[Pharmacokinetics of a long-circulating PEGylated Radix Ophiopogonis polysaccharide]

The pharmacokinetics of a long-circulating PEGylated Radix Ophiopogonis polysaccharide (ROP) was investigated in rats following i.v. or s.c. administration at three dose levels (9, 20, 50 mg x kg(-1)). A moderate coupling reaction between the hydroxyl-activated ROP and the amino-terminated mPEG was chosen to produce PEGylate ROP. The grafting degree of the prepared conjugate was 1.03, and the molecular mass of mPEG used was 20 kDa. High-performance gel permeation chromatorgraphy with fluorescein isothiocyanate prelabeling was established to determine levels of the conjugate in plasma. The results showed that the elimination half-life of the conjugate following s.c. administration was basically identical to that after iv administration. An accurate linear correlation was observed between administration doses and areas under the curve of plasma conjugate level vs. time profile, regardless of the administration route. The absolute bioavailability of the conjugate following sc administration was approximately 56%, and the mean in vivo residence time was 52.1 h, increased 2.4 times compared to those of iv administration. In general, linear pharmacokinetics was observed for the conjugate within the dose range studied, and sc should be a promising administration route for the conjugate.