Desirudin

Desirudin is recombinant desulfatohirudin, essentially the leech protein made in yeast. It forms a slowly reversible one-to-one complex with thrombin, blocking fibrinogen cleavage, factor V/VIII/XIII activation and thrombin-driven platelet aggregation. Because it needs no cofactor it works where antithrombin is depleted, and it inhibits thrombin already bound inside a clot, which heparin does not. Clearance is almost entirely renal, so kidney function dominates its pharmacokinetics.

Targets: Thrombin (factor IIa)

• · 15 mg twice daily for 9-12 days. Reduced to 5 mg every 12 hours for creatinine clearance 31-60 mL/min and 1.7 mg every 12 hours below 31 mL/min, with aPTT and creatinine checked daily in those groups.

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• commonBleeding and wound haematoma— The dominant risk, as with any parenteral anticoagulant.
• commonInjection-site reaction
• uncommonElevated liver enzymes
• uncommonAnti-hirudin antibody formation— Can prolong the drug's effect rather than neutralise it.
• rareSpinal or epidural haematoma with neuraxial anaesthesia— Boxed warning. Can cause permanent paralysis.
• rareAnaphylaxis— Reported more often on re-exposure to hirudins.

• Active bleeding or irreversible coagulation disorder - there is no antidote for desirudin.
• Known hypersensitivity to hirudins or to natural or recombinant hirudin.
• Indwelling epidural catheter or planned neuraxial anaesthesia, because of the boxed spinal haematoma warning.
• Severe renal impairment without the reduced dose and daily aPTT monitoring.

• conflictheparin — Do not combine; both are direct anticoagulants and the bleeding risk compounds.
• cautionwarfarin — Overlap increases bleeding risk and desirudin itself distorts the INR.
• cautionaspirin — Antiplatelet drugs add to bleeding risk; use only when the indication is strong.

• · Daily aPTT in anyone with renal impairment; hold the dose if it exceeds twice control.
• · Serum creatinine and creatinine clearance before and during therapy.
• · Haemoglobin and platelet count.
• · Neurological checks for leg weakness or numbness if any neuraxial procedure was performed.

Approved prescription anticoagulant in the US and EU but commercially discontinued in the US; availability is limited or absent in most markets.

• Iprivask (desirudin) FDA prescribing information (label)
• Eriksson et al. 1997, desirudin versus enoxaparin for thromboprophylaxis in hip replacement (trial)

Hirudin is the archetype bivalent thrombin inhibitor and desirudin is recombinant hirudin variant-1 without the tyrosine sulfation. The N-terminal domain, held rigid by three disulfides, inserts into and blocks the thrombin catalytic cleft while the long acidic C-terminal tail wraps around exosite 1. The difference from bivalirudin, and it is the clinically important difference, is that this binding is essentially irreversible on any relevant timescale: thrombin does not cleave hirudin the way it cleaves bivalirudin's Arg3-Pro4 bond. So the duration of effect is set entirely by renal clearance rather than by the drug destroying itself. That makes desirudin predictable enough for fixed twice-daily subcutaneous prophylaxis, and it makes renal impairment genuinely dangerous rather than merely inconvenient. Because the effect is on thrombin itself rather than on factor Xa, it suppresses both fibrin formation and thrombin-mediated platelet activation, and it works on clot-bound thrombin, neither of which low-molecular-weight heparin does well.

Renal failure is the whole risk profile. There is no reversal agent, the binding to thrombin does not decay on its own, and a patient whose creatinine climbs on post-operative day two is accumulating an anticoagulant nobody can switch off. The other thing that goes wrong is availability: US commercial supply was discontinued, so a protocol written around desirudin will not survive contact with a real pharmacy. Anti-hirudin antibodies also develop with hirudin exposure and can prolong the effect, which is a second reason repeat courses are not benign.

• Thrombin catalytic site

  Near-irreversible occlusion of the active site; no cofactor required and no neutralisation by platelet factor 4.

• Thrombin exosite 1

  The C-terminal acidic tail binds the fibrinogen-recognition exosite, giving the extremely tight bivalent complex characteristic of the hirudins.

• Eriksson 1997 desirudin versus enoxaparin in total hip replacement Phase 3 · n=2079 · 1.7 weeks · 1997

  Venographically confirmed deep vein thrombosis at the end of 8 to 12 days of prophylaxis. Desirudin 15 mg twice daily reduced proximal DVT from 7.5 to 4.5 percent and total DVT from 25.5 to 18.4 percent versus enoxaparin 40 mg daily, with comparable bleeding.

Anticoagulant effect appears within an hour or two of a subcutaneous dose and steady state is reached inside the first day of twice-daily dosing. Effect washes out over roughly 8 to 12 hours in normal renal function, and far longer as clearance falls.

Nothing sensible stacks with desirudin. It was used as single-agent post-operative prophylaxis, and adding aspirin, an NSAID, another anticoagulant or a neuraxial catheter to it is how the bleeding complications happened. Neuraxial anaesthesia deserves specific mention: an indwelling epidural catheter plus a twice-daily irreversible thrombin inhibitor with renal clearance is the classic setup for spinal haematoma.

Against enoxaparin it wins on venographic DVT, which is why it was approved, but venographic DVT is a surrogate and the trial was not powered for symptomatic events. Against bivalirudin, desirudin is the subcutaneous, irreversible, longer-acting member of the family: better for scheduled prophylaxis, much worse if anything goes wrong. Against modern practice, direct oral anticoagulants have taken the entire indication, which is the honest reason nobody is fighting to bring desirudin back.

No meaningful current price: US supply was discontinued and it was never a chronic-use drug. Historic use was 8 to 12 days of inpatient prophylaxis.

• ?Volume of distribution, protein binding and a published tmax for the subcutaneous route were not resolved in this session and are left null.
• ?I confirmed the hirudin variant-1 sequence from UniProt P01050 and that desirudin is desulfatohirudin, but I did not independently confirm from the Iprivask label that desirudin is residue-for-residue identical to variant-1 rather than carrying additional N-terminal substitutions.
• ?The frequency and clinical impact of anti-hirudin antibodies with desirudin specifically, as opposed to lepirudin, is not something I verified.

• A comparison of recombinant hirudin with a low-molecular-weight heparin to prevent thromboembolic complications after total hip replacement Eriksson BI, Wille-Jorgensen P, Kalebo P, et al., N Engl J Med, 1997 · PMID 9358126

  The registration trial and still the only large randomised comparison showing a direct thrombin inhibitor beating enoxaparin on venographic DVT.

• Desirudin: a review of the pharmacology and clinical application for the prevention of deep vein thrombosis Graetz TJ, Avidan MS, et al., Expert Rev Cardiovasc Ther, 2011 · PMID 21932952

  The most useful single-source pharmacology review of the compound.

• Desirudin dosing and monitoring in moderate renal impairment Nafziger AN, Bertino JS Jr, J Clin Pharmacol, 2010 · PMID 19915180

  Source of the steady-state concentration numbers and of the argument that aPTT monitoring is unnecessary down to CrCl 31 mL/min.

• Hirudin variant-1 (UniProt P01050) UniProtKB

  Source of the 65-residue hirudin variant-1 sequence given above.