Cevadilla

Historically applied as a lotion or ointment for pediculosis when gentler agents had failed

Once used internally in minute, tightly controlled doses for lancinating facial neuralgia, a use no longer considered acceptable given the narrow margin of safety

Overview. Sabadilla is the dried ripe seed of a bulbous plant native to Central America and parts of South America, long known to Mexican and Central American peoples and later imported into European and North American commerce chiefly as a source of veratrine alkaloids used in insecticides and pediculicides. Eclectic and early physiomedical practitioners occasionally used tinctures of the seed internally in extremely small doses for severe neuralgic pain, but this internal use has been abandoned because of the plant's narrow margin between an active dose and a dangerous one. Today sabadilla survives mainly as a historical curiosity and as a topical parasiticide in some traditional and veterinary preparations.

Clinical Notes. Sabadilla seed contains a mixture of veratrine-type steroidal alkaloids, principally cevadine and veratridine, that act on voltage-gated sodium channels to prolong their open state. This produces intense local irritation on mucous membranes and, if absorbed systemically, can cause profound bradycardia, hypotension, muscle weakness, and respiratory compromise.