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[Pharmacological studies of low molecular weight heparin (LHG)]
1Shimizu Pharmaceutical Co., Ltd., Research Department, Shizuoka, Japan.
The effects of low molecular weight heparin (LHG) on the blood coagulation system, hemorrhage, lipolytic activity and bone metabolism were compared with those of conventional sodium heparin (Heparin). The anti-thrombin activity of LHG measured by the prolongation of activated partial thromboplastin time and thrombin time and measured by the suppressive effect on thrombin-induced mortality was approximately 4 times weaker than those of Heparin on a weight basis, while the anti-Xa activity of LHG measured by the chromogenic method was approximately half of that of Heparin. Heparin caused a marked and dose-dependent increase in the rat-tail bleeding time, while the effect of LHG was almost 4 times weaker than that of Heparin. These results indicate that the prolongation of bleeding time is mainly due to the inhibition of thrombin. At low doses, LHG showed lower lipolytic activity than Heparin, while at high dosage, LHG and Heparin showed similar activity. Heparin enhanced the ADP-induced platelet aggregation in vitro, but LHG showed no effects. LHG and Heparin had no effects on bone resorption nor bone formation in the rat cultured calvaria. The results of our study suggest that alternate use of LHG may reduce the known adverse effects of conventional heparin.
The effects of low molecular weight heparin (LHG) on the blood coagulation system, hemorrhage, lipolytic activity and bone metabolism were compared with those of conventional sodium heparin (Heparin). The anti-thrombin activity of LHG measured by the prolongation of activated partial thromboplastin time and thrombin time and measured by the suppressive effect on thrombin-induced mortality was approximately 4 times weaker than those of Heparin on a weight basis, while the anti-Xa activity of LHG measured by the chromogenic method was approximately half of that of Heparin. Heparin caused a marked and dose-dependent increase in the rat-tail bleeding time, while the effect of LHG was almost 4 times weaker than that of Heparin. These results indicate that the prolongation of bleeding time is mainly due to the inhibition of thrombin. At low doses, LHG showed lower lipolytic activity than Heparin, while at high dosage, LHG and Heparin showed similar activity. Heparin enhanced the ADP-induced platelet aggregation in vitro, but LHG showed no effects. LHG and Heparin had no effects on bone resorption nor bone formation in the rat cultured calvaria. The results of our study suggest that alternate use of LHG may reduce the known adverse effects of conventional heparin.