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PeptideAI
Approved drugcardiovascular

Lepirudin

A recombinant hirudin drip that was the reference treatment for heparin-induced thrombocytopenia before it was withdrawn from the market.

Also known as Refludan, recombinant hirudin, r-hirudin, Refludan, HBW 023

Approved drug — Licensed by a major regulator for human use, with phase-3 trial data behind it.

Was FDA- and EMA-approved on the HAT-1 through HAT-3 prospective studies, which used historical controls rather than randomisation. Manufacture was discontinued in 2012 and argatroban and bivalirudin took over the indication, so lepirudin is now historically important rather than clinically available.

How it works

Lepirudin is yeast-derived recombinant hirudin differing from the natural leech protein by a leucine at position 1 and the absence of a sulfate group on Tyr63. It binds thrombin bivalently, occupying the catalytic cleft and exosite I with a picomolar dissociation constant, which makes the inhibition functionally irreversible over clinical timescales. Because it works independent of antithrombin and does not interact with platelet factor 4, it is safe in heparin-induced thrombocytopenia. Elimination is renal, so dosing collapses in kidney failure and the drug accumulates dangerously.

Targets: Thrombin (factor IIa)

Dosing

ProtocolDoseFrequencyRoute
Heparin-induced thrombocytopenia with thrombosis (historical label protocol)Started as soon as HIT is suspected and heparin is stopped.—bolus then continuous infusionintravenous
  • · 0.4 mg/kg IV bolus (max 44 mg) followed by 0.15 mg/kg/hour (max 16.5 mg/hour), then titrated to an aPTT ratio of 1.5-2.5. Weight-based, so no fixed microgram dose applies. Doses were cut sharply or the bolus omitted entirely in renal impairment.

Titration

Titrated strictly to aPTT ratio 1.5-2.5, rechecked 4 hours after every rate change. In renal impairment the infusion is reduced to as little as 15 percent of the standard rate or given as intermittent boluses.

Cycling

Used for the acute thrombotic phase of HIT, typically 2 to 10 days, then bridged to an oral anticoagulant once the platelet count recovers.

Work out your exact syringe units →

Pharmacology

Half-life
About 1.3 hours intravenously in normal renal function; up to 2 days or longer in severe renal failure.
Onset
Immediate on IV bolus; aPTT is checked 4 hours after starting the infusion.
Routes
intravenous, subcutaneous
Molecule
Recombinant 65-amino-acid hirudin variant
Sequence length
65 amino acids
Molecular weight
6979.5 Da

Handling

Diluent
Sterile water for injection or 0.9% saline, then diluted for infusion
Typical mix
1 mL
Vial sizes
50 mg
Lyophilised
Was stored at 2-25 C.
Reconstituted
Was used immediately; solutions were held no more than 24 hours at room temperature.

Mixing

Historical hospital preparation: 50 mg vial reconstituted with 1 mL, then diluted to 5 mg/mL or 2 mg/mL for infusion.

Side effects

  • very commonBleeding, including fatal haemorrhage— Major bleeding occurred in a substantial minority of treated patients; there is no antidote.
  • commonAnti-hirudin antibodies— Formed in roughly 40-70 percent of treated patients and paradoxically increased drug exposure by slowing renal clearance.
  • commonFever
  • commonAbnormal liver function tests
  • rareAnaphylaxis on re-exposure— Fatal anaphylaxis was reported, particularly with a second treatment course, and contributed to the drug's withdrawal.

Do not use if

  • Active bleeding or high bleeding risk, since no reversal agent exists.
  • Prior exposure to lepirudin or any hirudin, because of the fatal anaphylaxis risk on re-exposure.
  • Severe renal impairment unless dosing is drastically reduced with aPTT guidance.
  • Pregnancy, where safety was never established.

Combining it

  • cautionwarfarin — Lepirudin markedly raises the INR, so overlap must be managed carefully and the platelet count should recover before starting warfarin.
  • cautionthrombolytics — Combined use sharply increases intracranial haemorrhage risk.
  • redundantbivalirudin — Both are direct thrombin inhibitors; bivalirudin and argatroban replaced lepirudin clinically.

What to monitor

  • · aPTT ratio 4 hours after starting and 4 hours after each rate change, targeting 1.5-2.5.
  • · Daily platelet count to confirm recovery from HIT.
  • · Serum creatinine, since renal function dictates dosing.
  • · Haemoglobin and clinical bleeding assessment.

Legal status

Formerly an approved prescription anticoagulant; withdrawn from the market worldwide in 2012 and no longer manufactured.

References

  • Refludan (lepirudin) prescribing information, withdrawn 2012 (label)
  • Greinacher et al. 1999, HAT-1 and HAT-2 lepirudin studies in heparin-induced thrombocytopenia (trial)

Mechanism in depth

Mechanistically lepirudin is desirudin's twin: a bivalent, effectively irreversible thrombin inhibitor that blocks both the catalytic site and exosite 1, works on clot-bound thrombin, needs no antithrombin cofactor and is not neutralised by platelet factor 4. The reason it mattered clinically is specific to heparin-induced thrombocytopenia. In HIT, antibodies against the heparin-PF4 complex cross-link platelet FcgammaRIIa receptors, causing massive platelet activation and a thrombin burst; the patient is thrombocytopenic and simultaneously prothrombotic. Stopping heparin alone does not stop that thrombin generation, which is why HIT patients throw clots after heparin withdrawal. A direct thrombin inhibitor with no structural relationship to heparin interrupts the thrombin burst without feeding the antibody. Lepirudin proved that principle: across HAT-1 to HAT-3, new thromboembolic complications after starting treatment fell to 11.9 percent versus 32.1 percent in a historical control group. The cost was major bleeding in 17.6 percent, against 9.1 percent in controls, and that ratio is the reason argatroban and bivalirudin displaced it.

What usually goes wrong

Bleeding, and it is not rare: roughly one in six patients across the prospective programme had a major bleed. Renal impairment turns a 1.3-hour drug into a multi-day one. Anti-hirudin antibodies accumulate with exposure and can both raise drug levels and, on re-exposure, cause anaphylaxis, which was the trigger for regulatory warnings. And the drug no longer exists commercially: manufacture stopped in 2012. Anyone reading about lepirudin should be reading it as history that explains argatroban and bivalirudin practice, not as an option.

Bloodwork worth running

MarkerWhenWhy it matters
aPTT ratioFour hours after starting or after any rate change, then at least daily once stable.The dosing target for the entire HAT programme. Lepirudin has no therapeutic drug level assay in routine use, so aPTT is the only feedback loop.Act if: Target aPTT ratio 1.5 to 2.5. Above 2.5, stop the infusion for two hours and restart at half the rate.
Platelet countDaily.Recovery of the platelet count is the primary sign that HIT is being controlled, and it is the trigger to bridge to warfarin.Act if: Do not start warfarin until platelets are above 150,000 per microlitre; warfarin started during active HIT causes venous limb gangrene.
Creatinine and eGFRDaily.Half-life goes from 1.3 hours to more than a day in severe renal impairment. This is the dominant determinant of bleeding risk.Act if: Any rise in creatinine on a lepirudin infusion should trigger an immediate rate reduction rather than waiting for the aPTT to drift.
HaemoglobinDaily.Major bleeding occurred in about one in six treated patients across the HAT trials.Act if: A 2 g/dL fall or any overt bleed means stop; there is no reversal agent, only time and haemofiltration.
Anti-hirudin antibodiesNot routinely available in real time; the practical surrogate is an unexplained rise in aPTT on an unchanged infusion rate after day 5.Anti-hirudin IgG develops in a substantial fraction of treated patients and can paradoxically increase drug exposure by slowing renal elimination of the antibody-drug complex, so a stable infusion rate can drift into overdose after several days.Act if: Rising aPTT on a fixed rate after the first week means reduce the rate, not increase monitoring frequency alone.

Pharmacokinetics

Bioavailability
100%
Crosses blood-brain barrier
no
Accumulates
Yes — doses stack before steady state
Metabolism
Minimal. Cleared as intact protein and catabolic fragments rather than by defined enzymatic pathways.
Elimination
Renal excretion and tubular catabolism. In anuric patients the drug essentially does not leave.

Receptor targets

  • Thrombin catalytic site

    Essentially irreversible active-site blockade; duration governed only by renal clearance.

  • Thrombin exosite 1

    C-terminal tail binding that gives the hirudins their femtomolar-class bivalent affinity and access to fibrin-bound thrombin.

Trials

  • HAT-1 and HAT-2 Prospective cohort with historical controls · n=198 · 1999

    Combined endpoint of death, limb amputation and new thromboembolic complications in laboratory-confirmed HIT, compared against a historical control group. Lepirudin reduced new thrombosis substantially.

  • HAT-3 and combined HAT analysis Prospective cohort with historical controls · n=403 · 2005

    Across all three prospective studies, the combined endpoint occurred in 20.3 percent after starting lepirudin, with new thromboembolic complications in 7.4 percent versus 32.1 percent in historical controls, and major bleeding in 17.6 percent versus 9.1 percent.

What to expect, and when

Immediate on IV bolus or within the first hour of infusion; aPTT reaches target within 4 hours in most patients. Offset over 4 to 6 hours in normal renal function, far longer otherwise.

Stacking and comparisons

In HIT, the point is that nothing heparin-shaped goes anywhere near the patient, including heparin flushes and heparin-bonded catheters. Warfarin is the specific trap: starting it while the platelet count is still low and thrombin generation is high causes protein C depletion faster than factor II depletion and produces venous limb gangrene. Bridge only after platelet recovery, with the direct thrombin inhibitor overlapping for at least five days. Note also that lepirudin prolongs the INR, so warfarin dosing during overlap cannot be read off the INR naively.

Argatroban replaced it because argatroban is hepatically cleared, which makes it usable in the renal failure that HIT patients frequently have, and because argatroban does not raise anti-drug antibodies. Bivalirudin took the interventional and cardiac surgery share for the same reasons plus its self-limiting kinetics. Against fondaparinux, which is now widely used off-label in HIT, lepirudin has better mechanistic logic but far more bleeding.

Rough cost

Withdrawn from the market in 2012; no current price exists.

Genuinely uncertain

  • I could not confirm the exact [Leu1, Thr2] substitution pattern from a primary source in this session; a patent-derived sequence I retrieved showed Leu1 with Val2, which conflicts with the commonly cited descriptor, so the sequence is marked unverified.
  • The reported incidence of anti-hirudin antibodies, usually quoted around 40 to 60 percent with prolonged exposure, was not verified here.
  • Volume of distribution and protein binding were not resolved.

Papers