Abstract
Heparin has been widely used as a potent anticoagulant for several decades and the mechanism of the action has almost been fully elucidated by recent aggressive biochemical investigation. The mode of administration of heparin, however, has not fully established yet, although various methods has been advocated such as bolus intravenous (i. v. bolus), continuous intravenous (i. v. cont.) or subcutaneous injection.
In the present study, the anticoagulant effect of heparin in rats was monitored and compared, employing different modes of administration. It was possible to maintain constant hypocoagulability by a combination of i. v. bolus and i. v. cont. but dosing was extremely difficult. A subcutaneous administration produced constant hypocoagulability of relatively longer duration compared with i. v. bolus or i. v. cont. Also, inhibitory effect on disseminated intravascular coagulation (DIC) in rats was studied with different methods of administratlon. The inhibition by heparin on DIC in rats was totally dependent upon the degree of hypocoagulability before DIC was triggered, regardless of the mode of administratlon. Clinically, subcutaneous administration of heparin was applied in 8 cases for the prevention and treatment of DIC and in 6 cases for those of thromboembolic diseases. The clinical dose of subcutaneous heparin was too small to be detected by conventional coagulation tests but overall clinical results were favorable, especially for the prevention of DIC, though number of patients was very limited. More extensive clinical trials are required to confirm the efficacy of subcutaneous heparin for the prevention of DIC but subcutaneous administration of heparin is also promising in other cases requiring mild hypocoagulability than in well documented effect in the prevention of postoperative deep vein thrombosis or pulmonary embolism.
