Desirudin

In plain language

Desirudin is a discontinued anticoagulant injection, sold as Iprivask, that was used to prevent blood clots in the legs after hip replacement surgery. It is a lab-made copy of hirudin, the anticlotting protein in leech saliva.

Doctors have used medicinal leeches for centuries, and desirudin is the purified active ingredient, rebuilt by bacteria. In trials it beat both heparin and enoxaparin at preventing clots after hip surgery, but its short track record, bleeding risk with no reversal agent, and the arrival of newer anticoagulants ended its run; no desirudin product is currently marketed in the U.S. or Europe.

For students

Desirudin is recombinant hirudin variant 1 (63 residues, about 6,963 Da) expressed in yeast, with the natural C-terminal sulfate missing (desulfatirudin). It binds thrombin with essentially 1:1 stoichiometry at both the catalytic site and exosite I, a bivalent interaction that gives it a nearly irreversible off-rate, in contrast to heparin's antithrombin-mediated catalytic inhibition.

Approved in the U.S. in 2003 for deep vein thrombosis prevention after elective hip replacement, pivotal trials (Eriksson 1997 NEJM) showed significantly fewer DVTs versus enoxaparin (4.5% versus 7.7% in the combined proximal DVT endpoint) with comparable major bleeding. Practical drawbacks (no reversal agent, renal clearance requiring dose reduction, antihirudin antibodies in a minority of patients) plus commercial factors led to discontinuation; no desirudin products are marketed in the U.S. or EU as of the mid-2020s, though leech therapy itself remains an FDA-cleared device use in reconstructive surgery.

For researchers and instructors

Biochemistry. Bivalent thrombin inhibition (active site plus exosite I) is the structural lesson; the molecule inspired the bivalirudin design, which added a cleavable linker to restore reversibility.

Pharmacology. Half-life about 2 hours, renally cleared, monitored by aPTT or ecarin clotting time; contraindicated with active bleeding; antihirudin antibodies can appear with repeat exposure.

Human evidence. Double-blind randomized trials in hip replacement showed superior DVT prevention versus both unfractionated heparin and enoxaparin, establishing efficacy that the market nonetheless did not sustain.

Teaching point. Efficacy alone does not sustain a product: irreversibility, monitoring burden and lack of reversal drove displacement by newer anticoagulants.