Bivalirudin

Bivalirudin is a kind of synthetic novel anticoagulants. It is the direct, specific and reversible inhibitor of thrombin. It was developed by the Swiss Basset (Biogen) originally. Then it was transferred to the United States Medicines Company, and approved for marketing in the United States in 2000. Its anticoagulant ingredient is a kind of 20 peptides derived from hirudin. Bivalirudin can specifically bind with catalytic site and the anion binding site of whether thrombin that is in the blood circulation or thrombus-bound thrombin, thus directly inhibiting thrombin activity. And its role is characterized by short, reversible. Early clinical studies show that the anticoagulation treatment of bivalirudin is good. And the incidence of bleeding events is low. So its use is safer than traditional heparin therapy. It is mainly used for the prevention of angioplasty interventional treatment of ischemic complications of unstable angina pectoris before and after.
Bivalirudin has a inhibitory effect on soluble and thrombus-bound thrombin in vitro. That effect cannot be affected by products that are released by platelet, and it can extend plasma activated partial thromboplastin time, thrombin time and prothrombin time of normal human with a dose-dependent manner. It is suitable for percutaneous coronary intervention (PCI) unstable angina. In 2010, domestic PCI operation cases reached 300,000. The annual compound growth rate was over 30%. This showed that sales prospects of bivalirudin after the listing are considerable.
Clinically experiments prove that bivalirudin is more effective than the current mainstream unfractionated heparin/low molecular weight heparin and platelet glycoprotein receptor antagonist in applications around PCI. Especially the risk of bleeding has a significant reduction, and the use safety of anticoagulants is greatly improved:
1. It can significantly reduce the incidence of bleeding in elective PCI patients. The total clinical outcome risk fell 14%.
2. It does not cause antibody-mediated thrombocytopenia.
3. Reversibly bind with thrombin. Short half-life. Hard to develop ischemic and hemorrhagic complications.
4. It is not mainly excreted through the kidneys and can be safely used in patients with renal impairment.
The above information is edited by the chemicalbook of Duan Yalan.

The first dose 0.75 mg/kg is injected intravenously. Then it is continuously injected intravenously with 1.75 mg/kg per hour by percutaneous coronary intervention. ACT should be monitored after first intravenous injection for 5 minutes. If necessary, 0.3mg/kg bivalirudin is injected again. After percutaneous coronary intervention treatment, it is continued to use for 4h. If necessary, 0.2 mg/kg bivalirudin per hour is continuously injected for 20h. When it is used, using 5mL water for injection to dissolve, and then using 50 mL normal saline to be diluted to 5mg/mL solution.

1. To guard against the occurrence of bleeding, including intracranial hemorrhage, thrombocytopenia. Intravenously injection should stop immediately when a sudden drop in blood pressure and blood volume.
2. Back pain, headaches, insomnia, anxiety, abdominal pain, diarrhea, nausea, vomiting, low blood pressure can be seen. When serious bivalirudin should be discontinued. Patients with renal dysfunction should reduce its dosage.
3. Patients allergic to bivalirudin and active bleeding should be banned. Women, infants, breast-feeding women should be careful to use this product.
4. Bivalirudin cannot bind with plasma proteins and red blood cells. When bivalirudin is used with heparin, warfarin, or thrombolytic drugs, it will increase the possibility of bleeding of patients. Once the excessive use, it should be discontinued. The product can be cleared by hemodialysis.

In order to prove the efficacy and safety of bivalirudin in the treatment of patients with acute coronary syndrome (ACS), the researchers designed the ACUITY clinical research.
ACUITY clinical trial was to compare the efficacy and safety of bivalirudin with traditional heparin platelet glycoprotein Ⅱb/Ⅲa inhibitor therapy in high-risk ACS patients. ACUITY results published in a recent issue of the "New England Journal of Medicine" showed that the efficacy of bivalirudin alone is same with traditional anticoagulant drugs. While preventing ischemic events, it can significantly reduce bleeding.
ACUITY trial chooses 13,819 patients from 17 countries with high-risk non-ST segment elevation acute coronary syndrome. Patients were randomly divided into three group: unfractionated heparin or low molecular weight heparin and glycoprotein Ⅱb/Ⅲa inhibitor combination group, bivalirudin and glycoprotein Ⅱb/Ⅲa inhibitor combination group and bivalirudin alone group. The primary endpoint is ischemic composite endpoint occurred in 30 days (death, myocardial infarction or unplanned revascularization due to ischemia), major bleeding events and overall clinical outcomes (the sum of ischemic or serious bleeding events). The results showed that compared with heparin and glycoprotein Ⅱb/Ⅲa inhibitor combination group, the incidence of ischemic events in bivalirudin alone group did not significantly increase (7.8% vs 7.3%;. P = 0.32 ). Bleeding risk decreased 47% (3.0% vs. 5.7%; P <0.001), and the overall clinical outcomes were also improved significantly (10.1% vs.11.7%; P = 0.015). Using bivalirudin alone is not inferior to the combination of heparin and glycoprotein Ⅲb/Ⅲa inhibito. In addition, the combinations of bivalirudin and glycoprotein Ⅱb/Ⅲa inhibitor are also not inferior to heparin and glycoprotein Ⅱb/Ⅲa inhibitors, but no advantage at all.
Stone, the study leader in Columbia University Medical Center Stone, believes that " for high-risk ACS patients with early intervention therapy, bivalirudin is a suitable alternative to heparin or enoxaparin when used with glycoprotein Ⅱb/Ⅲa inhibitors. Compared with the combinations of heparin and glycoprotein Ⅱb/Ⅲa inhibitors or the combinations of bivalirudin and glycoprotein Ⅱb/Ⅲa inhibitor, bivalirudin treatment can make patients to have a more significant net clinical benefit. And event-free survival in 30 days can be improved. "

Alternative medicine as ordinary heparin and platelet glycoprotein IIb/IIIa antagonists.

Bivalirudin was launched in New Zealand as an anticoagulant for i.v. treatment of patients with unstable angina undergoing percutaneous transluminal coronary angioplasty. Bivalirubin is a synthetic 20 amino acid peptide rationally modeled on hirudin (residues 53- 64), the most potent and specific naturally-occuring known inhibitor of thrombin, the enzyme that plays a key role in hemostasis and blood clot formation. This peptide is a direct thrombin inhibitor that maintains the unique bivalent binding properties of hirudin to the catalytic site and to the fibrin-recognition exosite of the enzyme, so acting directly on thrombin with high affinity and specificity. In vitro studies demonstrated that alpha- and zeta-thrombins, both with the higher fibrinogen-procoagulant activities, were inhibited. In rats receiving high doses of bivalirudin, the platelet deposition in carotide was reduced by 63% compared to controls. The results of clinical studies, conducted only in patients receiving concomitant aspirin, suggested that the use of bivalirudin was more efficacious and more predictable than unfractionated heparin, with fewer bleeding complications. Despite some unresolved developmental issues, the attractive properties of this novel agent could make it a useful alternative to heparin in a variety of coagulation disorders.

Bivalirudin is an inhibitor of α- and ζ-thrombin (K_is = 2.56 and 1.84 nM, respectively), enzymes that exhibit high fibrinogen-clotting activities. It is selective for α- and ζ-thrombin, lacking activity at trypsin and γ-thrombin, which lacks clotting activity, at a >1,000-fold excess of bivalirudin. Bivalirudin inhibits α-thrombin-stimulated activation of the clotting factors Factor X, Factor V, and prothrombin in contact-activated plasma at a concentration of 0.1 μM. Administration of bivalirudin (0.5-1.5 mg/kg, i.v.) reduces platelet deposition in a rat carotid endarterectomy model in a dose-dependent manner. Formulations containing bivalirudin have been used to prevent ischemic events during angioplasty for thrombus-containing lesions.

Biogen (US)

Anticoagulant; antithrombotic.

ChEBI: A synthetic peptide of 20 amino acids, comprising D-Phe, Pro, Arg, Pro, Gly, Gly, Gly, Gly, Asn, Gly, Asp, Phe, Glu, Glu, Ile, Pro, Glu, Glu, Tyr, and Leu in sequence. A congener of hirudin (a naturally occurring drug found in the saliva o the medicinal leech), it a specific and reversible inhibitor of thrombin, and is used as an anticoagulant.

A 20 amino acid polypeptide [1], bivalirudin (hirulog) is a synthetic version of hirudin. Its amino-terminal D-Phe-Pro-Arg-Pro domain, which interacts with the active site of thrombin, is linked via four Gly residues to a dodecapeptide analogue of the carboxy-terminal of hirudin. Like hirudin, bivalirudin also forms a 1:1 stoichiometric complex with thrombin. Once bound, however, the Arg-Pro bond at the amino-terminal of bivalirudin is cleaved by thrombin, thereby restoring active site functions of the enzyme complexes of α-thrombin [2].
Hirulog-8 has the formula: H-(D-Phe)-Pro-Arg-Pro-(Gly)4-Asn-Gly-Asp-Phe- Glu-Glu-Ile-Pro-Glu-Glu-Tyr-Leu-OH. Hirulog-8 was synthesized by conventional solid-phase peptide synthesis employing an Applied Biosystems 430 A Peptide Synthesizer. This peptide was synthesized using BOC-L-Leucine- O-divinylbenzene resin. Additional t-BOC-amino acids (Peninsula Laboratories, Belmont, Calif.) used included BOC-O-2,6-dichlorobenzyl tyrosine, BOC-Lglutamic acid (γ-benzyl ester), BOC-L-proline, BOC-L-isoleucine, BOC-Lphenylalanine, BOC-L-aspartic acid (β-benzyl ester), BOC-glycine, BOC-Lasparagine, BOC-L-phenylalanine, and BOC-L-arginine. In order to achieve higher yields in synthesis, the (Gly)4 linker segment was attached in two cycles of manual addition of BOC-glycylglycine (Beckman Biosciences, Inc., Philadelphia, Pa.). After completion of synthesis, the peptide was fully deprotected and uncoupled from the divinylbenzene resin by treatment with anhydrous HF:p-cresol:ethylmethyl sulfate (10:1:1, v/v/v). Following removal from the resin, the peptide was lyophilized to dryness.
Crude Hirulog-8 was purified by reverse-phase HPLC employing an Applied Biosystems 151A liquid chromatographic system and a Vydac C18 column (2.2x25 cm). The column was equilibrated in 0.1% TFA/water and developed with a linear gradient of increasing acetonitrile concentration from 0 to 80% over 45 minutes in the 0.1% TFA at a flow-rate of 4.0 ml/min. The effluent stream was monitored for absorbance at 229 nm and fractions were collected manually. We purified 25-30 mg of crude Hirulog-8 by HPLC and recovered 15-20 mg of pure peptide.
The structure of purified Hirulog-8 was confirmed by amino acid and sequence analyses.

Angiomax (Medicinova).

Anticoagulant

Bivalirudin is a specific and reversible bivalent direct thrombin inhibitor. Bivalirudin specifically binds to both the catalytic site and to the anion-binding exosite of circulating and clot-bound thrombin.

Bivalirudin is a rapid-onset, short-acting DTI that binds to both the active site and the exosite-1 of thrombin. Unlike lepirudin, bivalirudin is a reversible inhibitor of both free thrombin and thrombin bound to fibrin. This reversibility is possible because the bound bivalirudin undergoes cleavage at the second N-terminal proline to release the portion of the drug bound to the active site. The carboxyl-terminal portion of bivalirudin dissociates from thrombin to regenerate thrombin. Bivalirudin does not bind to plasma protein.

Bivalirudin is administered via intravenous bolus injection, followed by continuous infusion (Table 31.4). The drug exhibits a rapid onset and a short duration of action. Bivalirudin is eliminated by renal excretion. It has been suggested that dosage adjustments be made in patients with severe renal impairment and in patients undergoing dialysis. Approximately 30% is eliminated unchanged along with proteolytic cleavage products. Because of the reversible nature of bivalirudin the drug exhibits less risk of bleeding than other antithrombotics, and there have been no reported cases of antibody formation to bivalirudin.

Bivalirudin, a 20-amino-acid peptide, has been approved for use in patients with unstable angina undergoing percutaneous coronary intervention.

Potentially hazardous interactions with other drugs
Analgesics: increased risk of haemorrhage with IV diclofenac and ketorolac.
Antiplatelets and anticoagulants: increased risk of bleeding. Thrombolytics: may increase risk of bleeding complications; enhance effect of bivalirudin.

As a peptide, bivalirudin is expected to undergo catabolism to its constituent amino acids, with subsequent recycling of the amino acid in the body pool. Bivalirudin is metabolised by proteases, including thrombin. The primary metabolite resulting from the cleavage of Arg3 -Pro4 bond of the N-terminal sequence by thrombin is not active because of the loss of affinity to the catalytic active site of thrombin.

[1]. shammas n w. bivalirudin: pharmacology and clinical applications[j]. cardiovascular drug reviews, 2005, 23(4): 345-360.