Crotalus scutulatus antivenin



Crotalus scutulatus antivenin is a mixture of antibodies used to treat venomous snake bites from Crotalus scutulatus (Mojave rattlesnake).

Brand Names
Generic Name
Crotalus scutulatus antivenin
DrugBank Accession Number

Crotalus scutulatus antivenin is derived and purified immunoglobulin fragments obtained from other domestic animals such as sheep previously immunized with Crotalus scutulatus (also known as the Mojave rattlesnake 2).

The final purified antivenin product is obtained by mixing other different monospecific snake antivenins and isolating the antivenin of interest through fractionation and chromatography techniques. It is intravenously administered to limit systemic toxicity Label, 3, 4.

CROFAB (crotalidae polyvalent immune fab (ovine))is a sheep-derived antivenin used for the management of adult and pediatric patients with North American crotalid envenomation Label, which includes the Crotalus scutulatus snake (Mojave snake).

Mojave rattlesnakes inhabit desert areas of the southwestern United States and central Mexico. Specimens with type A venom, which cause a different pattern of injury than other rattlesnakes, have been reported in southern California, Nevada, Utah, Arizona, Texas, and New Mexico 2.

Since it was approved by the Food and Drug Administration in October 2000, crotalidae poyvalent immune Fab (CroFab) has largely replaced previously used crotaline antivenom. CroFab is more specifically tailored for crotalids of North America and is less allergenic than whole immunoglobulin antivenoms 7.

Approved, Experimental
Biologic Classification
Protein Based Therapies
Other protein based therapies
Protein Chemical Formula
Not Available
Protein Average Weight
Not Available
Not Available
  • Crotalus scutulatus immune fab antivenin (ovine)



CROFAB is indicated for the management of adult and pediatric patients with North American crotalid envenomation. The term crotalid is used to describe the Crotalinae subfamily (formerly known as Crotalidae) of venomous snakes which includes rattlesnakes, copperheads and cottonmouths/water moccasins Label.

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Associated Conditions
Contraindications & Blackbox Warnings
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Acts as an antivenin, relieving symptoms of envenomation from Crotalinae family of snakes, and preventing lethal consequences of snake evenomation Label.

The Crotalidae family produces venoms which are generally necrolytic and hemolyzing to tissues. Hemorrhagins in crotalid venom is toxic to the blood vessels and therefore cause hemorrhage and edema at the wound site, in addition to systemic hemorrhage and shock. Significant anemia is observed due to hemolysis and extravasation of blood due to damaged vessels. Disseminated intravascular coagulation (DIC) has been observed in some cases. The most frequent initial clinical pathological changes include echinocytosis, thrombocytopenia, leukocytosis and prolonged activated clotting time. In general, edema and erythema along with fang marks (_Crotalidae _family) may be seen at the site of bite although it is tough to identify due to thick hair coat in animals 8.

Patients sustaining rattlesnake envenomation often develop thrombocytopenia, the etiology of which is not clear. It has been shown thatCrotaline Fab antivenom improved platelet aggregation in an in vitro model of platelet dysfunction induced by venom from C. scutulatus 1.

Mechanism of action

CROFAB is a venom-specific Fab fragment of immunoglobulin G (IgG) that works by binding and neutralizing venom toxins, facilitating their redistribution away from target tissues and their elimination from the body Label


Not Available

Volume of distribution

0.3 L/kg Label

Protein binding

Not Available

Not Available
Route of elimination

Not Available


Approximately 15 hours Label


32 mL/min (approximately 0.4 mL/min/kg) Label

Adverse Effects
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Ed50 for the Crotolus scutulatus snake evenomation is 8 mg antivenin/mg venom Label.

Most common adverse reactions (incidence ≥5% of subjects) were urticaria, rash nausea, pruritus and back pain. Hypersensitivity reactions may also occur Label.

Hypersensitivity reactions can occur to substances derived from sheep plasma; anaphylaxis and anaphylactoid reactions are possible, especially in patients with known allergies to sheep protein. Immediate treatment (including epinephrine 1 mg/mL) for anaphylaxis and/or hypersensitivity reactions must be available prior to administration. In cases of acute hypersensitivity reactions, including anaphylaxis and anaphylactoid reactions, discontinue infusion and institute appropriate emergency treatment. Sensitization may occur with repeated doses of antivenin 5.

Drugs, such as crotalidae antivenin which are processed with papain, may lead to hypersensitivity reactions in patients allergic to papaya, other papaya extracts, papain, chymopapain, or the pineapple-enzyme bromelain. There may also be cross-allergenicity with dust mite and latex allergens 5.

Late serum reactions (rash, pruritus, urticaria, or serum sickness consisting of severe rash and pruritus) reported in 12% (5/42) of patients in initial clinical trials have been observed and delayed hypersensitivity or serum sickness reported in 5–11% of patients in other studies 5.

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.
Not Available
Food Interactions
No interactions found.


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Mixture Products
NameIngredientsDosageRouteLabellerMarketing StartMarketing EndRegionImage
CroFabCrotalus scutulatus antivenin (1 g/1) + Agkistrodon piscivorus antivenin (1 g/1) + Crotalus adamanteus antivenin (1 g/1) + Crotalus atrox antivenin (1 g/1)Injection, powder, lyophilized, for solutionIntravenousBTG International Inc.2000-02-10Not applicableUS flag


Drug Categories
Chemical TaxonomyProvided by Classyfire
Not Available
Organic Compounds
Super Class
Organic Acids
Carboxylic Acids and Derivatives
Sub Class
Amino Acids, Peptides, and Analogues
Direct Parent
Alternative Parents
Not Available
Not Available
Molecular Framework
Not Available
External Descriptors
Not Available
Affected organisms
  • Humans

Chemical Identifiers

CAS number
Not Available


General References
  1. Carstairs SD, Kreshak AA, Tanen DA: Crotaline Fab antivenom reverses platelet dysfunction induced by Crotalus scutulatus venom: an in vitro study. Acad Emerg Med. 2013 May;20(5):522-5. doi: 10.1111/acem.12135. [Article]
  2. Mojave Rattlesnake Envenomation [Link]
  3. Crotalidae Polyvalent Immune Fab [Link]
  4. [Link]
  5. Crotalidae polyvalent immune fab [Link]
  6. Mayo clinic: Antivenin (crotalidae) [Link]
  7. Safety and Efficacy of Crotalidae Polyvalent Immune Fab in Pediatric Crotaline Envenomations [Link]
  8. Review of Agkistrodon-Piscivorus [Link]
PubChem Substance
FDA label
Download (407 KB)

Clinical Trials

Clinical Trials
4CompletedTreatmentSnake Bite1
4TerminatedTreatmentSnake Envenomation1
3CompletedTreatmentSnake Bite1
2CompletedTreatmentCoagulation Disorder / Snake Bite1


Not Available
Not Available
Dosage Forms
Injection, powder, lyophilized, for solutionIntravenous
Not Available
Not Available


Not Available
Experimental Properties
Not Available

Drug created at September 08, 2017 20:22 / Updated at June 19, 2021 00:27