Abstract 4680: Effect of various anticoagulants on the bioanalysis of drugs in rat blood: Implications for pharmacokinetic studies of anticancer drugs
Authors: Kulkarni Preeti , Pathak Kamal , Gurjar Murari , Dhoble Sagar , Naik Arvind , Gavitre Bhaskar , Vidhun Bhaskar , Gota Vikram 
Published: May 2015

Abstract
Background: Pharmacokinetic studies play a vital role in the development and optimization of drugs, more so in cancer. Most often, pharmacokinetic blood samples are collected in EDTA vacutainers. Heparin is used infrequently and citrate, hardly ever. While the choice of anticoagulant is based on scientific rationale for some drugs, it is arbitrary in most others, with EDTA being the choice by convention. The purpose of this study was to evaluate the effects of anticoagulants on the bioanalysis of drugs.
Methods: Six drugs used extensively in cancer therapy / care were selected. Albino wistar rats (N=6 per drug) were dosed with one of the following drugs intraperitoneally - Pemetrexed (50mg/kg), Imatinib (50mg/kg), Erlotinib (25mg/kg), Meropenem (60mg/kg), 6-Mercaptopurine (20mg/kg) and Voriconazole (6mg/kg). Animals were sacrificed 2 hours after dosing (1 hour in 6-mercaptopurine group due to short half-life) by terminal bleeding from the retro-orbital plexus. Approximately 750 µL of blood was collected in each of Na2ETDA, heparin, trisodium citrate (TSC) and plain (no anticoagulant) tubes. Blood levels of the drug were determined by HPLC assay.
Results: Table below summarizes the findings of the study. Anticoagulant effect was significant for 3 out of 6 drugs. Concentration of erlotinib and meropenam were significantly underestimated when heparin was used, whereas EDTA led to underestimation of 6-mercaptopurine levels. Anticoagulants did not have any effect on the estimation of voriconazole levels. High interanimal variability in imatinib and pemetrexed levels did not allow adequate evaluation of the anticoagulant effect, although large differences in the average concentration of drugs were observed.
Conclusion: Careful selection of anti-coagulant is necessary for accurate characterization of pharmacokinetics of anticancer drugs. EDTA as the anticoagulant of choice is questionable and may lead to erroneous interpretation of pharmacokinetic data.
Effect of anticoagulant on the estimation of drug concentration in rat blood (Conc. in µg/mL)DrugHeparin(Mean±SD)EDTA(Mean±SD)TSC(Mean±SD)Plain(Mean±SD)P value (ANOVA)Imatinib5.74±4.406.75±5.207.37±6.946.45±4.47NSErlotinib0.85±0.841.24±0.951.97±1.081.12±0.91&lt;0.056-mercaptopurine0.31±0.170.21±0.120.26±0.100.42±0.24&lt;0.05Voriconazole2.19±0.872.32±0.872.14±0.842.44±1.09NSMeropenam0.37±0.130.52±0.130.49±0.110.51±0.14&lt;0.05Pemetrexed8.46±5.979.08±7.038.11±5.3010.39±7.60NS
Citation Format: Preeti Kulkarni, Kamal Pathak, Murari Gurjar, Sagar Dhoble, Arvind Naik, Bhaskar Gavitre, Bhaskar Vidhun, Vikram Gota. Effect of various anticoagulants on the bioanalysis of drugs in rat blood: Implications for pharmacokinetic studies of anticancer drugs. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4680. doi:10.1158/1538-7445.AM2014-4680