Abstract: Objective To evaluate the effects on hematology and serum chemistry parameters after single or multiple blood collection from the tail vein of rats, and to investigate whether blood collection for toxicokinetic analysis can be performed on the same animals from the main study rats or recovery rats in toxicity studies. Methods Fifty Sprague Dawley rats were randomly divided into 5 groups (5 per gender per group). Two models were used in this study. In Model 1 (imitating a single dose toxicity study), there are two groups including no blood sampling group and multiple blood sampling group. In Model 2 (imitating a 28-day toxicity study), there are three groups including no blood sampling group, single blood sampling group and multiple blood sampling group. Blood was collected via an abdominal artery to evaluate the effects on hematology and serum chemistry parameters on Day 2 (Model 1) and Day 29 (Model 2) respectively. Results Hematology and serum chemistry parameters were not affected in the male rats in Model 1 after multiple blood sampling and in both male and female rats in Model 2 after single blood sampling. However, erythrocyte parameters were affected in the female rats in Model 1 and in both genders in Model 2 after multiple blood sampling. Changes in several serum parameters were also noted in the rats in Model 2 after multiple blood sampling. Conclusion In rat toxicity studies, there is a possibility to perform multiple toxicokinetic blood sampling on the main study rats or on the recovery rats if the total blood loss can be controlled within a certain time interval.

Key words: Multiple blood collection, Rats, Hematology, Serum chemistry