Fluconazole In Infants Research Articles

Clinical pharmacology of fluconazole in infants and children

Clinical pharmacology of fluconazole in infants and children

External Evaluation of Two Fluconazole Infant Population Pharmacokinetic Models.

Fluconazole is an antifungal agent used for the treatment of invasive candidiasis, a leading cause of morbidity and mortality in premature infants. Population pharmacokinetic (PK) models of fluconazole in infants have been previously published by Wade et al. (Antimicrob Agents Chemother 52:4043-4049, 2008, https://doi.org/10.1128/AAC.00569-08) and Momper et al. (Antimicrob Agents Chemother 60:5539-5545, 2016, https://doi.org/10.1128/AAC.00963-16). Here we report the results of the first external evaluation of the predictive performance of both models. We used patient-level data from both studies to externally evaluate both PK models. The predictive performance of each model was evaluated using the model prediction error (PE), mean prediction error (MPE), mean absolute prediction error (MAPE), prediction-corrected visual predictive check (pcVPC), and normalized prediction distribution errors (NPDE). The values of the parameters of each model were reestimated using both the external and merged data sets. When evaluated with the external data set, the model proposed by Wade et al. showed lower median PE, MPE, and MAPE (0.429 μg/ml, 41.9%, and 57.6%, respectively) than the model proposed by Momper et al. (2.45 μg/ml, 188%, and 195%, respectively). The values of the majority of reestimated parameters were within 20% of their respective original parameter values for all model evaluations. Our analysis determined that though both models are robust, the model proposed by Wade et al. had greater accuracy and precision than the model proposed by Momper et al., likely because it was derived from a patient population with a wider age range. This study highlights the importance of the external evaluation of infant population PK models.

Population Pharmacokinetics of Fluconazole in Premature Infants with Birth Weights Less than 750 Grams.

Fluconazole is an effective agent for prophylaxis of invasive candidiasis in premature infants. The objective of this study was to characterize the population pharmacokinetics (PK) and dosing requirements of fluconazole in infants with birth weights of <750 g. As part of a randomized clinical trial, infants born at <750 g birth weight received intravenous (i.v.) or oral fluconazole at 6 mg/kg of body weight twice weekly. Fluconazole plasma concentrations from samples obtained by either scheduled or scavenged sampling were measured using a liquid chromatography-tandem mass spectrometry assay. Population PK analysis was conducted using NONMEM 7.2. Population PK parameters were allometrically scaled by body weight. Covariates were evaluated by univariable screening followed by multivariable assessment. Fluconazole exposures were simulated in premature infants using the final PK model. A population PK model was developed from 141 infants using 604 plasma samples. Plasma fluconazole PK were best described by a one-compartment model with first-order elimination. Only serum creatinine was an independent predictor for clearance in the final model. The typical population parameter estimate for oral bioavailability in the final model was 99.5%. Scavenged samples did not bias the parameter estimates and were as informative as scheduled samples. Simulations indicated that the study dose maintained fluconazole troughs of >2,000 ng/ml in 80% of simulated infants at week 1 and 59% at week 4 of treatment. Developmental changes in fluconazole clearance are best predicted by serum creatinine in this population. A twice-weekly dose of 6 mg/kg achieves appropriate levels for prevention of invasive candidiasis in extremely premature infants.

Pharmacokinetics and Safety of Fluconazole in Young Infants Supported With Extracorporeal Membrane Oxygenation

Candida infections are a leading cause of infectious disease-related death in infants supported with extracorporeal membrane oxygenation (ECMO). The ECMO circuit can alter drug pharmacokinetics; thus, standard fluconazole dosing in children on ECMO may result in suboptimal drug exposure. This study determined the pharmacokinetics of fluconazole in infants on ECMO. Infants <120 days of age received either intravenous fluconazole prophylaxis (25 mg/kg once a week) or treatment (12 mg/kg daily) while on ECMO. Paired plasma samples were collected preoxygenator and postoxygenator around doses 1 and 2 to calculate pharmacokinetic indices and describe oxygenator extraction. A 1-compartment model was fit to the data using nonlinear regression. Surrogate pharmacodynamic targets for efficacy were evaluated. Ten infants were enrolled. After dose 1 (n = 9), the median clearance was 17 mL/kg/h, the median volume of distribution was 1.5 L/kg and the median exposure in the first 24 hours (area under the curve from 0 to 24 hours) was 322 h × mg/L. After multiple doses (n = 7), the median clearance was 22 mL/kg/h, the median volume of distribution was 1.9 L/kg and the area under the curve from 0 to 24 hours was 352 h × mg/L. After dose 1, 78% of infants achieved the prophylaxis target, whereas only 11% achieved the therapeutic target. Oxygenator extraction of fluconazole was minimal (-2.0%, standard deviation 15.0), and extraction was not correlated with age of the ECMO circuit (ρ= -0.05). There were no adverse events related to fluconazole. Infants on ECMO had higher volume of distribution but similar clearance when compared with historical controls not on ECMO. In infants on ECMO, a fluconazole dose of 25 mg/kg weekly provides adequate exposure for prophylaxis against Candida infections. However, higher doses may be needed for treatment.

Pharmacokinetics of fluconazole in children requiring peritoneal dialysis

After major open heart surgery, a significant number of infants and children are dependent on peritoneal dialysis as a result of renal impairment. They often require broad-spectrum antibiotics for the treatment of ongoing infections or as prophylactic therapy and have an increased risk of fungal infection. Fluconazole is a new thiazole antifungal agent that has been widely used in adults, but its use in children with acute renal impairment requiring peritoneal dialysis has not been documented. The purpose of this investigation was to study the pharmacokinetics of fluconazole in infants and children who developed various degrees of renal impairment, with or without the need for peritoneal dialysis, after major open heart surgery. Between January 1992 and June 1995, 17 children ranging in age from 2 weeks to 3 years (mean, 6 months) who received fluconazole therapy intravenously (3 mg/kg per day for 2 to 3 weeks) after major open heart surgery were enrolled in a prospective study. They were divided into two groups—those who required peritoneal dialysis (PD group; n = 8) and those who did not (non-PD group; n = 9). Blood, urine, and peritoneal dialysate samples were collected for 4 days to determine the pharmacokinetics of the drug, and data were compared between the two groups. The two groups of children had similar demographic characteristics, and their plasma concentrations of fluconazole showed no statistically significant differences. For children dependent on peritoneal dialysis, fluconazole was excreted almost solely through dialysis. Despite a significantly longer terminal elimination half-life for this group of infants, they tended to have a marginally larger volume of distribution of the drug. This, coupled with the continuous hourly exchange of dialysate, provided a large sink volume to effectively remove fluconazole from the circulation. Thus the plasma clearance and the accumulation ratio were comparable for the two groups of children. Continuous cycling peritoneal dialysis effectively removed fluconazole from the circulation and was the main mode of excretion of the drug in children dependent on dialysis.