Bioavailability study of tetramethylpyrazine long-circulating and conventional liposomes in rats

Objective To study the pharmacokinetics and relative bioavailability of tetramethylpyrazine longcirculating liposomes and tetramethylpyrazine conventional liposomes in rats. Methods 12 rats were randomly divided into two groups. Single dose of tetramethyl-pyrazine long-circulating liposomes and tetramethylpyrazine conventional liposomes were intravenously administrated to the rats respectively. The tetramethylpyrazine concentration in plasma was determined by HPLC,and the pharmacokinetic parameters were calculated and analyzed by DAS 2. 1 and SPSS13. 0 software. Results The pharmacokinetics of tetramethylpyrazine longcirculating liposomes and tetramethylpyrazine conventional liposomes in rats were both accord with the two compartment models,The main pharmacokinetic parameters were as follows: t1/2β(7. 56 ±1. 53) h and(0. 07 ± 0. 05) h,MRT0-∞(5. 57 ±1. 76) h and(2. 96 ±1. 04) h,AUC0-∞(24. 64 ±1. 30) mg·L-1·h and(7. 58 ±0. 95) mg·L-1·h,there were significantly differences between two preparations. And the relative bioavailability of tetramethylpyrazine long-circulating liposomes to tetramethylpyrazine conventional liposomes was(325. 07 ± 10. 2) %. Conclusion Compared with tetramethylpyrazine common liposomes,tetrame-thylpyrazine longcirculating liposomes have longer release time and higher bioavailability.