Snake Venom Antiserum is indicated for the treatment of bites caused by Cobra, Common Krait, Russell’s Viper, and Saw-Scaled Viper when the patient shows one or more clinical signs and symptoms of envenomation.

Local envenomation:

• Bite marks present with or without bleeding, blister formation, and discoloration of the skin
• Rapidly increasing or extensive swelling involving more than half of the affected limb within a few hours (without tourniquet)
• Enlargement of tender lymph nodes draining the bitten area within a few hours

Systemic envenomation:

• Neurotoxic syndrome: symptoms of nerve paralysis such as blurred or double vision, difficulty swallowing, drowsiness, drooping of the head, slurred or indistinct speech, shallow breathing, ptosis, ataxia, respiratory paralysis, and generalized flaccid paralysis
• Hemotoxic syndrome: spontaneous bleeding, nausea, vomiting, abdominal pain and tenderness suggesting gastrointestinal or retroperitoneal bleeding and/or kidney damage, coagulation abnormalities detected by 20-minute WBCT with or without external bleeding and shock

Immediate actions and first aid: Take prompt and appropriate emergency measures. Do not attempt to catch or kill the snake. Move the patient to a calm, well-ventilated area and limit movement. Reassure the patient to reduce fear. Immobilize the affected limb using a splint or bandage as for a fracture and keep it below heart level. Avoid using a tourniquet; if applied, it should be loose and above the bite site. Transport the patient immediately to the nearest medical facility without delay.

Snake Venom Antiserum (lyophilized) is a purified and concentrated preparation of serum globulins intended for intravenous use. It contains equine immunoglobulin fragments F(ab')₂ derived from the plasma of healthy horses immunized against the venoms of the above snake species. It also includes cresol as an antimicrobial preservative.

Each vial contains a lyophilized form of Snake Venom Antiserum. After reconstitution, each ml neutralizes at least: Cobra venom (Naja naja) 0.60 mg, Common Krait venom (Bungarus caeruleus) 0.45 mg, Russell’s Viper venom (Vipera russelii) 0.60 mg, and Saw-scaled Viper venom (Echis carinatus) 0.45 mg.

Snake venom antiserum is a sterile preparation containing antitoxin globulins and their derivatives. It is the only specific treatment for venomous snakebite.

Snake venom antiserum is the only specific antidote for snake envenomation. Early and prompt administration of an adequate dose is essential to neutralize circulating venom and ensure effective treatment. Delay in administration may increase the required dose and reduce effectiveness. Since clinical presentation varies depending on factors such as snake species, time elapsed after the bite, size of the snake, amount of venom injected, and regional or seasonal variations, an exact fixed dosage cannot be defined.

Based on the average venom load and severity of envenomation, an initial dose of 5–10 vials is recommended. This should be administered by slow intravenous infusion, either undiluted at a rate not exceeding 2 ml per minute, or diluted in normal saline or glucose solution at a rate of 5–10 ml/kg body weight over one hour. Children should receive the same dose as adults. Vital signs should be monitored frequently during the first hour. Further dosing depends on clinical response, including reversal of coagulation abnormalities (confirmed by WBCT after 6 hours in hemotoxic bites) or improvement in neurotoxic symptoms.

If blood remains incoagulable or paralysis does not improve, an additional 5–10 vials should be administered via slow IV infusion. Intramuscular or local infiltration around the bite site is not recommended. In most neurotoxic and hemotoxic cases, a total dose of 15–20 vials is usually sufficient unless there is recurrence of envenomation. Additional doses may be given based on the patient’s clinical condition. Hypersensitivity skin testing is not reliable and should not be performed.

Use with β-adrenergic blockers may increase the risk and severity of acute anaphylactic reactions.

There are no known contraindications for the use of antivenom.

Snake venom antiserum, being derived from equine sources, may cause early or delayed hypersensitivity reactions. Adrenaline should always be kept readily available before administering the antiserum. The incidence of adverse reactions can be reduced by proper dilution with saline and controlling the infusion rate.

Considering the serious risk associated with snakebite envenomation, pregnancy is not a contraindication for administering snake venom antiserum after a bite.

Caution should be exercised in patients with known hypersensitivity to any component of the product. Some clinicians may choose to premedicate with Inj. Adrenaline (0.25 ml) to reduce the risk of adverse reactions. In hemotoxic envenomation, intramuscular injections should be avoided until coagulation is corrected to prevent hematoma formation and bleeding. If a tourniquet has been applied, it should be released gradually after starting antivenom administration.

Vaccines, Anti-sera & Immunoglobulin

Lyophilized Snake Venom Antiserum can be stored at room temperature and does not require special storage conditions. Ideally, it should be kept in a cool, dark place and protected from excessive heat.