This section is from the book "Materia Medica And Therapeutics - Vegetable Kingdom", by Charles D. F. Phillips. Also available from Amazon: Materia Medica And Therapeutics: Vegetable Kingdom.
Active Ingredients. - These, notwithstanding some conflicting opinions, appear to be exclusively represented by the Cathartic acid of Dragendorff and Kubly. It is an acid glucoside, amorphous, of a brown color until dried, when it becomes black; its alcoholic solution, when boiled with acids, produces sugar, and Cathartiginio acid, a yellowish brown substance, which is insoluble in water and in ether. The formula of Cathartic acid is C180H95N2O82S.
Physiological Action. - Infusion of senna, when injected into the veins, produces both vomiting and purging. Taken into the stomach in moderate or medicinal doses, it causes, first, a sensation of warmth in that part, and in the abdomen; the pulse becomes slightly accelerated, and a safe purgative action soon ensues, the stools being liquid, and of a yellow color. Even the odor of senna leaves or of the infusion is, in certain susceptible persons, sufficient to cause an evacuation of the bowels1. In large doses it produces nausea, vomiting, griping, flatulence, depression, and, after a little excitement of the pulse, severe drastic purgation, with tenesmus. Senna often also produces haemorrhoids, and in women is apt to increase the monthly discharge. If taken by nurses, the infant is generally purged, a fact which shows that the senna is absorbed, and then thrown out of the system by the excretories.
Although a drastic, the action of senna is remarkable for its mildness. Even when administered in large doses, the effects, though powerful and disagreeable, are never poisonous. Compared with rhubarb, it is more irritant and energetic, but devoid of the tonic properties which belong thereto. Compared with aloes, the action is more powerful and speedy, especially upon the small intestines; the action upon the large one is less decided. When acrid and griping effects are produced by moderate doses, the action is referable probably not so much to the senna as to the leaves of certain plants with which the drug may have been adulterated during collection.
(According to R. and V. senna is a hepatic stimulant of feeble powei-. It renders the bile more watery. - Brit. Med. Joum., Nov. 6, 1875.)
Therapeutic Action. - Senna being a safe and certain purgative, is employed with advantage whenever there is occasion for prompt evacuation of the bowels, without possibility of failure, and especially when the small intestines require emptying. In all forms of inactivity of the alimentary canal it constitutes a well-known domestic remedy. Ordinarily the infusion is combined with solution of Epsom salts, or tartrate of potash, or with manna, or tamarinds. If a more vigorous action than usual is desired, it is said to be well to combine the senna with guaiacum. In order to cover the nauseous taste, Dr. Cullen recommends the admixture of coriander seeds.
1 Stille, vol. ii, p. 447.
In cases of constipation, of worms, and of determination of blood to the head, senna is likewise resorted to with great benefit to the patient. Children and elderly persons are especially suitable subjects to derive advantage from it.
The difficulty with senna is that, should inflammation of the mucous membrane of the bowels be present, or if there is a tendency to haemorrhoids, menorrhagia, or abortion (in the case of pregnant women), it becomes hurtful, by reason of the irritation it is apt to excite. Senna should be employed with caution, also, when there is febrile disorder, the action of this drug upon the pulse being excitant. In such cases as these it is better, perhaps, not to resort to senna at all, but to supersede it with one of the saline purgatives. Again, if the large volume of senna-tea required for an efficient dose be found objectionable, the electuary called "Confectio sennas" may be recommended as a form more convenient, and to most persons less unpalatable. This latter preparation is not only very successful in its medicinal use, but by no means disagreeable, and may very wisely be prescribed for children and pregnant women, and in cases of habitual costiveness.
Senna has the additional recommendation of not leaving the bowels confined after its purgative effects have passed away. This quality renders it particularly valuable when the bowels are constantly, though not seriously, confined, and when medicine, for the sake of relief, has to be constantly resorted to.
Preparations And Dose. - Senna, 3 ss. - 3 ij. (2. - 8.); Confectio Sennae, 3 j. - ij. (4. - 8.); Ext. Sennae Fl., 3 j. - ij. (4. - 8.); Infus. Sennas,
- ij. (30. - 60.).