FATE OF WATER-SOLUBLE POLYMERS ADMINISTERED VIA DIFFERENT ROUTES

The biological fate of synthetic water-soluble polymers administered t o mice by injection at different sites is described. After intraperito neal tip), subcutaneous (sc), and intramuscular (im) injections of (12 5)l-labeled poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) with various molecular weights, the time-course of polymer concentrati on in the blood was measured and analyzed pharmacokinetically. The loc ation of PVA in the body was similar to that of PEG; that is, the elim ination from the injection sites and the translocation from the inject ion sites into the blood circulation were similar for both polymers. T he elimination rate of both polymers from the injection sites increase d in the order ip > sc > im. After sc and im injections of polymers, t he elimination rate decreased with an increase in the molecular weight , whereas the elimination rate of polymers injected showed no molecula r weight dependence over the range studied, regardless of the type of polymers used. The time-course of polymer concentration in the blood d epended largely on the injection route of the polymers, and the polyme r elimination from the blood circulation was enhanced with the decreas ing molecular weight of polymers injected. It was concluded that the m olecular weight and the injection site are the important factors that affect the concentration profile of polymers in the blood circulation.