antivenom

Antivenom, also called antivenin, is a biological product used to treat envenomation by neutralizing venom toxins. It consists of antibodies derived from the plasma of immunized animals, typically horses or sheep, or from newer monoclonal antibodies. Most antivenoms are polyclonal and target multiple toxins within a venom; some newer products are monospecific.

Production involves immunizing donor animals with venom or venom components, collecting serum, and purifying immunoglobulins while removing harmful substances. Some products are processed into Fab fragments or F(ab')2 to reduce the risk of adverse reactions. Recombinant or humanized antibodies are being explored to improve safety and accessibility.

Antivenoms act by binding venom toxins, neutralizing their enzymatic activity and preventing further tissue injury. After administration, antibodies distribute systemically and are most effective when given promptly after envenomation.

Indications and administration: Antivenoms are indicated for clinically significant envenomation by snakes, scorpions, spiders, and certain marine animals. Dosing and duration depend on the venom, severity, patient age, and response, and therapy is delivered in a hospital setting by intravenous infusion. Repeated doses may be necessary.

Safety and limitations: Adverse reactions range from mild hypersensitivity to anaphylaxis and serum sickness. Access can be limited by cross-reactivity, storage requirements, and cost. Antivenoms do not reverse all venom effects, particularly established local tissue damage, and may be less effective if administration is delayed or venom has acted intracellularly.

History and current status: Antivenoms have been the main specific therapy for envenomation since the late 19th century, and ongoing research seeks to improve safety, spectrum of coverage, and global accessibility, including the development of region-specific polyclonal products and new monoclonal or recombinant approaches.