This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
Prepared like extract of Socotrine aloes.
Action and Uses. - It causes a bitter taste in the mouth, and reflex salivation. In small doses it seems to have a topic action like simple bitters. It increases peristalsis of the intestines and also intestinal secretion. Its action is particularly exerted on the large intestines, and especially in the rectum. This is shown by the great length of time which usually elapses between its administration and its action (ten or twelve, sometimes as much as twenty-four, hours), and by the rectal irritation which it produces, and which is evidenced by tenesmus, haemor-rhoidal swelling, and haemorrhage. It increases the secretion of bile by stimulating the liver (Rohrig and Rutherford). It only acts when mixed with bile, and is consequently useless in jaundice, where the bile does not enter the intestine, as is shown by the whiteness of the stools. It may, however, be rendered active by giving it along with ox-gall. Aloes has little or no purgative action when given alone as an enema, but is active if mixed with ox-bile. In the enema aloes, B.P., it is mixed with carbonate of potassium. Aloes appears to cause hyperemia of the uterus and other pelvic organs, as well as of the rectum. In acute and chronic poisoning by aloin, the kidneys are affected, the tubules losing their epithelium, while the glomeruli remain intact, but become surrounded by an increase of fibrous tissue. In both forms of poisoning there is albuminuria.1 Aloes sometimes has an aphrodisiac action, but this is not constant, and probably is due to irritation caused by haemorrhoids (p. 448). Aloes differs from other purgatives in not causing subsequent constipation, but on the contrary rendering the intestine more sensitive, so that the dose can be gradually reduced. As it does not cause subsequent constipation, it is a favourite purgative, and is contained in most vegetable purgative pills (except pil. scamm. co.). As it acts slowly, it should be given a good while before a motion is desired, and a favourite plan is to give it as a dinner pill just before the last meal of the day, when it usually acts next morning after breakfast. I have known people who have taken dinner pills regularly every day for thirty years without injury and with apparent benefit. As it tends to cause congestion of the rectum, some authorities prohibit its use in piles, but in small doses, and if the piles are not inflamed, it is often beneficial in these cases, although large doses are injurious. From its action in causing congestion of the uterus, it is used in amenorrhoea (at the time when the catamenia are expected), but must be avoided in pregnancy and rectal inflammation. In these cases it is usually combined with iron or myrrh.
1 A. Murset, 'Untersuch. uber Intoxicationsnephritis,' Archiv f. exp. Path. und Pharmak., Bd. xix., p. 310.