This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
The action of these is obscure, but it seems certain that they very greatly increase the secretion of intestinal fluid, and hinder its reabsorption, so that a large amount of it accumulates in the intestine. The distension due to this accumulation excites gentle peristalsis, and consequently an easy, painless evacuation of the bowels. Secretion goes on till the fluid in the intestine has become a 5 or 6 per cent. solu-tion of the drug, so that if a very concentrated solution is given, much intestinal fluid is secreted. There is some doubt whether osmosis plays any part in the process. The action is entirely local, for no purgation follows if the salts are injected into the blood. Magnesium sulphate, administered hypodermatically, purges. It is possible that other salines may act similarly. The saline purgatives are -
(1) Potassium and sodium tartrate.
(2) Potassium bitartrate.
(3) Potassium sulphate.
(4) Sodium sulphate.
(5) Sodium tartrate.
(6) Sodium citro-tartrate.
(7) Sodium phosphate.
(8) Magnesium sulphate and other salts.
These are very largely used as habitual purgatives, especially for persons suffering from any form of gout. They form the essential ingredient of most purgative mineral waters, as Hunyadi Janos, Apenta, Pullna, Friedrichshall, AEsculap, Rubinat, Villacabras, etc. The best way of taking them is to put the required dose of the salt, or the mineral water, in a tumbler, add some hot water, and sip it slowly while dressing in the morning.
Cholagogue purgatives will be described when speaking of the liver.
Any fluid preparation, injected into the rectum, is called an enema. When a purgative is liable to produce sickness, or it is inadvisable, because of peritonitis, intestinal obstruction, ulceration, or other diseases, to give it by the mouth, it may be given by the rectum. Castor oil, aloes, olive oil, magnesium sulphate, soap, etc., may be administered in this way. Enough of a vehicle must always be used to make a purgative enema up to three-quarters of a pint or a pint 350. or 500. c.c., for distension of the rectum greatly aids purgation. A teaspoonful 4 c.c. of glycerin injected into the rectum, or the same amount given as a suppository, often unlocks the bowels.
These are believed to check fermentation and putrefaction in the intestines and are -
(2) Bismuth Naphtolate.
(4) Bismuth Salicylate.
(8) Corrosive Mercuric Chlo-' ride(9) Oil of Turpentine. (10) Silver Nitrate.
Naphtol has been shown to destroy micro-organism in situ. Bismuth naphtolate has not the irritating properties of naphtol, but appears to be equally effective. When pure, naphtalin is not absorbed, it does not cause toxic symptoms, nor is there any change in the urine. Salol, a combination of salicylic and carbolic acids, decomposes only in an alkaline solution, and this is useful for action in the small intestine. Chlorine water has been used for the disinfection of the intestine in typhoid fever. Creosote is valuable if administered in the form of enteric pills, which are soluble only in the intestinal fluids. Corrosive mercuric chloride is too poisonous for use, save in exceptional cases. The late George B. Wood, of Philadelphia, achieved brilliant success with oil of turpentine in the treatment of typhoid fever. Silver nitrate has a limited use as an antiseptic, in its local application to dysenteric ulcerations within reach in the rectum and sigmoid flexure. The intelligent use of the foregoing drugs has greatly improved the success of the treatment of enteritis, diarrhoea, colitis, dysentery and typhoid fever.