PREAMBLE:

              Snake Antivenin is of equine origin derived from the plasma of the Horse, Ponies, Mules etc. that have been  hyperimmunized against the venoms of the four most common venomous snakes of  India. namely 1) Indian Cobra (Naja naja ) 2) Common krait (Bangarus caeruleus) 3) Russell's Viper (Vipera russellii ) and 4) Saw Scaled Viper (Echis carinatus). Serum Obtained from the plasma contains Purified,enzyme-refined and concentrated specific heterologous immunoglobulins. It is used as a passive   immunising agent and affords protection to the suseptible victims against the bites of the snake species mentioned above.

          1 ml. of the reconstituted Snake Antivenin neutralises 0.6 mg. of the Indian cobra venom,0.45 mg. of common krait venom, 0.6 mg. of Russell's Viper venom and 0.45 mg. of the saw-scaled viper venom.

Direction for Use :
A. Indications :
The Snake Antivenin is indicated for all bites caused by  1. Indian Cobra 2. Common krait 3. Russell's viper and 4. Saw-scaled viper, where the patients present with clinical signs and symptoms of envenomation.

B. Precautions to be observed before administration of snake Antivenin:
1. Elicit history of familiar allergic disorders such as asthma, eczema, drug allergy from the patient.
2. Whether he had received earlier, injection of serum such as anti-tetanus serum, anti-diphtheria serum etc.
3. Carry out the sensitivity test on the patient. Inject subcutaneously 0.1ml of the serum diluted 1:10. Observe the patient for 30 min. for local or general reactions, if any. In the absense of adverse reaction, administer the requisite dose by the chosen route of injection.
4. Keep handy injection Adrenaline (Epinephrine) 1ml of 1:1000 along with antihistamines and steroids to meet any emergency arising out of sensitivity reactions.
5. After administering the full dose of serum, the patient should be kept under observation for at least 30 min.
6. If a patient is found sensitive to the equine antiserum, you may desensitise him by administering graded doses of antiserum at regular and adequate intervals. Before desensitising the patient, the doctor has to decide whether serotherapy is really needed.
7. In sensitive individuals where time factor is of paramount importance, it is advisable to administer snake antivenin under the cover of injection. Adreneline (Epinephrine) 1ml (1:1000) i.m. and antihistaminics, without awaiting results of the test dose.

C. Contraindication
There are no known contraindications for the administration of snake antivenin.

D. Adverse Drug Reactions
This serum being heterologous, is liable to cause sensitivity reactions in occasional patient. The immediate reaction is anaphylatic shock (immediate hyper-sensitivity) characterised by sweating, pallor, broncho-spasm, laryngo-spasm, hypotension leading to shock, coma and death. Treatment consist of prompt administration of injection epinephrine, steroids and anti-histamines along with ancillary measures such as endotracheal intubation, oxygen-therapy and treatment of shock.
A late serum sickness like syndrome (delayed hypersensitivity) occuring seven to eight days after serum administration consist of fever, rashes, lymphaadenopathy, arthralgias. This is usually selflimiting and does not require treatment.
If the precuations mentioned above are followed, there is less likelihood of any of these reactions occuring.

E. Dosage and administration
Prior to administering the Snake Antivenin, it is obligatory to observe precautions and carry out sensitivity test as mentioned at B-3. The usual mode of administration of Snake Antivenin is either by intramuscular or intravenous route. The actual dose of Snake Antivenin, to be administered to the patient varies according to site of bite , severity of bite, age & physical status, degree of envenomation, involvement of systemic organs and time factor of initiation of treatment.

F. A suitable dosage schedule recommended is as follows
Antivenin Administration

Special note : In severly envenomated patient, initial dose of 10 to 20ml of antivenin may be administered in bolus, provided the patient is not sensitive to antivenin.

The above regimen is to be continued 3 hrs. thereafter till clotting time is less than 10 min. and the clot is firm. After completing the above regimen, 2 vials of antivenin are infused in 500ml fluid in a period of 24 hrs.
In case of viper-bite, some of the antivenin may be infiltrated around the site of bite with extreme caution.

In all cases of snake bites, antivenin is never discontinued till all the signs of envenomation disappear and clotting time is less than 10 mins.

G. Storage
Store the snake antivenin in cold between 2_oc to 8_oc it should not be allowed to freeze.

H. Presentation

                        10ml vial X box of 1
                        10ml vial X box of 5
                        10ml vial X box of 10
                        10ml vial X box of 20

L. Associated treatment including first aid
All snake bites should br treated immediately. All measures taken to meet the emergency should be quick and positive.

1. Patient should be removed to a well ventilated and quiet place. Assurance to the patient is important to overcome shock which is mainly psychogenic.

2. Ligation - If the patient presents within an hour of a snake bite, a ligature should be tied at a modearte distance above the bitten part to prevent the venom being absorbed into the uppar part of the limb. A rubber ligature is by far the best. It should be released every half an hour for about 5 to 10 seconds and then again tightened.

3. Clean the wound and apply antiseptic dressing without rubbing. Immobilise the bitten part as you would for a fracture.

4. In case of viper poisoning, small doses of benzodiazepines and / or analgesis such as paracetamol may be given for relief of pain and anxiety. In case of collapse, strychnine, pitutrin and stimulants like coramine are of special value. The use of corticosteroids is restricted to treat and minimise allergic reactions to serum. Appropriate antibiotics should be given to combat local sepsis.

5. Treatment of complications - Shock should be treated along empirical lines. Proper hydration, judicious use of frusemide, mannitol etc. is effective in preventing renal failure. Respiratory paralysis should be treated by tracheoestomy and artificial respiration. Digoxin, diuretics, sedatives, salt andfluid restrictions are indicated for treatment of cardiac failure. All patients should receive a potassium poor diet for the first 48 hours.