Lepirudin

Lepirudin was a recombinant hirudin (desulfated on Tyr-63, plus Leu1-Thr2 substitutions) approved for anticoagulation in HIT with associated thromboembolic disease. It was the first direct thrombin inhibitor approved for HIT. Bayer ceased production in 2012 for commercial reasons; supply was depleted by mid-2013. Bivalirudin and argatroban are the current standard-of-care alternatives.

Lepirudin is a highly specific, irreversible direct thrombin inhibitor that forms a 1:1 stoichiometric complex with thrombin, blocking both the catalytic active site and the substrate-recognition exosite. Unlike heparin, it does not require antithrombin III and is active against clot-bound thrombin. It does not cause HIT (no platelet factor 4 interaction).

Pharmacokinetics: IV administration; half-life ~1.3 h (prolonged to >50 h in renal failure); primarily renal excretion (>90% unchanged); dose adjustment mandatory in renal impairment.

Approved labeled regimen (historical)

The label summary below is product-, indication-, and jurisdiction-specific; consult the full current label and a licensed clinician/pharmacist.

This documents the historical US Refludan regimen; the product is no longer marketed. Never extrapolate this information to "research" material labeled as hirudin.

Adults: IV bolus 0.4 mg/kg (max 44 mg) over 15-20 sec, followed by IV infusion 0.15 mg/kg/h (max 16.5 mg/h). Adjusted to maintain aPTT ratio 1.5-2.5x baseline. Renal impairment: dose adjustment required. Duration: 2-10 days depending on clinical need.

Studied regimens (not recommendations)

Lower starting doses (0.1-0.2 mg/kg/h) studied in renal impairment. Variable dosing across centers based on aPTT monitoring.

What is not established

• Optimal target aPTT range not validated in an RCT.

• Pediatric population: only case reports (two pediatric patients in HAT-2).

• No comparative trial against argatroban or danaparoid (the other HIT treatments at the time).

Established label risks (historical)

• Bleeding (most common/important): major bleeding 13-21% across studies; intracranial, retroperitoneal, and gastrointestinal reported.

• Anaphylaxis (especially with re-exposure within 3 months): antihirudin antibodies can cause severe allergic reactions.

• Anti-hirudin antibodies: developed in ~40-70% of patients; generally not associated with loss of efficacy but may increase anticoagulant effect (due to delayed renal clearance of antibody-bound drug), requiring close aPTT monitoring.

• Contraindicated in hypersensitivity to hirudins and active bleeding/irreversible coagulation disorders.

Human-study signals

• No RCT-level data; evidence relied on comparison to historical cohorts.

Unknowns and product-quality risks

• Marketing withdrawal means the product is not available. There is no approved "lepirudin" on the market. Any material sold as "lepirudin" or "Refludan" is either counterfeit, expired, or unapproved.

Synergistic bleeding risk with antiplatelet agents and other anticoagulants. No CYP interactions. Exclusively renally eliminated; severe renal impairment (CrCl <15 mL/min or dialysis) requires extreme dose reduction or contraindication.

WADA status: lepirudin was not identified by exact name in the 2026 Prohibited List. Its discontinued/withdrawn status is not "moot": S0 turns on whether the substance has a current governmental approval for human therapeutic use, which this page has not established in any jurisdiction. Athletes need a current, case-specific classification, and grey-market hirudin cannot be assumed equivalent to historical REFLUDAN.

• No RCT ever conducted in HIT (the indication was approved based on historically controlled studies, which would not meet modern regulatory standards).

• Optimal aPTT target (1.5-2.5 or other) was established empirically.

• Long-term safety beyond acute treatment period is not documented (by design — only acute use was intended).

• Databases and registries: FDA label (accessdata.fda.gov), DailyMed, EMA (withdrawn), PubMed, ClinicalTrials.gov

• Search terms: lepirudin, Refludan, HIT, heparin-induced thrombocytopenia, hirudin, marketed withdrawal

• Last searched: 2026-08-06

• Inclusion emphasis: FDA/EMA labels (historical), pivotal studies, regulatory withdrawal documentation

1. FDA prescribing information: REFLUDAN (lepirudin rDNA) for injection. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2006/020807s011lbl.pdf (accessed 2026-08-06). Product discontinued — label provided for historical reference only.

2. Greinacher A, et al. Recombinant hirudin (lepirudin) provides safe and effective anticoagulation in patients with heparin-induced thrombocytopenia: a prospective study. Circulation. 1999;99(1):73-80. DOI: 10.1161/01.CIR.99.1.73.

3. Greinacher A, et al. Lepirudin for the treatment of heparin-induced thrombocytopenia — final results of the HAT-2 study. Blood. 2001;98(11):274a.

4. EMA: Refludan — withdrawal of marketing authorisation. Available at: https://www.ema.europa.eu/en/medicines/human/EPAR/refludan (accessed 2026-08-06).

5. BfArM: Dear Doctor Letter — permanent discontinuation of Refludan. Available at: https://www.bfarm.de/SharedDocs/Risikoinformationen/Pharmakovigilanz/EN/RHB/2011/rhb-refludan.html (accessed 2026-08-06).

6. World Anti-Doping Agency. 2026 Prohibited List. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf

7. PubChem. Lepirudin, CID 118856773. https://pubchem.ncbi.nlm.nih.gov/compound/118856773 (accessed 2026-08-06).