Particular care should be taken to avoid overdosage with protamine sulfate. Neutralization of enoxaparin by protamine Time Since LOVENOX DoseĪ second infusion of 0.5 mg protamine per 1 mg LOVENOX may be administered if the aPTT measured 2 to 4 hours after the first infusion remains prolonged. Attending physicians confronted with a potential overdosage of enoxaparin should always use their best clinical judgment in determining the appropriate dosing regimen of protamine to be administered. In the event that prompt reversal of the anticoagulant effects of enoxaparin is required at any time after LOVENOX dosing, the following table is provided as a guide for initial use of protamine. Anti-factor Xa activity is never completely neutralized (maximum about 60%). However, even with higher doses of protamine, the aPTT may remain prolonged to a greater extent than usually seen with unfractionated heparin. This effect may be largely neutralized by slow intravenous injection of protamine sulfate. The anticoagulant effect of LOVENOX is inhibited by protamine. In more serious cases, protamine should be administered. LOVENOX should be immediately discontinued, at least temporarily, in cases of significant excess dosage. The anti-factor Xa level at 24 hours was 1.39 IU/mL.Accidental overdosage following administration of LOVENOX (enoxaparin) may lead to hemorrhagic complications. Subsequent testing for anti-factor Xa revealed an initial level of 4.72 IU/mL upon admit (therapeutic range 0.50 – 1.10 IU/mL), decreasing to 4.52 and 3.82 IU/mL after the infusions of protamine sulfate. The patient did not exhibit any signs of bleeding during treatment, and tolerated the infusions of protamine sulfate without any adverse effects.

Rebound phenomenon was noted 3–8.5 hours later as the aPTT increased (70 to 89 seconds), however, no additional protamine sulfate was given. A second infusion of protamine sulfate was administered 2 hours later, and the aPTT decreased further to 49 seconds.

An initial dose of protamine sulfate, 250 mg mixed in 500 ml of 0.9% sodium chloride, was infused over 3–4 hours. Anti- factor Xa levels were not available at the time of treatment. Initial laboratory assessment, approximately 2 hours post-suicide attempt, revealed an elevated aPTT of >150 seconds (reference range 23–38 seconds). The remainder of his physical exam was unremarkable, and he exhibited no overt signs of bleeding. He was somnolent but arousable with bruising noted around multiple injection sites on his abdomen. Upon admission, he reported self-administration of 20 subcutaneous injections of 100 mg of enoxaparin (2000 mg) and 8 tablets of quetiapine (400 mg/tablet) in an attempt to commit suicide. We report a challenging case of a large overdose of LMWH, successfully treated despite the lack of appropriate laboratory monitoring tests.Ī 50-year old Caucasian man with a past medical history significant for bipolar disorder, schizophrenia, hypertension, and pulmonary embolism secondary to a hypercoagulable state caused by tetrahydrofolate reductase deficiency was found unresponsive and transported to the emergency department. Anti-factor Xa levels, however, are not readily available at most institutions. Peak plasma levels of LMWH are found 3–4 hours after administration, and the half-life of the drug is 4.5–7 hours. Plasma levels of LMWH can be monitored by measuring anti-factor Xa levels however, studies correlating large overdoses have not been performed. Both cases were treated with an approximate 1 to 1 ratio of protamine sulfate to LMWH (30 mg and 20 mg, respectively) and showed incomplete reversal of anticoagulation. Two reports of enoxaparin overdose have been described in the literature a neonate received a 10-fold overdose and a 64-year old man received an extra daily dose. Due to its safety profile, there has been little literature regarding management and treatment of overdoses. Enoxaparin, a low molecular weight heparin (LMWH), is used for prophylaxis and treatment of venous and arterial thromboembolism.

Antidote for lovenox