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Antivenom Injection contains Snake Venom Antiserum
Antivenom Injection uses for
Snake Venom Antiserum lyophilized is a refined and concentrated preparation of serum globulins for intravenous administration, containing equine immunoglobulin fragments F(ab') 2 , obtained from the plasma of healthy equines, hyperimmunized against venoms of above species of snakes. In addition, it also contains the anti-microbial agent: cresol.
Each vial contains lyophilized preparation of Snake Venom Antiserum. After reconstitution each ml Snake Venom Antiserum neutralizes not less than Cobra venom (Naja naja) 0.60 mg, Common Krait venom (Bungarus caeruleus) 0.45 mg, Russell's Viper venom (Vipera russelli) 0.60 mg, Saw scaled Viper venom (Echis carinatus) 0.45 mg.
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 –
Local envenomation-
- Presence of bite marks with or without oozing of blood, blistering and change in color of skin.
- Rapidly progressive or massive swelling involving more than half of the bitten limb within few hours of bite (without tourniquet)
- Development of enlarged tender lymph nodes draining the bitten part within couple of hours after bite
Systemic envenomation-
- 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.
- 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.
Immediate actions and first aid: Quick and positive measures should be taken to meet the emergency. Do not try to catch or kill the snake without proper tools and avoid unnecessary exposure to snack. Patient should be removed to a well-ventilated and quiet place and restrict his/her movement. Patient should be reassured to overcome fear. Immobilize the bitten part by applying immobilization bandage as done for a fracture and bitten part is kept below heart level. Ligation by applying tourniquets should be avoided, however, if applied it should be tied at moderate distance above the bitten part to prevent the entry of venom into the circulation. Patient should be immediately taken to nearby medical centre for treatment without loss of time.
As of now Snake venom antiserum is the only specific antidote for snake envenomation and prompt administration of adequate dose of Antiserum is of paramount importance for neutralization of unbound circulating snake venom components for early response to treatment. Any delay in administration may result in increased dose requirement and decreased effectiveness. As the clinical signs can vary due to many factors such as type of snake, time of reporting after bite, size of snake, amount of venom injected during bite, seasonal & regional variation in venom composition etc., no accurate dosage can be recommended.
However, considering the average quantity of venom injected by snake at the time of bite and degree of envenomation, it is recommended to administer initial dose of 50 vials of Snake venom antiserum by slow intravenous infusion either undiluted at a speed of not more than 2 ml per minute or after dilution with Normal /glucose saline at a rate of 50 ml/kg body weight over one hour. Children should receive the same dose as adults. Constant monitoring of the vital signs at frequent intervals during initial 1 hour is recommended. Requirement of further dosing depends on extent of reversal of coagulopathy confirmed after 6 hours of Antiserum administration by WBCT in haemotoxic bite or if symptoms persist or worsen or in respiratory failure in neurotoxic bite after 1 hour of Antiserum administration.
If the blood is still in coagulable or no signs of reversal of paralysis are seen, a further dose of 5 to 10 vials of Antiserum should be administered by slow IV route only. Administration by IM or locally around the bite wound is not recommended. In the majority of cases of both neurotoxic and haemotoxic bites, total dose of 150 vials is adequate unless a proven recurrence of envenomation is established. In such a scenario, further doses can be given as per clinical condition of the patient. Hypersensitivity skin test has no predictability value and hence should not be used.
To reconstitute the Snake Venom Antiserum, transfer content of supplied diluents into the vial containing lyophilized preparation. Mix the contents gently by swirling action and avoid vigorous shaking. Serum should be used as soon as possible after reconstitution.
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