Abstract
Fibrinogen γ-chain (dodecapeptide HHLGGAKQAGDV, H12)-coated, adenosine-diphosphate (ADP)-encapsulated liposomes (H12-(ADP)-liposomes) were developed as a synthetic platelet alternative that specifically accumulates at bleeding sites as the result of interactions with activated platelets via GPIIb/IIIa and augments platelet aggregation by releasing ADP. The aim of this study is to characterize the pharmacokinetic properties of H12-(ADP)-liposomes and structural components in rats, and to predict the blood retention of H12-(ADP)-liposomes in humans. With use of H12-(ADP)-liposomes in which the encapsulated ADP and liposomal membrane cholesterol were radiolabled with 14C and 3H, respectively, it was found that the time courses for the plasma concentration curves of 14C and 3H radioactivity showed that the H12-(ADP)-liposomes remained intact in the blood circulation for up to 24 h after injection, and were mainly distributed to the liver and spleen. However, the 14C and 3H radioactivity of H12-(ADP)-liposomes disappeared from organs within 7 day after injection. The encapsuated ADP was metabolized to allantoin, which is the final metabolite of ADP in rodents, and was mainly eliminated in the urine, while the cholesterol were mainly eliminated in feces. In addition, the half-life of the H12-(ADP)-liposomes in humans was predicted to be approximately 18 hrs from pharmacokinetic data obtained for mice, rats and rabbits using an allometric equation. These results suggest that H12-(ADP)-liposome has a potential with proper pharmacokinetic and acceptable biodegradable properties as synthetic platelet substitute.
- The American Society for Pharmacology and Experimental Therapeutics