Distribution and excretion of N-Ile1 Thr2-63-desulfatohirudin in rats

Objective To investigate distribution and excretion of N-Ile1Thr2-63-desulfatohirudin(rH)a recombinant hirudin newly developed in China,in rats for its development as a novel anticoagulant agent.Methods ELISA was used to determine the rH concentration in related tissues and body fluids.Tissues were collected at 15,60 and 180min respectively,after iv administration of rH 1.0 mg·kg-1 to 3 groups of 5 rats,and homogenized.Urine,bile and feces were collected at pre-selected intervals of time after iv dosing 1.0 mg·kg-1 to 3 groups of 5 rats and assayed.Results rH following iv dosing was distributed rapidly,the rH levels in all tissues being found to be the highest at 15 min post-injection,afterwards gradually reduced.The highest concentration of rH was found in blood,the next in lung and heart,the lowest in brain.With 15 min post dose as an example,the rH contents in tissues were ranked in order of plasma>lung>heart >adipose>skeletal muscles>kidney>liver>spleen>brain.The 12 h-cumulative excretion amount of rH in urine and feces accounted for 0.03%and 0.001% of administered dose,respectively;the 6 h-cumulative excretion amount in bile was 0.02%of the dose.Conclusions The rH is distributed mainly in blood circulation system with very low content in other tissues.The drug is excreted from urine,feces and bile of rats in extremely minute amount(only 0.051% dose),suggesting that rH undergoes extensive metabolic elimination in rat body.