Sotalol dose optimization for fetal tachycardia: a pregnancy physiologically based pharmacokinetic model study.

ObjectiveTo establish an optimized sotalol dosing strategy for fetal tachycardia by using a pregnancy computational model for dose simulations. MethodsA physiologically-based computational model, including pregnancy-related changes and placental transfer values, was established and verified. Simulations of the current dosing advises and prospective dosing scenarios were performed. To avoid maternal dose-related toxicity (QT-prolongation) we aimed for maternal concentrations <2.5 mg/L. Based on neonatal concentration-effect data, we aimed for a fetal Ctrough concentrations of 0.4 - 1.0 mg/L. ResultsThe pregnancy physiologically-based pharmacokinetic model accurately predicted maternal and fetal exposures. Predictions indicate that almost 16% of maternal plasma concentrations exceed the toxic level of 2.5 mg/L at the maximum oral daily dose of 480 milligram, while 90% of fetuses have a Ctrough concentration within the therapeutic window. When lowering the maximum daily dose to 400 mg, 0.1% of maternal plasma concentrations exceed 2.5 mg/L, while 87% of the fetal plasma concentrations remain in the therapeutic window. Additionally dosing 480 mg in three times daily reduces the risk of high maternal plasma exposure to 0.3%, while maintaining effective fetal Ctrough concentrations in 95% of fetuses. ConclusionPregnancy computational modeling can be used to adequately predict maternal and fetal sotalol exposures. Our simulations suggest that daily doses should not exceed 400 milligram and that dividing the oral daily dose over three doses improves the balance between high maternal plasma exposure and effective fetal concentrations. FundingThis publication is based on research funded by the Bill & Melinda Gates Foundation (INV-023795).