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.
Cassia species universally official. The Alexandria, India, and Sudan senna are all more or less recognized. Senna Pods, from Cassia acutifolia, are recognized in several other countries, but not in the U. S. Cassia Pods, from Cassia fistula, is a form of cassia that was official in the U. S. P. VIII. This latter is a nauseating agent now deleted, but has enjoyed a vogue as an ingredient of the purgative confections. Cassia Marilandica, American Senna, acts similarly to other species but is less active, and doses must be one-half larger. Prairie Senna, Cassia chamaecrista, is another American species similar in action to the American senna.
Senna, rhubarb, aloes, cascara, and some minor purgatives belong to the anthracene group; they contain derivatives of anthraquinone, emodin and related compounds being found in them. This group has a mildly irritant action, acting better than the resin anhydrids in chronic constipation; the seat of action is largely in the lower intestinal tract. Unlike rhubarb, senna possesses no astringency. The principle that nauseates and gripes is removed by exhausting with alcohol, and the official products so prepared are as pleasant as any proprietary preparations.
Senna is an efficient and safe cathartic, non-irritating and not followed by constipation. Its most active preparation is the fresh infusion, which is apt to be unpleasant, in that it induces nausea and griping. Carminatives may be combined with it, as is done in making the syrup (dose, 1 fl. drachm), a most eligible and reliable preparation. The compound infusion, Black Draught, contains senna, manna, magnesium sulphate, and fennel. It is given in doses of 3 to 6 fluidounces in the morning, usually following a mercurial taken at night. It is a nasty dose, and it is inferior to the compound licorice powder, q. v. To children is given the confection of senna, N. F., the average adult dose being 60 grains.
If a nursing woman takes senna it purges the babe. The combination of senna and cascara is a good laxative for a pregnant woman. Senna is apt to aggravate hemorrhoids.
Average dose of the leaves, 60 grains; fl., 30 minims; syrup, 1 fluidrachm; confection, 60 grains. Senna enters into many formulae.
Several synthetic purgatives, such as "purgatin" and "exodin" are based on the anthraquinone nucleus, the more prominent being Phenolph-thalein, made official in the U. S. P. IX. The dose is 2 to 6 grains; average 2 1/2 grains.