Effect of Moderate Malnutrition on the Pharmacokinetics of Etoposide and Vincristine in Freshly Weaned Rats.

Background: Moderate malnutrition is a common problem in young children. It is observed that severe malnutrition affects the pharmacokinetics of chemotherapy drugs in pediatric cancer patients, but moderate malnutrition is not well studied in this context.

Objectives: In this study, we aimed to understand how moderate malnutrition affects the pharmacokinetics of two chemotherapy drugs, etoposide and vincristine, using a murine model of early age moderate malnutrition.

Methods: We developed a murine model of moderate childhood malnutrition by subjecting freshly weaned Sprague-Dawley rats to 8% protein diet for 8 weeks. In two separate experiments, we administered etoposide and vincristine (N = 8 for etoposide and N = 12 for vincristine each in protein deficient and control groups) through tail vein injection for pharmacokinetics study.

Results: We found ~ 60% increase in area under the concentration-time curve (AUC) of etoposide in malnourished animals as compared to well-nourished animals. Furthermore, clearance, volume of distribution, and half-life were decreased by ~ 37, 53, and 24%, respectively, in malnourished animals. Pharmacokinetic parameters of vincristine showed only marginal differences between well-nourished and malnourished groups.

Conclusions: Our results suggest that while moderate malnutrition significantly affects the pharmacokinetics of etoposide, pharmacokinetics of vincristine remain unchanged. Since chemotherapy drugs have a narrow therapeutic index, the difference in AUC observed in our study might explain the increased toxicity of etoposide in malnourished pediatric cancer patients. This brings forth a need for robust clinical studies to validate our findings and optimize dose for malnourished patients.