A retrospective analysis of voriconazole pharmacokinetics in Japanese pediatric and adolescent patients

Voriconazole in the treatment of pediatric patients with hematologic malignancies and invasive fungal infections: a real-world study

PURPOSE

To evaluate the factors influencing voriconazole (VRC) administration, clinical efficacy, and safety in children with hematological malignancies (HM) and invasive fungal infection (IFD).

METHODS

This is a single-center, retrospective real-world study conducted between July 2018 and December 2023. Univariate and multivariate logistic regression analysis were used to analyze the affecting factors.

RESULTS

A total of 167 patients were included in this study. Among them, 13.77% (23/167) of children under 2 years old received off-label use of VRC, with an initial maintenance dose higher than that of other groups (P < 0.001). There were 8 cases (4.79%) of cured, 148 cases (88.62%) of improved, and 11 cases (6.59%) of ineffective. Thirty-eight cases experienced adverse drug reactions (ADR), with a highest incidence (10.2%) of hepatotoxicity. The concomitant proton pump inhibitors (PPIs), days of central venous catheterization and coagulopathy were independent influencing factors of ADR. Sixty-six patients underwent therapeutic drug monitoring (TDM), which increased the probability of achieving the target plasma trough concentration (Cmin). Among children < 2 years old underwent TDM, 88.89% (8/9) achieved therapeutic concentration, and the probability was higher than that of the older groups. Days of VRC treatment had a positive but not statistically significant effect on achievement of target Cmin. Hypoalbuminemia and days of antimicrobials treatment were independent influencing factors of Cmin distribution.

CONCLUSION

Attention to the off-label use of VRC in children < 2 years old, hypoalbuminemia and coagulopathy correction, potential drug interactions with VRC, and ADR monitoring is crucial for clinical efficacy and safety.

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.

Therapeutic Drug Monitoring of Voriconazole in Critically Ill Pediatric Patients: A Single-Center Retrospective Study

BACKGROUND AND OBJECTIVE

Voriconazole pharmacokinetics are highly variable in pediatric patients, and the optimal dosage has yet to be determined. The purpose of this study was to describe voriconazole pharmacokinetic and pharmacodynamic targets achieved and evaluate the efficacy and safety of voriconazole for critically ill pediatrics.

METHODS

This is a single-center retrospective study conducted at a pediatric intensive care unit at a tertiary/quaternary hospital. Pediatrics admitted to the pediatric intensive care unit and who received voriconazole for a proven or suspected fungal infection with at least one measured trough concentration were included. The primary outcomes included the percentage of pediatric patients who achieved the pharmacokinetic and pharmacodynamic targets. Secondary outcomes included assessing the correlation between voriconazole trough concentrations and clinical/microbiological outcomes. All statistical analyses were performed using the R statistical software and Microsoft Excel. Multiple logistic regression was used to assess the predictors of both clinical and microbiologic cures. Multiple linear regression was used to determine significant factors associated with trough concentrations.

RESULTS

A total of 129 voriconazole trough concentrations were measured from 71 participants at steady state after at least three doses of voriconazole. The mean (± standard deviation) of the first and second trough concentrations were 2.9 (4.2) and 2.3 (3.3) mg/L, respectively. Among the first trough concentrations, only 33.8% were within the therapeutic range (1-5 mg/L), 46.5% were below the therapeutic range, and 19.7% were above the therapeutic range. A clinical cure occurred in 78% of patients, while a microbiologic cure occurred in 80% of patients.

CONCLUSIONS

Voriconazole trough concentrations vary widely in critically ill pediatric patients and only a third of the patients achieved therapeutic concentrations with initial doses.

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

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

Voriconazole monitoring in children with invasive fungal infections

OBJECTIVES

The primary objective of this study was to determine the optimal daily dose of voriconazole required to achieve therapeutic trough concentrations in children 1 month to 18 years of age. The secondary objective was to analyze the association between voriconazole trough concentrations and clinical and microbiological outcomes, toxicity, and mortality.

METHODS

This study was a retrospective chart review (October 2009 to August 2012) of pediatric oncology/bone marrow transplant patients with proven or probable invasive fungal infections treated with intravenous or oral voriconazole. Patients were excluded if they were older than 18 years of age, had no voriconazole concentrations drawn during the study period, or received voriconazole prior to the study period.

RESULTS

Thirty-four patients were reviewed; 11 patients met all criteria for inclusion. There were 6 males and 5 females, with a median age of 8 years (range: 0.8-14.8) and a median weight of 27 kg (range: 9-74). Doses were adjusted to a median 6 mg/kg/dose (range: 3-8.7 mg/kg/dose) given every 8 (n = 5) to 12 (n = 6) hours; dose regimens varied greatly. All but 1 child achieved a voriconazole trough concentration above 1 mg/L; 7 children had a trough concentration above 2 mg/L. The median time to achieve a therapeutic trough concentration was 11 days (range: 6-37 days). Therapy failed for 4 of 11 patients, including 3 of the 4 youngest patients (p=0.022). Three of the 4 for whom therapy failed also had voriconazole trough concentrations less than 2 mg/L; this did not reach statistical significance. Voriconazole therapy was discontinued in 2 patients due to toxicity.

CONCLUSIONS

This study confirmed that voriconazole pharmacokinetics vary greatly in pediatric oncology/bone marrow transplant patients. "Optimal" doses varied over nearly a 3-fold range. Younger patients may be at greater risk of poor outcomes and may require additional monitoring and dose adjustment.

Pharmacokinetics and safety of voriconazole intravenous-to-oral switch regimens in immunocompromised Japanese pediatric patients

The aim of this study was to investigate the pharmacokinetics, safety, and tolerability of voriconazole following intravenous-to-oral switch regimens used with immunocompromised Japanese pediatric subjects (age 2 to <15 years) at high risk for systemic fungal infection. Twenty-one patients received intravenous-to-oral switch regimens based on a recent population pharmacokinetic modeling; they were given 9 mg/kg of body weight followed by 8 mg/kg of intravenous (i.v.) voriconazole every 12 h (q12h), and 9 mg/kg (maximum, 350 mg) of oral voriconazole q12h (for patients age 2 to <12 or 12 to <15 years and <50 kg) or 6 mg/kg followed by 4 mg/kg of i.v. voriconazole q12h and 200 mg of oral voriconazole q12h (for patients age 12 to <15 years and ≥50 kg). The steady-state area under the curve over the 12-h dosing interval (AUC0-12,ss) was calculated using the noncompartmental method and compared with the predicted exposures in Western pediatric subjects based on the abovementioned modeling. The geometric mean (coefficient of variation) AUC0-12,ss values for the intravenous and oral regimens were 51.1 μg · h/ml (68%) and 45.8 μg·h/ml (90%), respectively; there was a high correlation between AUC0-12,ss and trough concentration. Although the average exposures were higher in the Japanese patients than those in the Western pediatric subjects, the overall voriconazole exposures were comparable between these two groups due to large interindividual variability. The exposures in the 2 cytochrome P450 2C19 poor metabolizers were among the highest. Voriconazole was well tolerated. The most common treatment-related adverse events were photophobia and abnormal hepatic function. These recommended doses derived from the modeling appear to be appropriate for Japanese pediatric patients, showing no additional safety risks compared to those with adult patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01383993.).