Absorption, Distribution and Excretion
Lepirudin administered as a single intravenous bolus injection of 0.4 mg/kg in 9 healthy volunteers (male and female) resulted in a Cmax of 2924 ng/mL, a tmax of 0.17 h and an AUC0-∞ of 2500 ng•h/mL. When 0.1, 0.15 and 0.2 mg/kg of lepirudin was administered as a single intravenous infusion over 6 hours in healthy male volunteers, lepirudin had a corresponding Cmax of 111, 203, and 2446 ng/mL and a corresponding AUC of 612, 1184, and 1446 ng•h/mL. Bioavailability is 100% following injection. Also, it has been reported that following subcutaneous (sc) administration, the bioavailability of lepirudin is almost 100%.
Lepirudin is mostly excreted through urine (48.3%). About 35% of lepirudin is excreted unchanged, while metabolites are found in a smaller proportion (2.5% of M1, 5.4% of M2, 3.9% of M3 and 1.6% of M4).
The volume of distribution of lepirudin at steady state was 12.2 L in healthy young subjects (n=18, 18-60 years), 18.7 L in healthy elderly subjects (n=10, 65-80 years), 18.0 L in renally impaired subjects (n=16, creatinine clearance < 80 mL/min, and 32.1 L in heparin-induced thrombocytopenia patients (n=73). The distribution of lepirudin is mainly restricted to extracellular fluids.
The clearance of lepirudin is proportional to the glomerular filtration rate. On average, lepirudin clearance was 164 mL/min in healthy young subjects (n=18, 18-60 years) and 25% lower in women than in men. In healthy elderly subjects (n=10, 65-80 years), clearance was 139 mL/min, about 20% lower than in younger patients. This is possibly due to the lower creatinine clearance in elderly patients. In renally impaired subjects (n=16, creatinine clearance < 80 mL/min), clearance was 61 mL/min, and in heparin-induced thrombocytopenia patients (n=73), it was 114 mL/min.

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Metabolism / Metabolites
As a polypeptide, lepirudin is expected to be metabolized by the sequential cleavage of amino acids by kidney exoproteases, which have carboxypeptidase and dipeptidase-like activity. The C-terminal cleavage of lepirudin aminoacids (aminoacids 1 to 65) produces four metabolites with anti-thrombotic activity: M1 (aminoacids 1 to 64), M2 (aminoacids 1 to 63), M3 (aminoacids 1 to 62), and M4 (aminoacids 1 to 61).

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Biological Half-Life
Lepirudin has an initial half-life of approximately 10 minutes, and in young healthy volunteers, it has a terminal half-time of 1.3 hours. Lepirudin has a first-order elimination kinetic; plasma concentration increases proportionally as the lepirudin intravenous dose is increased. Elimination half-life values of up to 2 days were detected in patients with marked renal insufficiency (creatinine clearance < 15 mL/min).

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Lepirudin is no longer marketed in the United States. Limited information indicates that lepirudin in doses up to 100 mg daily produce very low levels in milk. Because of its large molecular weight, it would not be expected to be absorbed from breastmilk by the infant. Lepirudin would not be expected to cause any adverse effects in breastfed infants, especially if the infant is older than 2 months.
◉ Effects in Breastfed Infants
One infant was breastfed for 3 months during therapeutic lepirudin use beginning at 7 weeks of age. No bleeding events occurred.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
In human plasma, the protein binding of lepirudin was approximately 3%.

Lepirudin is a heterodetic cyclic peptide composed of 65 amino acids joined in sequence and cyclised by three disulfide bridges between cysteine residues 6-14, 16-28 and 22-39. It is a highly specific inhibitor of thrombin and used as an anticoagulant in patients with heparin-induced thrombocytopenia. It has a role as an EC 3.4.21.5 (thrombin) inhibitor and an anticoagulant. It is a polypeptide, a heterodetic cyclic peptide and an organic disulfide.
Lepirudin is a recombinant hirudin formed by 65 amino acids that acts as a highly specific and direct thrombin inhibitor. Natural hirudin is an endogenous anticoagulant found in Hirudo medicinalis leeches. Lepirudin is produced in yeast cells and is identical to natural hirudin except for the absence of sulfate on the tyrosine residue at position 63 and the substitution of leucine for isoleucine at position 1 (N-terminal end). Lepirudin is used as an anticoagulant in patients with heparin-induced thrombocytopenia (HIT), an immune reaction associated with a high risk of thromboembolic complications. HIT is caused by the expression of immunoglobulin G (IgG) antibodies that bind to the complex formed by heparin and platelet factor 4. This activates endothelial cells and platelets and enhances the formation of thrombi. Bayer ceased the production of lepirudin (Refludan) effective May 31, 2012.
Lepirudin is a yeast cell-derived recombinant polypeptide related to the naturally occurring, leech-derived anticoagulant hirudin. Lepirudin directly binds to and inactivates thrombin, producing dose-dependent increases in the activated partial thromboplastin time (aPTT) and prothrombin time (PT). The mechanism of action of this agent is independent of antithrombin III and is not inhibited by platelet factor 4. Natural hirudin, a family of highly homologous isopolypeptides, is produced in trace amounts by the leech Hirudo medicinalis.

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Drug Indication
Lepirudin is indicated for anticoagulation in adult patients with acute coronary syndromes (ACS) such as unstable angina and acute myocardial infarction without ST elevation. In patients with ACS, lepirudin is intended for use with [aspirin]. Lepirudin is also indicated for anticoagulation in patients with heparin-induced thrombocytopenia (HIT) and associated thromboembolic disease in order to prevent further thromboembolic complications.
Anticoagulation in adult patients with heparin-induced thrombocytopenia type II and thromboembolic disease mandating parenteral antithrombotic therapy. The diagnosis should be confirmed by the heparin-induced platelet activation assay or an equivalent test.

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Mechanism of Action
Lepirudin is a direct thrombin inhibitor used as an anticoagulant in patients for whom heparin is contraindicated. Thrombin is a serine protease that participates in the blood-clotting cascade, and it is formed by the cleavage of pro-thrombin. Active thrombin cleaves fibrinogen and generates fibrin monomers that polymerize to form fibrin clots. Lepirudin binds to the catalytic and substrate-binding sites of thrombin, forming a stable, irreversible and non-covalent complex. This blocks the protease activity of thrombin and inhibits the coagulation process. Each molecule of lepirudin binds to a single molecule of thrombin, and unlike [heparin], it is able to inhibit thrombin in both its clot-bound or free states.

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Pharmacodynamics
Lepirudin is a recombinant hirudin that acts as a highly specific thrombin inhibitor. Its activity is measured by anti-thrombin units (ATUs) that correspond to the amount of lepirudin required to neutralize a unit of the World Health Organization α-thrombin (89/588) standard. The activity of lepirudin is 16,000 ATU/mg. A single molecule of lepirudin binds to a molecule of thrombin, blocking its thrombogenic activity. This drug increases activated partial thromboplastin time (aPTT) and PT (INR) values in a dose-dependent manner, and its mode of action is independent of antithrombin III. Platelet factor 4 does not inhibit lepirudin. The pharmacodynamic effect of lepirudin was evaluated by measuring an increase in aPTT. No saturable effect was observed at the highest tested dose (0.5 mg/kg, IV bolus). Thrombin time was considered an unsuitable routine test for lepirudin monitoring due to the high values detected (200 seconds) even at low doses. The concomitant use of thrombolytic therapy and lepirudin is not recommended due to the high risk of bleeding that may be life-threatening. In patients with a risk of bleeding, a physician should weigh the risks of lepirudin administration against its benefits. There is also an especially high risk of bleeding in patients who weigh less than 50 kg, and a lower dosage is required. Patients with renal impairment have a higher risk of hemorrhagic adverse events.

C287H440N80O111S6

6979.42396068573

6977.967

138068-37-8

Hirudin;8001-27-2

118856773

Typically exists as solid at room temperature

65 °C

-41.3

100

122

166

484

18600

63

S1C[C@@H](C(N[C@@H](C(C)C)C(N[C@@H]([C@@H](C)O)C(NCC(N[C@@H](CCC(=O)O)C(NCC(N[C@@H]([C@@H](C)O)C(N2CCC[C@H]2C(N[C@@H](CCCCN)C(N2CCC[C@H]2C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(NCC(N[C@@H](CC(=O)O)C(N[C@@H](CC2C=CC=CC=2)C(N[C@@H](CCC(=O)O)C(N[C@@H](CCC(=O)O)C(N[C@@H]([C@@H](C)CC)C(N2CCC[C@H]2C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(=O)O)CCC(N)=O)=O)CC(C)C)=O)CC2C=CC(=CC=2)O)=O)CCC(=O)O)=O)CCC(=O)O)=O)=O)=O)=O)=O)=O)=O)=O)CC(=O)O)=O)CC(N)=O)=O)CC2=CNC=N2)=O)CO)=O)CCC(N)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)NC([C@H](CCC(N)=O)NC([C@H](CC(N)=O)NC([C@H](CCCCN)NC([C@H](CCC(=O)O)NC(CNC([C@H](CC(=O)O)NC([C@H](CO)NC(CNC([C@H](CC(C)C)NC([C@H]([C@@H](C)CC)NC([C@@H]2CSSC[C@@H](C(N[C@@H](CCC(=O)O)C(NCC(N[C@@H](CO)C(N[C@@H](CC(N)=O)C(N[C@@H](C(C)C)C(N[C@H](C(NCC(N[C@H](C(NCC(N[C@@H](CC(N)=O)C(N[C@H](C(N2)=O)CCCCN)=O)=O)=O)CCC(N)=O)=O)=O)CS1)=O)=O)=O)=O)=O)=O)NC([C@H](CC(C)C)NC([C@@H]1CSSC[C@@H](C(N[C@H](C(N[C@H](C(N[C@@H](CO)C(NCC(N[C@@H](CCC(N)=O)C(N[C@@H](CC(N)=O)C(N[C@H](C(N1)=O)CC(C)C)=O)=O)=O)=O)=O)CCC(=O)O)=O)[C@@H](C)O)=O)NC([C@H](CC(=O)O)NC([C@H]([C@@H](C)O)NC([C@H](CC1C=CC(=CC=1)O)NC([C@H]([C@@H](C)O)NC([C@H](CC(C)C)N)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O

FIBJDTSHOUXTKV-BRHMIFOHSA-N

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(2S)-5-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-1-[(2S,3S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[2-[[(2S)-2-[[(2S)-4-amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-5-amino-2-[[(2S)-1-[(2S)-6-amino-2-[[(2S)-1-[(2S,3R)-2-[[2-[[(2S)-2-[[2-[[(2S,3R)-2-[[(2S)-2-[[(1R,6R,9S,12S,15S,18S,24S,27S,33S,36S,39R,44R,47S,53S,56S,59S,67S,73S,76S)-15,76-bis(4-aminobutyl)-44-[[(2S)-2-[[(4R,7S,10S,13S,19S,22S,25S,28R)-28-[[(2S)-2-[[(2S,3R)-2-[[(2S)-2-[[(2S,3R)-2-[[(2S)-2-amino-4-methylpentanoyl]amino]-3-hydroxybutanoyl]amino]-3-(4-hydroxyphenyl)propanoyl]amino]-3-hydroxybutanoyl]amino]-3-carboxypropanoyl]amino]-10-(2-amino-2-oxoethyl)-13-(3-amino-3-oxopropyl)-22-(2-carboxyethyl)-25-[(1R)-1-hydroxyethyl]-19-(hydroxymethyl)-7-(2-methylpropyl)-6,9,12,15,18,21,24,27-octaoxo-1,2-dithia-5,8,11,14,17,20,23,26-octazacyclononacosane-4-carbonyl]amino]-4-methylpentanoyl]amino]-12,56,73-tris(2-amino-2-oxoethyl)-9,67-bis(3-amino-3-oxopropyl)-36-[(2S)-butan-2-yl]-18,47-bis(2-carboxyethyl)-24-(carboxymethyl)-27,53-bis(hydroxymethyl)-33-(2-methylpropyl)-8,11,14,17,20,23,26,29,32,35,38,45,48,51,54,57,60,62,65,68,71,74,77-tricosaoxo-59-propan-2-yl-3,4,41,42-tetrathia-7,10,13,16,19,22,25,28,31,34,37,46,49,52,55,58,61,63,66,69,72,75,78-tricosazabicyclo[37.22.17]octaheptacontane-6-carbonyl]amino]-3-methylbutanoyl]amino]-3-hydroxybutanoyl]amino]acetyl]amino]-4-carboxybutanoyl]amino]acetyl]amino]-3-hydroxybutanoyl]pyrrolidine-2-carbonyl]amino]hexanoyl]pyrrolidine-2-carbonyl]amino]-5-oxopentanoyl]amino]-3-hydroxypropanoyl]amino]-3-(1H-imidazol-4-yl)propanoyl]amino]-4-oxobutanoyl]amino]-3-carboxypropanoyl]amino]acetyl]amino]-3-carboxypropanoyl]amino]-3-phenylpropanoyl]amino]-4-carboxybutanoyl]amino]-4-carboxybutanoyl]amino]-3-methylpentanoyl]pyrrolidine-2-carbonyl]amino]-4-carboxybutanoyl]amino]-4-carboxybutanoyl]amino]-3-(4-hydroxyphenyl)propanoyl]amino]-4-methylpentanoyl]amino]-5-oxopentanoic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)