Abstract
PURPOSE: Parathyroid hormone (PTH) can induce the downregulation of CYP3A in chronic kidney disease (CKD). Nevertheless, the effect of PTH on CYP3A-mediated clearance pathways from a clinical perspective remains unclear. METHODS: This study employed population pharmacokinetic (PopPK) modeling to delineate potential changes in CYP3A activity in patients with CKD. Pharmacokinetic data for nifedipine, a typical CYP3A substrate, as well as covariate information, were prospectively collected from 157 patients with a total of 612 concentrations. PopPK data analysis was performed using a nonlinear mixed-effects model. RESULTS: The pharmacokinetics of nifedipine were optimally described according to a one-compartment model with zero-order absorption and first-order elimination. The estimated population parameters (and interindividual variability) were apparent clearance (CL/F) 49.61 L/h (58.33%) and apparent volume of distribution (V/F) 2300.26 L (45.62%), and the PTH level negatively correlated with CL/F. In comparison with the reference level, it was observed that the dosage of nifedipine should be reduced with the maximum boundary value of PTH, after a Monte Carlo simulation. CONCLUSION: This study provides insight into the effects of PTH on CYP3A-mediated clearance pathways. Moreover, PTH could be used as a guide for the appropriate administration of CYP3A eliminated drugs in patients with CKD.