Snake Venom Antiserum

Indications

Snake Venom Antiserum is used for: Snake Venom Antiserum is indicated for bites caused by Cobra, Common Krait, Russell's Viper and Saw-Scaled Viper, where the patient presents with one or more of fallowing visible clinical signs and symptoms of envenomation – 1. Local envenomation- a) Presence of bite marks with or without oozing of blood, blistering and change in color of skin. b) Rapidly progressive or massive swelling involving more than half of the bitten limb within few hours of bite (without tourniquet) c) Development of enlarged tender lymph nodes draining the bitten part within couple of hours after bite 2. Systemic envenomation- a) Neurotoxic syndrome- signs of neuro-paralysis like blurring of vision, double vision, and difficulty in swallowing, sleepy feeling, drooping of head, slurring of speech and the voice may become indistinct with shallow breathing, ptosis, ataxia, respiratory paralysis and generalized flaccid paralysis. b) Hemotoxic syndrome- spontaneous systemic bleeding, nausea, vomiting, abdominal pain and abdominal tenderness suggestive of gastro-intestinal or retro-peritoneal bleed and/or renal damage, coagulopathy detected by 20 min WBCT with or without external bleeding and shock.

Adult Dose

Initial dose depends upon an estimate of the amount of envenomation as mentioned below: 1. Minimal Envenomation -Progressive local swelling but no systemic symptoms. 5 vials (50ml) is recommended to be administered. 2. Moderate Envenomation -Swelling beyond the site of the bite, mild systemic symptoms, and/or hematologic and coagulation abnormalities are present. 5 to 10 vials (50 to 100ml) is recommended to be administered. 3. Severe Envenomation -Rapidly progressive and extensive local effects, systemic symptoms and evidence of hemolysis or coagulopathy. 10 to 20 vials (100 -200ml) or more is recommended to be administered.

Child Dose

In children and small adults (body weight less than 40kg) upto 50% more doses of Snake Venom Antiserum is recommended to be administered.

Renal Dose

Administration

Snake Venom Antiserum is administered intravenously either undiluted at the rate of not more than 1ml per minute or is diluted in 500ml of intravenous fluid (either Sodium Chloride Injection or 5% Dextrose Injection) and administered as rapidly as tolerated over 1-2 hours. While diluting the Snake Venom Antiserum, mix by gentle swirling rather than shaking to avoid foaming. Additional infusions should be repeated hourly until progressive swelling in the bitten part ceases and systemic signs and symptoms disappear. When an adequate dosage is achieved, the improvement in patient's clinical signs are often seen.

Contra Indications

There are no known contraindications for the administration of Antivenom. Person who is proven to be allergic to equine antisera.

Precautions

Proper precautions are necessary while dealing with persons with a known hypersensitivity to constituents of product. Few doctors prefer to premedicate patients with Inj. Adrenaline 0.25 ml s/c to prevent possibility of adverse reactions. In haemotoxic bites, IM injections should be avoided till correction of coagulopathy to avoid formation of haematoma and oozing of blood. Not for local administration on bitten area. In patients having tourniquet, it should be released slowly only after start of Antivenom administration. Considering the risk associated with snake bite envenomation, pregnancy is not a contraindication for the administration of Snake Venom Antiserum subsequent to bite.

Pregnancy-Lactation

Interactions

Increased risk of hypoglycaemia when used in combination w/ sulfonylureas or insulin.

Adverse Effects

Side effects of Snake Venom Antiserum : The immediate reaction (shock & anaphylaxis) usually occurs within 30 minutes. Symptoms and signs may develop before the needle is withdrawn and include urticaria, itching, fever, chills or rigor, nausea, vomiting, diarrhoea, abdominal cramps, tachycardia, hypotension, bronchospasm, and angioedema. Serum sickness usually occurs 5 to 24 days after administration. The usual symptoms and signs are fever, urticaria, edema, nausea and vomiting. Occasionally neurological manifestations develop. Pain and muscle weakness are frequently present.

Mechanism of Action

Passive immunization, antivenoms are in- jected to neutralize snake venoms in the patient’s blood circulation.