Berg, Alexander

AbstractThe population pharmacokinetic model reported here was developed using data from 2 phase 2 trials of irinotecan for treatment of malignant glioma to quantify the impact of concomitant therapy with enzyme‐inducing antiepileptic drugs (EIAEDs) on irinotecan pharmacokinetics. Patients received weekly irinotecan doses of 100 to 400 mg/m2, and plasma samples were collected and analyzed for irinotecan and its APC, SN‐38, and SN‐38G metabolites. Nonlinear mixed‐effects modeling was employed for population pharmacokinetic analysis. Concomitant therapy with phenytoin, phenobarbital, or carbamazepine increased the clearances of irinotecan, SN‐38, and SN‐38G but not APC. SN‐38 clearance was 2‐fold higher with concomitant EIAED use, resulting in 40% lower SN‐38 exposure. Evaluation of additional covariates revealed no clinically relevant effects of sex or concomitant corticosteroid use. The population pharmacokinetic model suggests that a 1.7‐fold increase in irinotecan dose may compensate for decreases in SN‐38 exposure in the presence of concomitant EIAEDs. Although slightly more conservative, this dose adjustment is consistent with those recommended based on increases in the maximally tolerated dose for malignant glioma patients receiving EIAEDs and may be an appropriate starting point for further investigation when extrapolating to other cancer types or alternative regimens.

AbstractSulindac is a prescription‐based non‐steroidal anti‐inflammatory drug (NSAID) that continues to be actively investigated as a candidate cancer chemoprevention agent. To further current understanding of sulindac bioavailability, metabolism, and disposition, we developed a population pharmacokinetic model for the parent compound and its active metabolites, sulindac sulfide, and exisulind. This analysis was based on data from 24 healthy subjects who participated in a bioequivalence study comparing two formulations of sulindac. The complex disposition of sulindac and its metabolites was described by a seven‐compartment model featuring enterohepatic recirculation and is the first reported population pharmacokinetic model for sulindac. The derived model was used to explore effects of clinical variables on sulindac pharmacokinetics and revealed that body weight, creatinine clearance, and gender were significantly correlated with pharmacokinetic parameters. Moreover, the model quantifies the relative bioavailability of the sulindac formulations and illustrates the utility of population pharmacokinetics in bioequivalence assessment. This novel population pharmacokinetic model provides new insights regarding the factors that may affect the pharmacokinetics of sulindac and the exisulind and sulindac sulfide metabolites in generally healthy subjects, which have implications for future chemoprevention trial design for this widely available agent.