increased risk of hepatotoxicity. Here, we describe changes in hepatotoxicity throughout azole therapy in a patient with pulmonary aspergillosis (PA). Nevertheless, the patient with the normal metabolism genotype of CYP2C19 developed severe hepatotoxicity caused by voriconazole but tolerated posaconazole well, with a lack of direct cross-hepatotoxicity between the both. Interestingly, the patient had a high risk of hepatotoxicity at a low voriconazole trough concentration. Fortunately, elevated liver enzymes declined to the baselines with posaconazole treatment.

Development of a New Method for Simultaneous Quantitation of Plasma Concentrations of Voriconazole and Voriconazole N-Oxide Using Column-Switching LC-MS/MS and Its Application in Therapeutic Drug Monitoring

Background

Voriconazole therapy for fungal infections usually continues for several years and is often administered on an outpatient basis. Maintaining the voriconazole plasma concentration in the therapeutic range is highly important for effective therapy; however, it is difficult to obtain sufficient information to assess the voriconazole concentration in outpatients. Therefore, we developed a method to simultaneously measure the plasma concentrations of voriconazole and its major metabolite, voriconazole N-oxide, to obtain rapid results after outpatient blood collection and before medical consultation and to attain a better understanding of adherence and the drug-drug interactions of voriconazole.

Methods

Fifty microliters of patient plasma was deproteinized with methanol, injected into the liquid chromatography-tandem mass spectrometry system, and purified using an online column. Separation was achieved on an InertSustain C18 column (2.1 mm id × 50 mm, 2 μm) with a mobile phase of 30:70 (0.1% formic acid in water:methanol) at a flow rate of 0.2 mL/min. Detection was performed using electrospray ionization in positive ion multiple reaction monitoring mode.

Results

The analysis time was 4 min. The calibration curve was linear, in the range of 0.1 μg/mL to 20 μg/mL for voriconazole and 0.05 μg/mL to 10 μg/mL for voriconazole N-oxide, with a coefficient of determination at R2 > 0.999.

Conclusion

There is no need to dilute the patient's plasma even if the concentration of voriconazole is near the upper limit of measurement. Furthermore, the short measurement-time could immediately inform physicians of the patient's voriconazole concentration during ambulatory medical care. Simultaneous measurement of voriconazole and voriconazole N-oxide may also be useful for the immediate adjustment of voriconazole dosage in outpatients and would help us to understand adherence or drug-drug interactions in plasma voriconazole concentrations.