Page 648 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

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VetBooks.ir Chapter 47

Non-Anticoagulant Rodenticides

Ramesh C. Gupta

STRYCHNINE Background
Introduction Strychnine was first discovered in Saint-ignatii (S. ignatii)
beans in 1818 by two French scientists (Joseph-Bienaime
Strychnine is an alkaloid derived from the seeds and bark
Caventou and Pierre-Joseph Pelletier). S. ignatii is a woo-
of a tree, Strychnos nux-vomica is native to Southeast
dy climbing shrub found in the Philippines. In general,
Asia (India, West Indies, Sri Lanka, and Indonesia) and
the beans have the same properties as the species S. nux-
Australia. Strychnine is also found in Strychnos ignatii.
vomica. Strychnine is also found in other species of
It’s a white, odorless, crystalline powder that has the Strychnos (i.e., S. colubrine and S. tieute), and is accom-
chemical formula C 21 H 22 N 2 O 2 and a molecular weight of
panied by another alkaloid brucine. The ripe seeds of
334.41. Its structural formula is shown in Fig. 47.1.
Strychnos look like flattened discs, which are very hard
Nux-vomica/strychnine has been used for at least five
and covered with satiny hairs. The properties of strych-
centuries for both pests and people. Its major use is as a
nine are substantially those of the nux-vomica. Strychnine
pesticide (rodenticide, avicide, and insecticide), but it is
is an extremely toxic alkaloid primarily used to kill
also used as a therapeutic agent in human ailments (laxa-
rodents, moles, predatory animals, and birds, or used to
tive, appetizer, and central nervous system (CNS) stimu-
trap fur-bearing animals. Pharmaceutically, strychnine is
lant). In addition, strychnine in small amounts is known to
an unjustifiable component of traditional tonics, cathartic
be added to lysergic acid diethylamide (LSD), heroin,
pills, and CNS stimulants.
cocaine, and other “street drugs,” and has been known to
cause poisoning (O’Callaghan et al., 1982). Strychnine has
many names, and is sold under various trade names,
including Boomer-Rid, Certox, Dog-button, Dolco mouse Toxicokinetics
Ceral, Gopher Bait, Gopher Gitter, Kwik-kill, Stricnina,
Mole death, Mouse-nots, Mouse-rid, Mouse-tox, Ro-dex, Following ingestion, strychnine is readily absorbed in
Strychnos, and Sanaseed. Strychnine poisoning in animals the gastrointestinal (GI) tract, but mainly in the small
occurs from ingestion of baits designed for use against intestine. Soon after absorption, it readily distributes
rodents. The most common domestic animal to be affected to various tissues within 5 min (Reynolds, 1982).
Strychnine is readily metabolized in the liver. In fact, the
is the dog, either through accidental ingestion or through
metabolism is rapid enough that approximately two
intentional poisoning.
lethal doses can be given over 24 h without cumulative
effects. Its half-life has been reported to be approxi-
mately 10 h in humans. Elimination of strychnine is also
rapid, as its unchanged residue can be detected in the
urine within a few minutes of exposure. The elimination
constant (K el 5 0.07 h 21 ) indicates that 7% of the strych-
nine in the serum at any one moment would be elimi-
natedin1 h(Edmunds et al., 1986). Following exposure
to a sublethal dose of strychnine, approximately 50% of
the dose is eliminated within 6 h (Boyd et al., 1983),
10% 20% within 24 h, and almost completely in
FIGURE 47.1 Structural formula of strychnine. 48 72 h (Cooper, 1974).

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