Crotalid AntivenomCrotalid Antivenom – F(ab’)2 Antivenom

BioVeteria is developing a new veterinary F(ab’)2 snake antivenom (rattlesnake antivenom, rattlesnake antivenin) produced by Veteria Labs S.A. de C.V. in Mexico City, Mexico.  The polyvalent snake antivenom consists of F(ab’)2 fragments derived from horses hyperimmunized against snake venoms of Crotalus durissus and Bothrops asper.  BioVeteria’s antivenom is lyophilized and has rapid reconstitution properties.

F(ab’)2 antivenoms are produced by enzymatically digesting whole Immunoglobulin G (IgG) into fragments, and removing the Fc (Fragment crystallizable) from the molecule.  F(ab’)2 fragments have two antigen (venom toxin) binding regions compared to the smaller Fab antivenom compositions.  In addition, the Fc portion of the IgG molecule is removed in this process to reduce or eliminate Fc receptor binding on immune cells.

Snake Antivenom Terms and Commonly Used Language
Crotalidae (Crotalinae) – the family of snakes consisting of pit vipers.
Antivenom – (antivenin, antivenene) – A substance that is active against the venom of a snake, spider, scorpion, or other venomous animal or insect.
IgG – Immunoglobulin G
Fab – Fragment antigen binding – the region on IgG that binds an antigen (venom toxin)
F(ab’)2 – Dimer of Fab
Fc – Fragment crystallizable – portion of IgG that binds Fc receptors
Fc receptor – a membrane bound protein found on various immune cells and certain compliment proteins

Pit Vipers are in the Crotalinae family of snakes.  Pit Vipers in the United States consist of three genera, being:
Crotalus spp: Common names are rattlesnakes or rattlers.
Agkistrodon spp: Common names are moccasins, copperheads, or cantils.
Sistrurus spp: Common names are ground rattlesnakes, pigmy rattlesnakes, or massasaugas.

NOTE: This antivenom product is not yet approved in the United States. Veterinarians must obtain the appropriate import permits and should comply with any state and federal regulations associated with antivenom imports. BioVeteria does not sell this antivenom in the United States, but is working towards the approval. Additional information regarding importation of a foreign veterinary biologic is contained in Veterinary Services Memorandum 800.101 under the Veterinary Services Memorandums Section of “Regulations and Guidance” at You should be aware that application for an Import Permit does not necessarily imply immediate issuance of the Import Permit or that additional information will not be required.

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