Antivenom

• Treatment of systemic envenomation caused by venomous snakes, especially bites from the "big four" venomous snakes in South Asia:
• Indian Cobra (Naja naja)
• Common Krait (Bungarus caeruleus)
• Russell’s Viper (Daboia russelii)
• Saw-scaled Viper (Echis carinatus)
• Indicated for neutralization of circulating venom toxins to prevent or reverse neurotoxic, hemotoxic, and cytotoxic effects of snakebite.
• Use in moderate to severe snake envenomation presenting with signs such as coagulopathy, neurotoxicity, local tissue necrosis, or systemic symptoms.

• Route: Intravenous infusion only; intramuscular route is not recommended.
• Initial Dose: 8–10 vials diluted in normal saline; infused slowly over 30 to 60 minutes.
• Repeat Doses: Additional 4–10 vials may be given depending on clinical response and persistence of symptoms.
• Maximum Dose: Generally up to 20 vials in 24 hours depending on severity.
• Pediatrics and Adults: Same dosing regimen; dosing guided by clinical severity, not weight-based.
• Elderly and special populations: Use with caution; monitor for adverse reactions; no dose adjustment required based on age.
• Monitoring: Continuous vital signs and allergic reaction monitoring during infusion.

Snake Venom Antiserum contains polyclonal antibodies derived from immunized horses that specifically bind and neutralize venom toxins circulating in the bloodstream. By forming immune complexes with venom components such as neurotoxins, hemotoxins, and cytotoxins, the antiserum prevents these toxins from interacting with target tissues and enzymes. This neutralization halts the progression of systemic toxicity, allowing restoration of normal physiological function and preventing further tissue damage.

• Absorption: Immediate systemic availability following intravenous administration.
• Distribution: Rapid distribution in extracellular fluid compartments; targets circulating venom toxins.
• Metabolism: Degraded by proteolytic enzymes in the reticuloendothelial system.
• Elimination: Antibodies cleared via hepatic and renal pathways.
• Half-life: Variable; typically 60 to 100 hours depending on antibody subclass and individual patient factors.
• Onset of Action: Clinical improvement usually observed within 30–60 minutes post-infusion.

• Pregnancy: No well-controlled human studies; use only if potential benefits justify the risks. The urgency of treating snakebite usually outweighs theoretical risks to the fetus.
• Lactation: It is unknown whether antivenom antibodies are excreted in human milk. Due to the protein nature and digestion in infants, systemic effects are unlikely. Use with caution.

• Primary Class: Antivenom / Antitoxin
• Subclass: Equine-derived polyvalent snake antivenom

• Known hypersensitivity or allergy to equine proteins or antivenom constituents.
• Previous severe allergic reaction to any antivenom preparation.
• Caution in patients with immune disorders or history of serum sickness.

• High risk of anaphylaxis and hypersensitivity reactions; emergency resuscitation equipment and epinephrine must be immediately available.
• Monitor closely for early signs of allergic reaction during infusion (urticaria, bronchospasm, hypotension).
• Serum sickness can develop 5–14 days post-treatment, presenting with fever, rash, arthralgia, and lymphadenopathy.
• Use caution in patients with renal or hepatic impairment due to increased risk of adverse reactions.
• Avoid intramuscular administration due to poor absorption and increased risk of tissue reaction.
• Skin testing is not recommended due to poor predictive value.

• Common: Fever, chills, rash, itching, nausea, vomiting.
• Serious: Anaphylaxis (bronchospasm, hypotension), serum sickness, angioedema.
• Rare: Acute renal failure (usually venom-induced), immune complex-mediated reactions.

• No significant pharmacokinetic interactions expected.
• Epinephrine, corticosteroids, and antihistamines may be used to manage hypersensitivity reactions.
• Avoid concurrent administration of live vaccines shortly after antivenom due to potential immunoglobulin interference.

• WHO guidelines emphasize early administration of polyvalent antivenom for better clinical outcomes.
• Recent regional protocols recommend intravenous infusion only and discourage skin testing.
• Emphasis on monitoring and management of hypersensitivity reactions during treatment.

• Store refrigerated at 2°C to 8°C.
• Protect from light and moisture.
• Do not freeze.
• Use immediately after reconstitution with sterile water.
• Shelf life typically 2–3 years unopened.