PRINCIPLES OF TOXICOLOGY

430 PROPERTIES AND EFFECTS OF NATURAL TOXINS AND VENOMS
Some sponges, such as the Caribbean fire sponge (Tedania ignis) and the nolitangere sponge
(French for do not touch!), cause chronic contact dermatitis in addition to a more immediate
inflammatory action; the active constituents of these sponges have not yet been identified.
Certain marine worms are quite poisonous. These include several species of segmented worms,
belonging to the phylum Annelida. The toxin of a species occurring in Japanese waters, nereistoxin,
has become an agriculturally useful insecticide because it blocks nicotinic cholinergic receptors. Bristle
worms commonly found in coral reefs cause quite an irritating sting, which is probably due to release
of inflammatory substances in addition to the bothersome irritation caused by the fine bristles lodged
in the skin. Another stinging annelid, used as fishing bait in the New England area, is the blood worm
Glycera dibranchiata. The proboscis “fangs” of this rather large worm inject a protein toxin that
stimulates neurotransmitter release from nerve terminals and also commonly causes some tissue
necrosis.
17.8 TOXIN AND VENOM THERAPY
Identification of the Toxic Organism
Since the toxins of closely related species often have a different chemical structure and even mechanism
of action, it is usually imperative to identify the toxic organism in order to select the appropriate therapy.
An immunologic method for identifying the species involved in a snake bite is now available in
Australia. Such kits are likely to become available in other parts of the world.
Several excellent guides for the identification of poisonous plants and animals of North America
are available to readers wishing to learn about their identification. Many food-related intoxications
result when persons sample natural or ornamental plants without proper identification, consuming the
wrong plant, sometimes with tragic consequences.
Immediate Therapeutic Procedures to Counteract Ingestion of Poisons
A highly effective initial response to the ingestion of a poisonous substance or plant is to induce
vomiting with ipecac syrup, a mixture of plant alkaloids called emetines. It is only to be used relatively
soon after poison ingestion has occurred. Under certain conditions when the patient is extremely
drowsy or unconscious it should not be used, since failure to vomit (usually 15–30 min later) might
lead to additional difficulties due to the emetine alkaloids. If the patient fails to vomit within a
reasonable period of time an additional dose is swallowed to finally cause vomiting and removal of
unabsorbed poisons.
If vomiting is unsuccessful or incomplete, gastric lavage may be carried out by trained medical
personnel; this involves placing a tube in the stomach and applying suction to remove the harmful
contents and is usually done after the patient has been sedated. After this procedure the patient is often
administered an oral dose of activated charcoal, which is effective in sequestering many poisons from
the gastrointestinal tract and is ultimately eliminated in the feces. A cathartic saline solution is often
administered to speed up elimination of the poisonous substance, charcoal adsorbed or not, from the
intestines.
This description is only meant to inform the reader of treatment options. A medical person trained
to treat intoxications should be contacted immediately for assistance of the patient!
Prospects for Improved Immunotherapy of Venoms and Toxins
Polyvalent antivenins are commonly used to treat bites from related species of snakes, since they are
often difficult to distinguish from each other. The polyvalent serum used to treat crotalid bites is
prepared by immunizing horses with a mixture of several Crotalus species; it has been shown to be
effective in the treatment of bites caused by over 65 crotalid species.