Physiologically based pharmacokinetic modelling to optimize dosing regimen of biapenem in renal impairment and elderly populations

Objectives Biapenem is used to treat bacterial infections in various populations. However, no dosing recommendations exist for renal impairment and elderly populations. This study aimed to simulate the pharmacokinetics of biapenem in special populations using physiologically based pharmacokinetic (PBPK) modelling and to optimize dosing regimens. Methods A whole-body PBPK model for biapenem was developed and evaluated in healthy adults. Then the model was extrapolated to renal impairment and elderly populations. Box-whisker analysis and Monte Carlo simulation were performed to optimize the dosing regimen. Results The developed PBPK models incorporating glomerular filtration and hydrolase metabolism accurately characterized biapenem pharmacokinetics in healthy adults and in renal impairment and elderly populations. For moderate, severe and end-stage renal impairment populations, we recommend reducing the biapenem dose to 67%, 50% and 30% of that for healthy adults, respectively, to achieve comparable therapeutic efficacy. No dose adjustment is necessary for individuals with mild renal impairment. The elderly population with renal impairment should follow the same dosage adjustments as those recommended for general renal impairment. Against Escherichia coli and Klebsiella pneumoniae, most simulated dosage regimens achieved cumulative fraction of response (CFR) values exceeding 80% for targets of 40%, 60% and 80% of time that free drug concentrations exceed the minimum inhibitory concentration (%fT > MIC) in healthy adults and in renal impairment and elderly populations. However, none of the simulated regimens produced satisfactory CFR values against Pseudomonas aeruginosa or Acinetobacter baumannii in these populations. Conclusions Biapenem PBPK models were successfully developed to optimize dosing regimens for special populations.