Blood coagulation is inhibited by sulphated copolymers of vinyl alcohol and acrylic acid under in vitro as well as in vivo conditions.

Biological effects of the modification of the sulphate ester and carboxyl group content of poly(vinyl alcohol-acrylic acid) copolymers (PAVAS) and sulphated polyvinyl alcohol copolymers (PVAS) with mol. weight of 5,000 to 20,000 D were studied. The in vitro anticoagulant potency of PAVAS assessed by activated partial thromboplastin time (APTT) increased with increasing the overall anionic charge, while differences in mol. weight yielded few obvious effect. The degree of sulphation played an essential part, but the carboxyl group content also contributed to the in vitro anticoagulant activity of PAVAS. On i.v. administration to rats (40 mg/kg), the anticoagulant potency of PAVAS was found to be comparable to that observed in vitro. The ability of PAVAS to induce a state of leukocytosis and decrease serum triglyceride level in rats was also dependent on charge density, and both these effects were increased with elevation of charged groups content irrespectively of mol. weight. Sulphated polyvinyl alcohol copolymers (PVAS) showed similarity to PAVAS charge-dependent biological activities.