Drug Information for Wyeth Antivenin (Micrurus fulvius) (Equine Origin) North American Coral Snake Antivenin (Wyeth Pharmaceuticals Company): Dosage and Administration

  • IMPORTANT: Before administration, read sections on “CONTRAINDICATIONS, WARNINGS, PRECAUTIONS and Adverse Reactions” Since the possibility of a severe immediate reaction (anaphylaxis) always exists whenever horse serum is administered, appropriate therapeutic agents, such as tourniquet, oxygen supply, epinephrine 1:1000, and another injectable pressor amine (NOT corticosteroids), must be ready for immediate use.

    Start an intravenous drip of 250 to 500 ml of Sodium Chloride Injection, USP. If the results of appropriate tests have indicated the patient is not dangerously hypersensitive to horse serum, and depending on the nature and severity of the signs and symptoms of envenomation, administer the contents of 3 to 5 vials (30 to 50 ml) INTRAVENOUSLY by slow injection directly into the intravenous tubing or by adding to the reservoir bottle of the intravenous drip. (If added to reservoir bottle, mix by gentle swirling—DO NOT SHAKE.) In either case, the first 1 or 2 ml should be injected over a 3- to 5-minute period with careful observation of the patient for evidence of allergic reaction. If no signs or symptoms of anaphylaxis appear, continue the injection or intravenous infusion. The rate of delivery is regulated by the severity of signs and symptoms of envenomation and tolerance of Antivenin. However, until the equivalent of 30 to 50 ml of undiluted Antivenin has been given, administer at the maximum safe rate for intravenous fluids, based on body weight and general condition of the patient. For instance, if given by intravenous drip to a previously healthy adult, allow 250 or 500 ml to run in within 30 minutes; in small children, allow the first 100 ml to run in rapidly but then decrease to a rate not to exceed 4 ml per minute. Response to treatment may be rapid and dramatic. Observe the patient carefully and administer additional Antivenin intravenously as required.

    According to the data reported by Fix and Minton2 and cited above concerning venom yields obtained under artificial but probably physiological biting conditions, some envenomated patients may require administration of the contents of 10 or more vials to neutralize the venom dose injected by the biting snake if the entire venom load were delivered by the bite(s).

    Snakes' mouths do not harbor Clostridium tetani. However, appropriate tetanus prophylaxis is indicated, since tetanus spores may be carried into the fang puncture wounds by dirt present on skin at time of bite or by nonsterile first-aid procedures.

    A broad-spectrum antibiotic in adequate dosage is indicated if local tissue damage is evident.

  • Technique for Reconstituting the Dried Antivenin

  • Pry off the small metal disc in the cap over the diaphragms of the vials of Antivenin and diluent. Swab the exposed surface of the rubber diaphragms of both vials with an appropriate germicide. With a sterile 10 ml syringe and needle, withdraw the diluent (Sterile Water for Injection, USP) from the vial of diluent and insert the needle through the stopper of the vacuum-containing vial of Antivenin. The vacuum in the Antivenin vial will pull the diluent out of the syringe into the vial. However, delivery of 10 ml of diluent may not always exhaust the vacuum in the Antivenin vial. If all vacuum is not exhausted, reconstitution may be more difficult. Therefore, either disconnect the needle from the syringe and allow room air to be pulled into the Antivenin vial until all vacuum is released from the container or withdraw the syringe with attached needle from the vial, pull 10 ml of room air into the syringe and reinsert needle with attached syringe containing room air through stopper and repeat, if necessary, to release any remaining vacuum. At the first introduction of diluent into the vaccine vial, it is important for the needle to be pointed at the center of the lyophilized pellet of Antivenin so that the diluent stream will wet the pellet. If the diluent stream is not directed at the pellet but allowed to run down the inside wall of the vial, the pellet will float up and adhere to the stopper thereby rendering complete reconstitution much more difficult. Agitate by swirling, NOT by shaking, for 1 minute, at 5-minute intervals. Gentle agitation will hasten complete dissolution of the lyophilized Antivenin. Shaking causes foaming and if the diluent stream is not properly directed as described earlier, pieces of the pellet may get caught in the foam and will be very difficult to wet. Complete reconstitution usually requires at least 30 minutes.

    Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. The color of reconstituted Antivenin may vary from clear to slight yellowish or greenish.

    Before each administration, gently swirl the vial to dissolve the contents.

    Before any Antivenin is administered, an appropriate horse-serum sensitivity test must be done so that, in case administration of Antivenin is subsequently required, a decision on how to proceed will have been made (see PRECAUTIONS).

  • Drug Information Provided by National Library of Medicine (NLM).