Refludan

Generic name: lepirudin
Dosage form: injection
Drug class:Thrombin inhibitors

Medically reviewed by Drugs.com. Last updated on Feb 21, 2022.

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Refludan Description

Refludan [lepirudin (rDNA) for injection] is a highly specific direct inhibitor of thrombin. Lepirudin, (chemical designation: [Leu1, Thr2]-63-desulfohirudin) is a recombinant hirudin derived from yeast cells. The polypeptide composed of 65 amino acids has a molecular weight of 6979.5 daltons. Natural hirudin is produced in trace amounts as a family of highly homologous isopolypeptides by the leech Hirudo medicinalis. The biosynthetic molecule (lepirudin) is identical to natural hirudin except for substitution of leucine for isoleucine at the N-terminal end of the molecule and the absence of a sulfate group on the tyrosine at position 63.

The activity of lepirudin is measured in a chromogenic assay. One antithrombin unit (ATU) is the amount of lepirudin that neutralizes one unit of World Health Organization preparation 89/588 of thrombin. The specific activity of lepirudin is approximately 16,000 ATU/mg. Its mode of action is independent of antithrombin III. Platelet factor 4 does not inhibit lepirudin. One molecule of lepirudin binds to one molecule of thrombin and thereby blocks the thrombogenic activity of thrombin. As a result, all thrombin-dependent coagulation assays are affected, eg, activated partial thromboplastin time (aPTT) and prothrombin time (PT /INR) values increase in a dose-dependent fashion (Roethig 1991).

Refludan is supplied as a sterile, white, freeze-dried powder for injection or infusion and is freely soluble in Sterile Water for Injection USP or 0.9% Sodium Chloride Injection USP.

Each vial of Refludan contains 50 mg lepirudin. Other ingredients are 40 mg mannitol and sodium hydroxide for adjustment of pH to approximately 7.

Refludan - Clinical Pharmacology

Pharmacokinetic Properties

The pharmacokinetic properties of lepirudin following intravenous administration are well described by a two-compartment model. Distribution is essentially c...