Agents Acting on Excretion.

Diuretics, (διουρησις, urination),—are remedies which increase the renal secretion, either by raising the general or local blood-pressure, by stimulating the secreting cells or nerves of the kidneys, or by flushing those organs, and washing them out. They are usually divided into Refrigerant, Hydragogue, and Stimulant Diuretics, according to their physiological action;—or they may be classified according to the different purposes for which they are employed. Both these classifications are fully described under the title Diuretics, at the end of the book.

Renal Depressants,—are agents which lower the activity of the renal cells, thereby lessening or suspending the urinary secretion. The drugs which act thus are Morphine, Quinine and Ergot. Instead of acting as a diuretic Digitalis may stop the secretion of urine, by so stimulating the vaso-motor centre as to greatly contract the renal vessels, and arrest the renal circulation (Brunton). This it might do if a preparation were used which was deficient in Digitoxin or Digitaleïn, the dilators of the renal arteries : (see under Digitalis) The same is true of Caffeine and Strychnine, both diuretics,—hence it is well to combine these with other diuretics which dilate the renal vessels, as the Nitrites, (Nitrous Ether, etc.), and Alcohol. Digitalis contains in itself the power of doing both these actions, and hence it is the ideal diuretic.

Urinary Alkalinizers,—when taken internally cause the urine to have an alkaline reaction. They include the Alkalies, especially salts of Potassium and Lithium, but excepting Ammonia, which is broken up in the organism, and Sodium salts, which are not so efficient as other agents, being partly excreted by the bile and the bronchial mucus, and partly locked up in the system as the neutral chloride, while the urate of sodium is insoluble.

Urinary Acidifiers,—are very few, comprising only Benzoic Acid, Salicylic Acid, and Vegetable Acids in excess;—also excess of proteids, sugar and starch, in the food, and certain wines and spirits. The Mineral Acids, being excreted as neutral sulphates, chlorides, phosphates, etc., have little or no influence on the acidity of the urine.

Vesical Tonics,—increase the tone of the muscular fibres in the wall of the bladder, and consequently the contractile power of that organ. The chief members of this class are Strychnine, Cantharis, Belladonna, and the Bromides; all of which, carried to excess, will paralyze these same fibres by over-stimulation. This is particularly true of the Bromides.

Vesical Sedatives,—lessen irritability of the bladder, decreasing the desire to micturate, and relieving vesical pain. The most important are—Opium, Belladonna, Hyoscyamus, Cannabis, Stigmata Maidis, Calcium Carbonate, Buchu, Uva Ursi, Pareira, Copaiba, and Cubeb; also Barley-water, Linseed tea, and other mucilaginous drinks.

Urinary Sedatives,—act in a sedative manner upon the whole extent of the urinary tract, through the medium of the urine, which, being charged with them, brings them into contact with the genito-urinary mucous membrane. Some of them may be applied locally as far as the urethral and vesical mucous surfaces, the portion above being inaccessible to direct local medication. Such are Potassium and Lithium Salts to lessen the acidity of the urine;—Copaiba, Cubeb and Oleum Santali as antiseptics and astringents, in cystitis and urethritis; also Eucalyptus and Corn Silk for the same purpose;—and urethral and vesical injections of solutions containing Boracic Acid, Alum, Lead and Zinc Acetates, Silver Nitrate, etc., agents which may also be applied to the urethra through the medium of gelatin pencils (Bougia) medicated with them.

Antilithics, and Lithontriptics, (αντι, against, λιθος, a stone, τριβω, I wear down),—are agents which are supposed to prevent the formation of concretions in the ducts, (antilithics), or to dissolve said concretions when formed, (lithontriptics). The efficiency of any agents, for the purposes named, is more than doubtful. Those recommended for the various concretions are as follows, viz.—

For Uric Acid Calculi—Distilled Water, Potash or Lithia, and salts of these metals, Magnesium Citroborate, Potassium Tartraborate, Piperazin.
For Phosphatic Calculi,—Benzoic Acid and the Benzoates, especially Ammonium Benzoate, Dilute Nitric Acid.
For Calcium Oxalate Calculi,—Dilute Nitro-hydrochloric Acid, Carbonic Acid Waters, Lactic Acid, for the digestive disturbance.
For Biliary Calculi,—Ether and Turpentine, (Durande's Solvent), Sodium Salts, Castile Soap, Alkaline Waters, especially Vichy.

Diluents,—are indifferent substances which, being absorbed, pass readily through the body, diluting its fluids and excretions. Water is the only true diluent, whatever form it may be disguised in, as teas, weak fluid foods, acidulated drinks, etc.

Diaphoretics and Sudorifics, (διαφορεω, I carry through; sudor, sweat, facio, I make),—increase the action of the skin, and promote the secretion of sweat, those which act most energetically being designated by the latter title.

Simple Diaphoretics,—are those which enter the circulation and stimulate the sudoriferous glands during their elimination,—as Jaborandi, Spirit of Mindererus (Liq. Ammonii Acetatis), Sweet Spirit of Nitre (Spiritus Etheris Nitrosi), Alcohol, Salicylates, Camphor, Sulphur, etc.
Nauseating Diaphoretics,—are those which act by producing relaxation and dilatation of the capillaries,—as Tartar Emetic, Ipecacuanha, Dover's Powder, Lobelia, Tobacco, Baths, Heat, etc.
Refrigerant Diaphoretics,—are such as act by reducing the force of the circulation, and perhaps also by a specific action on the sweat-centre in the medulla,—as the Potassium and Ammonium salts, Aconite, Veratrum, Cocaine, Tobacco, Jaborandi, Ether, Nitrites, etc.

Anhidrotics, (αν, without, ιδρως, sweat),—are agents which check perspiration, acting in either of three ways, the reverse of those for the diaphoretics. The most energetic member of this class is Atropine, and others are Muscarine, Ergot, Zinc Salts, Acids locally, Cold locally, Opium, etc. The latter in small doses checks perspiration, but in large doses promotes it.

A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.