Polyvalent snake antivenom (Bothrops and Crotalus) !
Horse antivenom from Colombia's INS against the venom of Bothrops (mapaná, taya equis, terciopelo) and Crotalus (rattlesnake). Given intravenously.
Updated 2026-11-01
Also called: Polyvalent anti-snake antivenom, Anti-Bothrops/anti-Crotalus antivenom
The figure shows a phospholipase A2-like myotoxin from Bothrops asper venom, one of the components the antivenom neutralises.
Mechanism of action
It is specific equine IgG, purified from the plasma of horses immunised with Bothrops and Crotalus venoms from different regions of Colombia. The antibodies bind circulating toxins: in Bothrops, enzymes that consume clotting factors and cause bleeding, and toxins that damage local tissue; in Crotalus, neurotoxic and myotoxic phospholipases. It does not reverse tissue damage already done.
- Injected venom releases enzymes and toxins into the blood
- Equine IgG binds the circulating toxins
- Coagulopathy is corrected and systemic damage halted
- Local necrosis already established is not reversed
Pharmacokinetics
- Distribution
- Intravenous; whole IgG, which stays in the plasma where clotting-disrupting toxins act
Indications
- Bothrops envenoming (mapaná, taya equis, terciopelo and related species) with local or systemic signs
- Crotalus (rattlesnake) envenoming
Adverse effects
Common
- Early reactions: urticaria, itching, fever
- Pyrogenic reactions (chills and fever) during the infusion
Contraindications
- No absolute contraindication in envenoming that needs it; a history of reaction to equine sera requires readiness to treat anaphylaxis
Key interactions
- Adrenaline (epinephrine)
- The treatment for antivenom anaphylaxis; it must be available before the infusion starts
What is monitored
- Clotting tests and platelet count to judge response
- Limb circumference and spread of local swelling
- Kidney function and urine (myoglobinuria in Crotalus)
- Continuous vital signs during the infusion
Administration and safety
- Intravenous only, under continuous medical supervision
- Store refrigerated (2–8 °C) as the manufacturer states
- Have adrenaline and anaphylaxis equipment ready before starting
- Record the batch given and notify the case to the surveillance system
Nursing care
- Avoid unnecessary movement of the limb; no tourniquets, incisions or suction
- Monitor vital signs and signs of anaphylaxis throughout the infusion
- Measure limb circumference and watch for bleeding from gums, urine or puncture sites
- Explain the symptoms of serum sickness that can appear weeks later
Pregnancy and breastfeeding
Severe envenoming endangers mother and fetus; pregnancy does not prevent antivenom when it is indicated.
Test yourself
Think of the answer, then tap the question to see it.
Against which snake genera is the INS polyvalent antivenom indicated?
Bothrops (mapaná, equis and related species) and Crotalus (rattlesnake).
What is the INS polyvalent snake antivenom made of?
Specific IgG purified from the plasma of horses immunised with Bothrops and Crotalus venoms.
Why does antivenom not reverse established local necrosis?
Antibodies neutralise free toxins; cell damage already done in tissue is not undone, which is why early treatment matters.
Related drugs
← Back to the class: Antivenoms
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Venta de Antivenenos (Instituto Nacional de Salud (Colombia), 2026); Snakebite envenoming (World Health Organization, 2026); Guidelines for the production, control and regulation of snake antivenom immunoglobulins, Annex 5, TRS No 1004 (World Health Organization, 2017); Farmacología básica y clínica (Katzung), ch. 58 (McGraw Hill, 2025).
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Representative model, for educational purposes only.