Pharmacokinetics and disposition study of calf thymus DNA in rats by applying 3H-labeling method

A tritium((3)H)-labeling method with high specificity was established to investigate the pharmacokinetics and disposition of the calf thymus DNA (ctDNA) in rats. The plasma pharmacokinetics, tissue distribution, mass balance and excretion were characterized in SD rats, respectively. Rats were injected i.v. with radiolabeled ctDNA with the dose of 40μCi/kg in each independent experiment. (3)H-labeled ctDNA was eliminated rapidly in plasma, with the half-life estimated from 9 to 13h and preferentially accumulated in liver and lung, its concentration in all the tissues investigated decreased to very low level after 24h. ctDNA exhibited 80.8% accumulative recovery, excretion of radiolabel in urine and bile was nearly complete by 72h, which shown as the main excretion pathways, and the total recovery of excretion reached 77.9% within three days. In conclusion, ctDNA was rapidly eliminated in plasma and would not accumulate in tissues, parent ctDNA and its radioactive metabolites can be recovered almost completely in schedule time. All the results indicated that the in vitro use of ctDNA is safe and will not bring out potential risk.