Ancrod is an anticoagulant purified from the venom of the Malayan pit viper that functions by inactivating circulating plasma fibrinogen. Not currently approved for use or marketed in any country.

Generic Name
DrugBank Accession Number

Ancrod, marketed as Viprinex, is a defibrinogenating agent derived from Malayan pit viper venom. The defribrinogenation of blood results in an anticoagulant effect. Currently, Viprinex®/ancrod is not approved or marketed in any country, but is being investigated as a stroke treatment in worldwide clinical trials. In January 2005, the U.S. FDA granted a 'fast-track status' for investigation of ancrod use in patients suffering from acute ischemic stroke, a life threatening condition caused by the blockage of blood vessels supplying blood and oxygen to portions of the brain, for which phase III trials are currently being conducted.

Approved, Investigational
  • Ancrod



Ancrod is indicated for the treatment of deep vein thrombosis (DVT), central retinal branch vein thrombosis, pripaism, pulmonary hypertension of embolic origin, embolism after insertion of prosthetic cardiac valves, rethrombosis after thrombolytic therapy, rethrombosis after vascular surgery, and prevention of DVT after repair of a fractured neck of a femur.

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Contraindications & Blackbox Warnings
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The decreased viscosity is directly attributable to lowered fibrinogen levels and leads to important improvements in blood flow and perfusion of the microcirculation. Ancrod decreases the blood viscosity in affected arteries, leads to less intense pain, improves physical limb mobility, facilitates physical and ergo therapy, and decreases the likelihood of local thrombotic events.

Mechanism of action

Ancrod's anticoagulant effects are through the rapid removal of fibrinogen from the blood within hours following ancrod administration. Ancrod specifically cleaves only the alpha chain of fibrinogen, producing the characteristic fibrinopeptides A, AP and AY, not the B-fibrinopeptide. The resulting fibrin polymers are imperfectly formed and much smaller in size (1 to 2 ┬Ám long) than the fibrin polymers produced by the action of thrombin. These ancrod-induced microthrombi are friable, unstable, urea-soluble and have significantly degraded a-chains. They do not cross-link to form thrombi. They are markedly susceptible to digestion by plasmin and are rapidly removed from circulation by either reticuloendothelial phagocytosis or normal fibrinolysis, or both. Blood viscosity is reduced by 30-40%. Ancrod does not activate plagminogen and does not degrade preformed, fully cross-linked thrombin fibrin. Consequently, unlike fibrinolytic agents, ancrod can be used postoperatively. Ancrod does not activate Factor XIII, produce platelet aggregation, or release ADP, ATP, potassium, or serotonin from platelets.

UFibrinogen alpha chainNot AvailableHumans

100% after i.v. dosing

Volume of distribution

Not Available

Protein binding

95% bound to erythrocytes

Not Available
Route of elimination

Not Available


3 to 5 hours


Not Available

Adverse Effects
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Currently, a new dosing strategy is being investigated in two international phase III trials as part of the 'Ancrod Stroke Program (ASP).' Each of these studies will enroll 650 patients and assess whether a brief, relatively rapid ancrod infusion with no maintenance dosing will be both effective and safe.

Ancrod is contraindicated in patients with known bleeding disorders, unexplained excessive bleeding in the past, platelet counts <100,000 except for Heparin-induced thrombocytopenia, planned surgery, active GIT ulcerations, malignant disease, renal stones, uncontrolled arterial hypertension, active pulmonary tuberculosis, impaired fibrinolysis, severe liver disease, shock, or impending shock. Ancrod should not be given shortly before delivery or via the intramuscular route.

Ancrod has been listed as pregnancy category X by the FDA. Ancrod should not be used in pregnancy as it may interfere with implantation. It is not teratogenic in animal studies but there were some fetal deaths from placental hemorrhage.

Side effects may include hypersensitivity reactions and pain at the injection site.

Not Available
Pharmacogenomic Effects/ADRs
Not Available


Drug Interactions
This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.
AbciximabThe risk or severity of bleeding can be increased when Abciximab is combined with Ancrod.
AceclofenacThe risk or severity of bleeding and hemorrhage can be increased when Aceclofenac is combined with Ancrod.
AcemetacinThe risk or severity of bleeding and hemorrhage can be increased when Ancrod is combined with Acemetacin.
AcenocoumarolThe risk or severity of bleeding can be increased when Acenocoumarol is combined with Ancrod.
Acetylsalicylic acidAcetylsalicylic acid may increase the anticoagulant activities of Ancrod.
Food Interactions
  • Avoid herbs and supplements with anticoagulant/antiplatelet activity. Examples include garlic, ginger, bilberry, danshen, piracetam, and ginkgo biloba.


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Brand Name Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing EndRegionImage
ViprinexLiquid70 unit / mLIntravenous; SubcutaneousAbbott1986-12-312007-07-31Canada flag


ATC Codes
B01AD09 — Ancrod
Drug Categories
Not classified
Affected organisms
Not Available

Chemical Identifiers

CAS number


General References
  1. Hennerici MG, Kay R, Bogousslavsky J, Lenzi GL, Verstraete M, Orgogozo JM: Intravenous ancrod for acute ischaemic stroke in the European Stroke Treatment with Ancrod Trial: a randomised controlled trial. Lancet. 2006 Nov 25;368(9550):1871-8. [Article]
  2. Kelton JG, Smith JW, Moffatt D, Santos A, Horsewood P: The interaction of ancrod with human platelets. Platelets. 1999;10(1):24-9. [Article]
PubChem Substance

Clinical Trials

Clinical Trials
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PhaseStatusPurposeConditionsCountStart DateWhy Stopped100+ additional columns
3CompletedNot AvailableCerebral Ischemia / Infarction, Brain / Stroke, Acute1somestatusstop reasonjust information to hide
3TerminatedTreatmentCerebral Ischemia / Infarction, Brain / Stroke2somestatusstop reasonjust information to hide
1, 2CompletedTreatmentDeafness / Ear Diseases / Hearing Disorders / Hearing loss or impairment / Sensorineural Hearing Loss1somestatusstop reasonjust information to hide


Not Available
Not Available
Dosage Forms
LiquidIntravenous; Subcutaneous70 unit / mL
Not Available
Not Available


Experimental Properties
Not Available


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Pharmacological action
General Function
Structural molecule activity
Specific Function
Cleaved by the protease thrombin to yield monomers which, together with fibrinogen beta (FGB) and fibrinogen gamma (FGG), polymerize to form an insoluble fibrin matrix. Fibrin has a major function ...
Gene Name
Uniprot ID
Uniprot Name
Fibrinogen alpha chain
Molecular Weight
94972.455 Da

Drug created at October 21, 2007 22:23 / Updated at February 21, 2021 18:51