How long after your last dose does Fragmin continue to have blood thinning effects? ## The active ingredient in Fragmin Graduated Syringes is dalteparin sodium. Each syringe contains 10,000 IU (units) of dalteparin sodium as a sterile solution for IV administration. As far as how long the drug effects your blood, I'm unable to provide a direct answer; but listed below is information regarding the half life of this drug (i.e. how long it takes for half of the drug to be excreted from your system): "The half-life of Dalteparin after I.V. inj. is 2 hours and after S.C. inj., 3 to 4 hours. After 4 hours about 20% is seen in the urine, with the major organs for the remainder being the liver, GI tract and kidney. After 72 hours, 70% of a radioactive dalteparin dose has been excreted. ...