Low Molecular Weight Heparin Overdose: A 10 Year Case Series

Abstract

Background: Low molecular weight heparin (LMWH) is used for the treatment and prevention of coagulative disorders. Few patients receiving therapeutic doses of LMWH develop major hemorrhage. Currently there are few reports in the literature on acute overdose on adults. In this study, clinical profile, treatment and outcome of 21 patients who acutely overdosed enoxaparin are described. Methods: A retrospective chart review of California Poison Control System (CPCS) database: Visual Dot Lab during 1997 to 2007 was obtained. All patients with a definite reported overdose of subcutaneous injection of LMWH were included. Results: In total, 21 patients who were all exposed to enoxaparin were studied. The reasons for overdose included medical miscalculation (3 cases, all infants), intentional misuse (2 patients), accidental overdose (7 cases), suicidal attempt (7 cases) and unknown in 2 patients. 7 cases were documented to have overdosed more than 2 times the therapeutic dose. The overdose ranged from 50 mg to 1300mg (0.1-80 times the therapeutic range). No patients were documented to experience bleeding or have thrombocytopenia although complete follow-up was only available for 11 patients. Reassurance was given to patients with less than 0.14 times the therapeutic dose. The 2 patients who received protamine were overdosed with more than 2.5 times the therapeutic dose of enoxaparin. Conclusion: Most patients had no complications and were not treated with protamine. This study suggests that a large dosage of LMWH is unlikely to result in any life threatening complications, though further studies are needed to certainly conclude about this. The use of protamine in LMWH overdose seems to remain controversial.