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.
Bitter Wood, Picrasma excelsa; also known as Picraena excelsa. Official in the U. S. P. IX and in eleven other standards.
Quassia is a tannin-free bitter; hence it can be combined with iron. Quassin is toxic to some animals, and in man causes burning and dryness in the throat. The tincture, in 30-minim doses, is a useful bitter. For the therapeutics of the bitters, see "Gentian."
Infusions of quassia, given as enemeta, are used in the treatment of threadworm infestation, the infusion being made weak and frequently used in the case of young children. Do not use a diluted alcoholic preparation for this purpose. Ordinarily 1/2 pint of infusion (1:100 of cold water) is injected in the case of older children or adults ("seat worms") with the patient in the knee-chest position.