The dried leaflets of two varieties of Cassia, from Africa and Arabia. The active principle is cathartic acid, and there are other unimportant principles.
Senna is a simple cathartic, and acts as a stimulant to the muscular coat of the intestines, producing local reflex action, active peristalsis, and free evacuations within four or five hours. It acts especially on the colon, and does not cause constipation after its action is over. Griping pains are caused by full doses, but it is usually given in combination for the purpose of avoiding this.
Senna is excreted by the kidneys and the mammary glands. Nursing infants in this way feel its action as a laxative.
Senna is especially valuable as a laxative for children and may be given in the form of senna tea made with a teaspoonful of the senna leaves over which a teacupful of boiling water is poured and allowed to stand a short while.
This preparation tends to disorder the digestion. Dose, ʒ i.-4 Gm.
Contains six per cent. of senna with manna and sulphate of magnesium, and is an active hydragogue purgative. Dose, ℥ iv. (120 mils.)
Average dose ʒ i.-4 mils.