This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Santonin, obtained from Artemisia pauciflora, Levant Wormseed, also called Artemisia cina. Cina is the name given to wormseed in homeopathic literature. Santonin is quite generally official, and wormseed in many standards. See "Artemisia."
Absorption of santonin is principally from the intestine; if it is absorbed from the stomach toxic symptoms are produced - aggravated disturbances of color vision. More or less disturbance always follows full dosage, objects appearing with a blue tinge at first and succeeded by yellow. This action is probably due to an influence on the retina or the visual center. Large doses act as a cerebral excitant and the respiratory center is depressed.
Santonin expels the round worm, ascaris, and, somewhat less effectively, the threadworm, oxyuris; it is ineffective against tapeworm. The worms are not killed within the body, but are "stunned" and are readily swept out by a purgative. In order to mask the visual disturbance, the drug is given in the evening; it should be preceded by a light diet and a laxative, and should be followed, after a few hours, by a brisk purge; or, the common plan, calomel is given with the drug. The dose may be repeated each evening for two or three days if no disagreeable symptoms are induced.
In the case of threadworms, the eggs are liable to be found at the anus. Mercurial ointment should be used to kill them.
Be careful in administering santonin to young children: two grains has been fatal. If dangerous symptoms appear, empty the stomach and bowels. If convulsions appear, an anesthetic may be demanded.
The average dose is 1 grain. Troches usually contain 1/2 grain. Be sure they are of comparatively recent make or they may not dissolve in the intestine.