Mechanism of Antivenom *

Antivenom acts to neutralize the poisonous venom of the cobra and causes the venom to be released from the receptor site. Thus, the receptor sites that were previously blocked by venom are now free to interact with the acetylcholine molecule, and normal respiration resumes. The spent antivenom and the neutralized venom are then excreted from the body.

Venom composition (and its corresponding toxicity) can vary among cobras from the same species and even from the same litter--it can also vary for an individual cobra during its lifetime--and all of this makes each cobra bite truly unique. In order to insure correct treatment, antibodies specific to each form of cobra venom must be developed. The correct antibodies may be synthesized by injecting horses with a small amount of cobra venom, and then collecting the antibodies produced by the horses' immune systems. Of course, large samples of cobra venom must be collected for this process, and many snake farms around the world make significant amounts of money by harvesting the deadly snake toxin.


Milking a cobra for venom! (Quicktime Movie - 8.8MB)

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Careful execution of the injection of the antivenom is necessary to avoid any complications that may result from improper treatment. If the amount of antivenom is not sufficient to neutralize all of the venom, a portion of the receptor sites will remain blocked and the person would require the use of artificial respiration machines and electrical impulses to have complete respiration. Due to the size of the antivenom molecule, if given in great excess it may act to shield the receptor site from interaction with the acetylcholine molecule. Thus, the victim would develop symptoms similar to that of being bitten by a snake. Unlike cobra venom; however, the antivenom will eventually be released from the body. The rate of release is very slow, and although there are no proven cases of excess antivenom causing death, severe problems such as paralysis have occurred.





* [The reader should note, that the correct technical term to use here is antivenin, not antivenom. The authors made the decision to use antivenom rather than antivenin, because this is a non-technical presentation, and the average person is more familiar with the word antivenom. It is also more intuitive to use the word antivenom, when discussing a substance that works against venom.]