Medical College of Wisconsin
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Hydroxycarbamide in children with sickle cell anaemia after first-dose vs. chronic therapy: pharmacokinetics and predictive models for drug exposure. Br J Clin Pharmacol 2018 Jul;84(7):1478-1485 PMID: 28884840 PMCID: PMC6005595

Pubmed ID

28884840

DOI

10.1111/bcp.13426

Abstract

AIMS: The purposes of this work were to: (1) compare pharmacokinetic (PK) parameters for hydroxycarbamide in children receiving their first dose (HC ) vs. those receiving chronic therapy (HC ), (2) assess the external validity of a published PK dosing strategy, and (3) explore the accuracy of dosing strategies based on a limited number of HC measurements.

METHODS: Utilizing data from two prospective, multicenter trials of hydroxycarbamide (Pharmacokinetics of Liquid Hydroxyurea in Pediatric Patients with Sickle Cell Anemia; NCT01506544 and Single-Dose (SD) and Steady-State (SS) Pharmacokinetics of Hydroxyurea in Children and Adolescents with Sickle Cell Disease), plasma drug concentration vs. time profiles were evaluated with a model independent approach in the HC and HC groups. Various predictive scenarios were analysed to evaluate whether systemic exposure with hydroxycarbamide could be accurately predicted.

RESULTS: Absorption of hydroxycarbamide was rapid, variable and dose independent. Dose-normalized peak plasma concentrations and drug exposure (AUC) were higher, and weight-normalized apparent oral clearance was lower in the HC group. We assessed a PK-guided dosing strategy along with other predictive scenarios and found that inclusion of plasma samples only slightly improved the accuracy of AUC predictions when compared to a population-based method.

CONCLUSIONS: Children naïve to hydroxycarbamide exhibit a different PK profile compared to children receiving chronic therapy. Accuracy of population-based dosing is sufficient to target AUCs in individual patients. Further clearance/bioavailability studies are needed to address the factors responsible for variability in the disposition of hydroxycarbamide.

Author List

Estepp JH, Wiczling P, Moen J, Kang G, Mack JM, Liem R, Panepinto JA, Garg U, Kearns G, Neville KA

Author

Julie A. Panepinto MD, MSPH Professor in the Pediatrics department at Medical College of Wisconsin




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