As the junior student will be frequently meeting in the portion of this work under the heading "Materia Medica" with words whose meaning he cannot understand, the following brief glossary is inserted here, not as an attempt to classify remedies, but merely for facility of reference, in order to explain terms in constant use which apply to many groups of well-known remedies.
A complete therapeutical classification of drugs is not yet possible. The attempts of Buchheim and Schmiedeberg are in many details unsatisfactory and sometimes misleading.
There are two well-recognised and often-mentioned effects of a remedy - the physiological or pharmacological and the therapeutical - and the student should be familiar with both these terms. By the physiological action of a medicine is generally meant the effects which the medicine will produce when administered to a person in health though it should he remembered that to produce these effects a perfectly healthy state is not necessary. Thus, if 10 or 20 grains of quinine be administered to a perfectly healthy subject, the constitutional effect of the remedy soon shows itself in the characteristic group of symptoms called cinchonism. This is spoken of as the physiological or pharmacological action of quinine. If an ordinary medicinal dose of this drug be administered to a patient ill with the ague or neuralgia, it will be found to remove the disease; this is the therapeutical effect of the remedy. Suppose, however, the dose be a very large one, as in the first instance, the remedy may produce cinchonism, even though the patient have ague or neuralgia, and in this case the effects would still be called physiological. It will thus be understood that, in administering a remedy in disease, the physician often desires it to be given in such a quantity that the physiological effects of the drug should be made evident, as in treating syphilis with mercury, chorea with arsenic, paralysis with strychnine, or pertussis with belladonna.
How most drugs exercise their peculiar selective power over particular tissues and organs is a very difficult question, but the trend of opinion is certainly in the direction of regarding all such actions as being purely chemical. The general relationship between chemical constitution and pharmacological action first made manifest by the researches of Crum Brown and Fraser, strongly supports the chemic theory. These observers found that by altering slightly the structure of the strychnine molecule by the introduction of the radical methyl, its convulsing was changed into a paralysing action.
The researches of Ehrlich in his discovery of salvarsan have established the theory that many drugs suffer a chemical change when carried by the blood to the tissue or parasitic organism upon which they act. A group of atoms in the complex molecule of the protoplasm enters into combination with a corresponding radical group in the drug. This union being the determining factor in the therapeutic action of the remedial agent. Hence the meaning of the new term chemotherapy as applied to specific drug treatment. Sir Almoth Wright goes a step farther, insisting that in serum and vaccine therapy the attack on the microbe is always a chemical attack. (See in the article on Antitoxins a description of the side chain hypothesis of Ehrlich.)
There are several terms constantly employed in the description of the actions of drugs which are unfortunately used in different senses by different writers. The local or direct action of a drug is seen in the case of swallowing a corrosive poison which injures the mucous lining of the stomach. Its remote or indirect action would be seen in the stoppage of the heart which might result from its secondary influence upon the nerves and circulation. The primary or immediate action of a dose of croton oil would be to clear out the intestinal canal, its secondary or remote action might he to remove dropsical effusion in the brain or cellular tissue, or to relieve uraemia.
Absorbents are drugs like wood charcoal, which are used for causing absorption of irritating secretions on the surface of the body, or of gaseous products in the digestive tract.
Acids. - Though these are always regarded as a group of remedies belonging to a chemical classification, the additions to our knowledge of the effects of acid substances justify the mention of them as a group in a therapeutical list. They are medicines which, in the concentrated form, act mostly as caustics, and when given in medicinal doses possess the power of checking the acid secretions of the body with which they come in contact, and, at the same time, they directly increase alkaline secretions. It is by this theory that Ringer explains their use in acid dyspepsia, sweating, etc. The principal members of the group are hydrochloric, acetic, nitric, sulphuric, phosphoric, nitro-hydrochloric, and citric acids.
Alkalies or Antacids. - Under this head are included substances which have the power of checking alkaline and stimulating or increasing acid secretions. The most important are caustic soda and potash, with their carbonates, bicarbonates, acetates, and citrates; ammonia and magnesia, with their preparations. Of this class, there are those which act directly as soda does upon the gastric membrane, and those which also act indirectly through the blood.
Alteratives are a class of remedies which, when administered in the ordinary medicinal dosages, cure disease without producing any obvious impression on any of the organs of the body; and because the way in which they act is not understood, or capable of demonstration, in the present state of our ignorance, they are said to alter the morbid processes, and hence are called "Alteratives." The most important of this class are antimony, mercury, arsenic, iodine, colchicum, and their preparations. They may be regarded as the survivors of the old empiric class of "Specifics," though they still remain amongst the most valuable of our therapeutic agents.
Anaphrodisiacs are medicines which weaken the sexual functions, as camphor, bromides of ammonium and potassium, tobacco, hemlock, iodides of sodium and potassium.
Anaesthetics are medicines which produce loss of sensation and consciousness from their effects upon the brain and spinal centres. The term is usually restricted to volatile substances like chloroform, ether, methylene, nitrous oxide gas, etc., and does not include narcotics like alcohol and opium, which like-wise produce anaesthesia.
Anaesthetics (Local) are agents which, when applied directly to a part, destroy its sensibility by their action on the sensory nerves, without injuring the tissues - as ether in the form of spray, cocaine, carbolic acid, ice, veratrine, etc.
Analgesics or Anodynes are remedies which relieve pain by their action on the brain, or their influence over the conductivity of the sensory nerve fibre, as opium, Indian hemp, belladonna, aconite, chloroform, antifebrin, antipyrine, etc.
Anhidrotics are medicines which restrain profuse perspiration. They act by (1) paralysing the terminals of the nerves going to the sweat glands, or (2) by their influence upon the gland cells, or (3) upon the sweat centres, or (4) upon the circulation, as belladonna, atropine, hyoscyamus, stramonium, muscarine, quinine, zinc salts, the vegetable and mineral astringents, and picrotoxin in small doses.
Antacids. (See Alkalies.)
Anthelmintics, Vermifuges, Vermicides, or Antiscolics are medicines which destroy or cause the expulsion of worms, as atropine for the round worm, kousso, kamala, male-fern, turpentine, areca nut, and pomegranate for the tape and broad worms, injections of salt, tannin, quassia, alum, iron, lime-water, etc., for the thread worm, and thymol for the ankylostoma parasite.
Antagonists are medicines which act in direct opposition to each other, as atropine and muscarine; atropine and hydrocyanic acid ; atropine and physostigmine ; atropine and pilocarpine ; digitalin and saponins; chloral and strychnine; opium and belladonna; alcohol and strychnine.
Antidotes are medicines that relieve or remove the symptoms caused by poisons. Antidotes are chemical, as lime for sulphuric acid ; physiological, as strychnine for woorara ; or vital. as mercury for syphilis.
Antilithics or Lithontriptics are medicines supposed to possess the power of dissolving various concretions in the body, as the acids for phosphatic, and the alkalies for uric acid calculi and Castile soap and salicylate of soda for gall-stones.
Antiparasitics are medicines which destroy minute parasitic organisms, as sulphurous and carbolic acids, iodide of sulphur, and various mercurial salts, and time innumerable list of antiseptics.
Antiperiodics are medicines which antagonise the poison of periodic disorders like ague. The principal members of the group are quinine, arsenic, and iodine.
Antiphlogistics are remedies which are supposed to possess the power of subduing inflammations - as mercury, aconite, veratrum viride, purgatives, antimony, venesection, etc.
Antiseptics are medicines which prevent putrefaction by arresting the growth and development of the germs, upon whose presence infection depends. Boracic acid may be taken as the type of this class. They should not be confounded with Disinfectants like hot air or phenol, which destroy the germs causing disease, or with Deodorants like chlorine or charcoal, which destroy fetid smells and emanations. Some of the newer antiseptics, as urotropin, act on time renal secretion after being eliminated by the kidney from the blood.
Antisialics are remedies used to diminish or check the secretions of the salivary glands, as atropine, and physostigma in large doses.
Antipyretics are remedies which reduce the temperature in fevers and diseased conditions. They do so either (1) by lessening thermogenesis or heat production through their effect on the nervous system, as antipyrine, antifebrin, quinine, salicin, etc., or (2) by destroying the poison which causes the fever, as arsenic and iodine in ague, or (3) by increasing heat dissipation through their action on the skin or circulation, as alcohol, antimony, aconite, etc., or (4) they may act by heat abstraction, as the cold bath amid large doses of diaphoretics and sudorifics do.
Antispasmodics. Several distinct groups of remedies are included under
(1) Medicines which paralyse the motor centres or nerves, as Calabar bean, chloroform, and woorara, or which merely depress them, as bromides of potassium and ammonium.
(2) Medicines which produce profound general depression of all the vital functions, as tobacco, aconite, lobelia, hellebore, prussic acid; and many remedies called sedatives.
(3) Medicines which, by stimulating the bowel, cause the expulsion of gas and relieve colic, as asafetida, cajuput, castor, valerian, and a host of remedies called Carminatives and Aromatics.
(4) Medicines which overcome spasm of the bronchial tubes, as stramonium, belladonna, hyoscyamus, etc.
Aphrodisiacs are medicines which increase the sexual appetite and excite the functions of the genital organs, as phosphorus, cantharides, strychnine, damiana, cannabis indica, etc. They act directly upon the genital nerve centres in the cord and brain, as strychnine, or indirectly by irritating the bladder and urethra, as cantharides.
Astringents are remedies which cause contraction of muscular fibre, and condensation of the tissues, mostly by precipitation of gelatin and albumin. The most important are tannic and gallic acids, and all substances containing them, the mineral acids and most metallic salts, alum, creosote, etc.
Carminatives. (See Antispasmodics.)
Cathartics, Aperients, Evacuants, or Purgatives are medicines which
increase or quicken the evacuations from the bowel. They are variously subdivided
(a) Laxatives, which slightly quicken the peristaltic movements, and cause only softened motions, as manna, sulphur, figs, prunes, olive oil, etc.
(b) Purgatives proper or simple purgatives, which, by increasing the movements of the intestines, and mildly stimulating the glands, cause semi-fluid motions, as senna, castor oil, mercurials, aloes, etc.
(c) Drastics, which act like the former class, only more intensely, and by their local irritant action increase the intestinal fluid, and remove the serum from the intestinal vessels, causing painful fluid motions -- as scammony, jalap, colocynth, gamboge, podophyllin, and large doses of class (b).
(d) Hydragogues, which cause free secretion from time intestinal glands, and remove much serum from the blood vessels, producing fluid or watery motions, as croton oil, elaterin, and many of the remedies in class (c) ; and large doses of various salts, like cream of tartar, Epsom, Glauber, etc., which are often called saline purgatives, and which are supposed to act by virtue of their low diffusive powers.
(e) Cholagogue Purgatives are remedies which are supposed to purge by stimulating the liver and increasing the bile, or by concentrating their action upon the duodenum they cause the bile to he swept out of the body before it has time to be reabsorbed by the intestinal surface (calomel and podophyllin) they produce greenish liquid motions ; most brisk purgatives are included in this class by writers, as aloes, iridin, mercurials rhubarb, euonymin, etc.
Vegetable cathartics are classified upon a chemical basis by Cushny:
(i) Anthracene Purgatives. - These all contain principles which are derivatives of anthraquinone.
(2) Purgative Oils, as represented by croton oil and castor oil.
(3) The Jalap Group, which are all resinous bodies, as jalap, Scammony, gamboge, podophyllin, and colocynth.
Cholagogues. The term is sometimes used to include such mild hepatic stimulants as the dilute nitro-hydrochloric acid, soda salts, and the chloride of ammonium. It should not be confounded with the class of cholagogue purgatives, many of which are true cholagogues when used in doses too small to cause any purgative action.
Ciliary Excitants are medicines which, when sucked in the mouth, promote expectoration of bronchial mucus by reflex action - as chloride of ammonium, chlorate of potassium, gum acacia, native chloride of sodium, etc.
Counter-Irritants. - Under this heading are included - RUBEFACIENTS, remedies which cause redness of the skin ; EPISPASTICS, or VESICANTS, which produce inflammation. ending in the formation of a blister: REVULSIVES and DERIVATIVES - remedies which are supposed to remove the diseased action from the seat of mischief to the place of their application. Amongst this class are cantharides, turpentine, ammonia, camphor, mustard, most volatile oils, mezereon, capsicum, croton oil, etc.
Demulcents are medicines which protect the parts with which they come in contact, by their oleaginous or mucilaginous qualities, shielding them from irritating secretions. Linseed, olive, and almond oils, starch, glycerine, liquorice, etc., are included under this head.
Diaphoretics are medicines which increase the cutaneous secretion, either by stimulating the terminal nerves in the cells of the sweat glands, as pilocarpine does, or by causing the dilatation of the superficial capillaries, as antimony, ipecacuanha, and all depressing remedies; or by stimulating the sweat centres in the spinal cord, as the spirit of nitrous ether.
Delirifacients are drugs which produce delirium, followed afterwards by stupor, as cannabis, belladonna, and hyoscyamus.
Diluents are remedies like water and weak fluid foods, which, when taken in quantity, on being eliminated, carry out some solids with them by the kidneys, lungs, or skin.
Digestants or Digestives are agents used to assist the stomach and intestines in their normal functions of digestion of foods. They are papain, pepsin, trypsin, taka-diastase, and malt extract.
Disinfectants and Deodorants are referred to under Antiseptics.
Diuretics are remedies which increase the renal secretion. Stimulating diuretics act by stimulating the kidneys during their elimination, as copaiba, cubebs, turpentine, pepper, gin, alcoholic liquors, buchu, cantharides, juniper, etc. Hydragogue diuretics act by raising the blood pressure in the glomeruli, as digitalis, squill, casca, broom, caffeine, etc. Refrigerant diuretics act by washing out the kidneys, as large doses of diluents, like water, and solutions of the various potash salts.
Ecbolics are medicines which cause contraction of the uterine muscular fibre, as ergot, borax, savin, quinine, etc.; in smaller doses they are emmenagogue.
Emetics are medicines which cause the evacuation of the contents of the stomach. They are divided into (1) Local Emetics as zinc and copper sulphates, mustard, carbonate of ammonia, tepid chamomile infusion, and solution of common salt, alum, etc., which act locally by directly irritating the nerves distributed to the gastric mucous membrane. (2) General Emetics, which act through the blood upon the vomiting centre, as tartar emetic, ipecacuanha, senega, squill, and apomorphine. Most of these latter drugs are eliminated by the gastric mucous membrane after absorption, and then also act partly as local emetics. Apomorphine may, however, be regarded as a pure general emetic.
Emmenagogues are medicines which, by their stimulating action on the uterus, (1) directly assist in restoring disordered menstruation, as ergot, savin, and most ecbolics or (2) by removing the cause of the suppression, allow the discharge to return, as iron, aloes, strychnine, etc.
Emollients or Protectives are external Demulcents, which protect and soothe the parts to which they are applied from all sources of irritation ; or, by their oily nature, they help to relax and soften the tissues, as poultices, oils, lard, spermaceti, hot fomentations, chalk, starch, etc.
Errhines are medicines which increase the secretion of the nasal mucous membrane generally without causing sneezing, as the vapour of ammonia, acetic acid, etc. The term is, however, often applied also to sternutatories.
Escharotics or Caustics are substances which destroy the life of the tissue to which they are applied, generally by depriving it of its moisture - as the strong mineral acids, soda, potash lime, arsenic, chloride of zinc, etc.
Expectorants are medicines which assist the expulsion of the bronchial
(1) By relieving spasm of the bronchial tubes, as lobelia, stramonium, tobacco, etc.
(2) By mechanically dislodging it in the act of vomiting, at the same time thinning the secretion, as all emetics in large doses, notably antimony, hippo, etc.
(3) By increasing the flow from the inflamed membrane, through their effects upon its gland cells, as all the emetic class in small doses - Nauseating or Depressant expectorants - as apomorphine, pilocarpine, emetine, and tartar emetic.
(4) By stimulating the membrane in the act of their elimination, they so alter the secretion that expectoration is rendered easy, as ammonia, senega, ammoniacum, and a host of volatile substances, notably the onion, tar, turpentine, balsams, asafetida, etc - Stimulating expectorants. Iodide of potassium, by liquefying the secretion, is a valuable expectorant.
(5) By soothing the irritable respiratory centre, morphine and chloral may act as expectorants, and render the expulsion painless, but this effect should never be counted upon, since these sedatives depress the respiratory centre and prevent coughing; they should be regarded as agents for the relief of unnecessary cough, but not as true expectorants.
(6) By acting through the impression produced on the nerves of the mouth, many substances aid expectoration. (See Ciliary excitants.)
(7) By stimulating the respiratory centre, and strengthening the muscles of the expulsive mechanism, strychnine and atropine may act as true expectorants.
Galactagogues are medicines which increase the secretion of the mammary glands, as chlorate of potassium, fennel, etc.
Haematics or Haematinics are medicines which enrich the blood by acting as restoratives to the red corpuscles, as iron and its preparations, manganese, cod liver oil, free phosphorus and lime phosphates, and potassium in small doses. They are also termed Blood Tonics.
Haemostatics are drugs which check haemorrhage after they have been absorbed and circulate in the blood. Adrenalin - the active principle of suprarenal gland - gelatin and chloride of calcium are the best examples. Ergot, tannin, turpentine and lead salts were supposed to act in the same way.
Hypnotics or Soporifics are medicines which induce sleep without causing any previous cerebral excitement. Sulphonal, trional, chloral, paraldehyde, urethane, and the new sleep producers belong to this class.
Mydriatics are remedies which cause dilatation of the pupil, paralysis of the ciliary muscle and temporary loss of accommodation, as atropine, duboisine, belladonna, homatropine, daturine, etc.; they are generally used for their local action.
Myotics are remedies which cause contraction of the pupil and diminution of ocular tension, as eserine, Calabar bean, pilocarpine, etc.
Narcotics are medicines which produce sleep by their action upon the cerebrum. They are to be distinguished by their initial exciting stage front pure Hypnotics, like trional and bromide of potassium, etc.; amongst them are opium, morphine, chloroform, Indian hemp, alcohol, and ether.
Nervines are agents which act upon the nervous system. The term includes narcotics, anaesthetics, hypnotics, excitomotors, etc.
Oxytocics are medicines employed to increase the activity of the uterine contractions during or immediately after labour, as quinine, ergot, and hydrastis.
Refrigerants are medicines which reduce the temperature of the body in fever ; the term, however, is generally applied to a class of remedies which appear to allay thirst by stimulating the mucous glands in the mouth and pharynx, as the vegetable acids, some mineral acids (much diluted), and many diaphoretics. (See Antipyretics.)
Resolvents or Discutients are medicines which are supposed to cause the absorption of inflammatory or other swellings. They appear to act by stimulating the lymphatics, as iodine, ammoniacum, etc.
Restoratives are medicines which exist already in the healthy blood or tissues, and are given in diseases where the system is supposed to be deficient in them, as iron, potash, phosphorus, chloride of sodium, etc. They are identical with Haematinics (which see).
Rubefacients. (See Counter-irritants.)
Sedatives or Depressants are medicines which depress the action of the (1) nerve centres, as tobacco, lobelia, bromide of potassium, etc.; (2) the circulatory system, as aconite, veratrum, tartar emetic, prussic acid, etc.; (3) the spinal cord, as Calabar bean, etc.
Sialagogues are medicines which increase the secretion of the salivary glands, either by a local irritation of the mouth, causing reflex activity of the glands, as pellitory, mezereon, tobacco, mustard, capsicum, etc.; or by exciting the glands during their elimination, as pilocarpine, muscarine, all the preparations of mercury, iodide of potassium, etc.
Sternutatories are substances which, by their local irritating action on the nasal mucous membrane, cause sneezing, as tobacco, hellebore, ginger, capsicum, and ipecacuanha, in powder.
Stimulants*. Under this head may be included a great number of remedial agents. The subdivisions are vague and misleading; thus there are medicines which excite the spinal cord, as strychnine, phosphorus, etc.; such are called spinal stimulants; others exalt the functions of the liver, as cholagogues; others the intestines, as calomel, Epsom salt, etc.; others the circulatory system, as digitalis, belladonna, etc.; others the stomach, as carminatives, and spices, etc.; others the skin. These latter are called external stimulants, and include all the Counter-irritants.
Stomachics are medicines which increase the vascularity of the stomach, promote digestion, and increase the appetite, as the carminative group, all the bitter tonics, arsenic, and aloes, in small doses, etc.
Styptics are medicines which arrest bleeding by their local astringent action, either by causing coagulation of the blood, or by acting on the muscular tissue of the small vessels. Amongst this class will be found suprarenal gland substance, tannic acid, creosote, alum, chloride of zinc, perchloride of iron, etc.
Sudorifics. (See (Diaphoretics.)
Tonics are, strictly speaking, medicines which improve the tone of the part upon which they act ; thus it may be on the stomach, as the pure vegetable bitters and all stomachics; or on the cord, as strychnine ; or on the heart, as digitalis ; or on the nervous system, as quinine and the valerianates ; or on the circulating fluid, as iron.
Vermicides and Vermifuges, (See under Anthelmintics.)
The term "vermicide" is sometimes restricted to a drug which causes the death of the worm, while "vermifuges" is applied sometimes to any drug which causes the expulsion of the worm; though it may not have power to cause its death.
Vesicants. (See Counter-irritants.)
*The term "Stimulant" is frequently erroneously used as a synonym for alcohol and its preparations, which should he regarded as true narcotics.
I would like to thank Dr. Alun Davies for lending me his copy of Whitla's book.