Red squill (Urginea maritima) is a large onionlike plant that
grows in coastal regions along the Mediterranean Sea and in the
United States; it contains a variety of cardiac glycosides,
including scilliroside. All parts of the plant contain scilliroside
but it is most concentrated in the bulb. There is also a white
squill whose bulbs are white. Red squill has long been known
and used medicinally. The earliest reference to red squill is in
the Ebers Papyrus as treatment for dropsy (heart failure). Use as
treatment for cough, arthritis, general diuretic, and emetic has
also been described. Medicinal use declined during the nineteenth
century because foxglove (digitalis) was revealed to be
safer and more efficacious in the treatment of heart failure.
However, use of red squill as a folk medicinal remedy
continues, and deaths and serious illness may occur. Red squill
is one of the oldest rodenticides and has been in use since the
thirteenth century. However, scilliroside has extremely poor
palatability, and many rats learn to avoid the bait. Since 1989,
rodenticides containing red squill are not approved for use in
the United States.
Rat poisonings containing scilliroside continue to be available
and used worldwide. Technical-grade red squill powders can
contain up to 28% scilliroside, and baits typically contain
0.01–0.07% of the toxicant.
Red squill has a multitude of toxic effects. It is directly irritating
to the gastric mucosa, contributing to nausea, vomiting,
abdominal pain, diarrhea, and anorexia. Rats are not able to
vomit, contributing to the perceived selectivity of toxicity in
rats. Scilliroside and scillaren A are both cardiac glycosides,
and, like digoxin, inhibit Na+/K+ ATPase, block AV conduction,
and may cause a slowed or rapid heart rate and abnormal
heart rhythms.
