Abstract
Objectives: The internal dose of ethyl parabens is important in order to evaluate the risk of this chemical. However, there are little PK model data for parabens to apply this. This experiment attempted PK modeling to ascertain PK values. Methods: Twenty mg/kg ethyl paraben was administered orally to Sprague-Dawley rats at the same point in time. The rats were sacrificed at times 0, 15, 30 and minutes, and 1, 2, 4, 8, 12, 24 hours after oral gavage. Blood and urine were collected and pretreated for analysis. Accuracy, precision and LOD (limit of detection) were calculated for this analysis. Ethyl paraben, detected by HPLC-MS, was applied to PK modeling using Berkeley Madonna. Results: This study showed 100.1-103.7% accuracy, 1.4-3.7% precision and a 1.0 ng/mL limit of detection. Orally administered ethyl paraben reached maximum concentration after 30 minutes of dosing in serum and urine of rats. The concentrations were 2,354 ng/mL in serum and 386,000 ng/mL in urine samples. These peak concentrations were excreted after one hour of intubation over 12 hours. For the pharmacokinetic parameters of ethyl paraben revealed using Berkeley Madonna, the absorption rate was 5.539/hour, the excretion rate was 0.048/hour, the half-life was 14.441 hours and AUC was 481,186 ng hour/mL. Conclusion: Orally administered ethyl paraben was absorbed rapidly in rats and excreted in urine. This chemical, ethyl paraben, accumulated in the body but was excreted over 12 hours after dosing.