Therapeutic drug monitoring
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The objectives of this study were to develop a population pharmacokinetic model and to determine the covariates affecting the pharmacokinetics of busulfan in Japanese pediatric patients who received high-dose oral busulfan as a conditioning regimen before hematopoietic stem cell transplantation. Population analysis was performed using retrospective therapeutic drug monitoring data (including test dose data) from 103 children. Their ages ranged from 2 months to 11 years old (mean age, 30 months; median age, 18 months). ⋯ The busulfan formulation (1% powder form or crystal form) and dose (milligrams per kilogram) influenced the absorption rate constant. It was estimated that oral clearance expressed per kilogram of body weight is low at early infancy, then increases to a maximum at approximately 2 years of age and, thereafter, decreases. In conclusion, we have developed a population pharmacokinetic model of oral busulfan in children, particularly for those younger than 4 years old, that takes into consideration not only body size, but also several other covariates.
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In critically ill patients, dosage adjustment of voriconazole could be helpful when high-volume continuous venovenous hemofiltration is needed. Voriconazole pharmacokinetics were studied in an anuric critically ill patient, under high-volume continuous venovenous hemofiltration, over an interval period after a 4-mg/kg dose of voriconazole. Arterial and effluent voriconazole concentrations were measured after liquid phase extraction using a high-pressure liquid chromatography. ⋯ High-volume continuous venovenous hemofiltration could affect voriconazole disposition in contrast with other techniques. Besides, we observed voriconazole accumulation consequence of the saturation of the metabolic clearance resulting from multiple organ failure. Dosage adjustment seems to be required in these conditions, but this observation must be confirmed by a clinical study.