Purpose: Various blood collection methods were developed and used in the pharmacokinetic evaluation of drugs. However, the influence of different blood sampling methods on plasma drug concentrations has not been clarified. In the present study, we aimed to determine whether the plasma concentration of a target drug changes based on the collection site and elucidate the mechanism responsible for this change.
Methods: We compared three blood sampling methods commonly used in small animals. Eight clinical drugs were selected and administered to rats simultaneously via intracardiac injection or oral gavage. Blood samples were collected from different sites at the same individual, and pharmacokinetic properties of the drugs were then evaluated.
Results: Study results showed that the maximum plasma concentration or area under the curve of three study drugs was significantly higher in rats when blood was sampled from the carotid artery than when it was sampled from the caudal vein or by tail snip.
Conclusions: Pharmacokinetics of certain drugs may differ based on the blood sampling site. The acid-base properties of drugs may influence pharmacokinetic evaluation. The rate and extent of drug distribution may also cause such differences and have significant effects on plasma drug levels.
Keywords: blood sampling; carotid cannulation; caudal vein; pharmacokinetics; tail snip.