Antivenom

Antivenom

Antivenom, also known as antivenin or antivenene, is a biological remedy employed in the treatment of bites or stings from venomous creatures. It is produced by extracting venom from the desired snake, spider, or insect, which is then diluted and injected into a horse, sheep, or goat. The animal undergoes an immune response to the venom, generating antibodies against its active components, which are subsequently harvested from the animal's blood for use in treating envenomation. Globally, antivenoms must adhere to the standards outlined by pharmacopoeia and the World Health Organization (WHO).

The concept of antivenom is akin to that of vaccines developed by Edward Jenner. However, instead of inducing immunity directly in the patient, it is generated in a host animal, and the hyperimmunized serum is transferred to the patient.

Antivenoms intended for therapeutic purposes are commonly preserved as freeze-dried ampoules, although some are available solely in liquid form and require refrigeration. While they are not immediately deactivated by heat, minor disruptions in the cold chain are not catastrophic. Most antivenoms, including those for snake bites, are administered intravenously, although stonefish and redback spider antivenoms are administered intramuscularly. The efficacy of the intramuscular route has been debated in certain situations for its lack of uniform effectiveness.

Antivenoms bind to and neutralize the venom, thereby halting further damage, but they do not reverse damage already inflicted. Therefore, they should be administered promptly after venom injection, but they still offer some benefit as long as venom remains in the body. Since the introduction of antivenoms, bites that were once fatal have become exceedingly rare fatalities, provided the antivenom is administered promptly.

Despite undergoing several purification processes, antivenoms may still contain other serum proteins that can trigger immune reactions in some individuals. Immediate hypersensitivity reactions (anaphylaxis) or delayed hypersensitivity reactions (serum sickness) may occur, necessitating cautious use of antivenom. Nonetheless, antivenom is typically the only effective treatment for life-threatening conditions, and once precautions for managing these reactions are in place, anaphylactoid reactions do not warrant withholding antivenom if otherwise indicated. Although it is often believed that individuals allergic to horses "cannot" receive antivenom, the side effects are manageable, and antivenom should be administered as quickly as possible, with side effects managed accordingly.

While individuals vary in their physiological responses and sensitivity to animal venoms, humans lack natural immunity to them. However, some ophiophagous animals, such as Kingsnakes, opossums, mongooses, and hedgehogs, are immune to the venoms of certain venomous snakes due to the presence of antihemorrhagic and antineurotoxic factors in their blood.