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"In the first place the remedy is to be tried on the healthy body, without any foreign substance mixed with it; having been examined as to its odor and taste, a small dose is to be taken, and the attention directed to all effects which thereupon occur; such as upon the pulse, the temperature, the respiration, the excretions. Having thereby adduced their obvious phenomena in health, you may pass on to experiment upon the sick body."
Forty or more years after these rules were laid down ex cathedra by Haller, the central idea contained in them was incorporated as one of the main pillars, into a medical edifice then being erected in Germany. In the course of construction this pillar became so hidden beneath a superstructure of palpable absurdities, that the medical profession, in its anxiety to steer clear of the whole mass, almost forgot the corner-stone of truth, appropriated from the teachings of one of its own greatest teachers. While, however, the masses of the profession, blinded by prejudice, turned away from everything which savored of drug-experiment, a few in every country were quietly working on the lines of Haller's dogma that Drugproving is the only true basis of Drug-using. As a result of their labor, the present generation sees the development of an idea, announced 130 years ago, but now inspiring the minds of teachers and students all over the civilized world. Medical Colleges are recognizing physiological drug-experimentation as a part of their regular curricula ;—laboratories are fitted up in many of the schools with costly instruments of precision, for the more exact prosecution of this study; and under the direction of such men as Wood, Ringer, Murrell, Brunton, Hildebrandt, Liebermeister, Husemann, Schmiedeberg, etc., systematic researches are being conducted upon animals to ascertain the physiological action of every agent hitherto used in medicine. The alkaloids, and other component principles of vegetable drugs, are being subjected to the same rigid observation, as also every new compound which chemistry gives to medicine. Journals, in every civilized country, teem with the results of these labors; and no medical student is permitted to pass the graduating ordeal until he has mastered the essential characteristics of the physiological action of the important medicaments so far as established. What has hitherto been the conviction of but a few, is daily growing into a fixed canon of professional belief, that physiological experimentation with drugs must be the basis of their therapeutical employment, and that all real advance towards the establishment of Therapeutics as a science, must be made upon the lines laid down by Haller, i.e., drug-proving upon the healthy human organism. Still, in the words of Brown-Séquard, "Therapeutics will cease to be empirical, only when this last kind of knowledge shall be fully obtained;"—but its fulness will never be fully realized, unless the results have been thoroughly considered with full regard to the differences due to the action of drugs in different doses on the human organism in health and disease. [Compare pages 53, 54, infra.]
ADMINISTRATION OF MEDICINES.
Medicines may be introduced into the circulation by various routes, as the gastro-intestinal tract, the rectum, the respiratory tract, the veins and arteries, the subcutaneous cellular tissue, and the integument itself.
The Gastro-intestinal Route is the one most frequently employed, being the most convenient. The remedies, after being swallowed, find their way into the current of the circulation, through the walls of the gastro-intestinal blood-vessels and the lacteals. When the stomach is empty and its mucous membrane healthy, crystalloidal substances in solution pass through the walls of its vessels with great rapidity. Colloidal substances (fats, albumen, gum, gelatin, etc.) require to be digested and emulsified before they can be absorbed.
The Rectum will absorb many substances applied in the form of Enemata or Suppositories. Those most suited to this route are the salts of the alkaloids in solution, especially those of Morphine, Atropine, and Strychnine, the latter being absorbed more rapidly per rectum than by the stomach. Acid solutions, if not too frequently repeated, are also well administered by this channel.
The Respiratory Tract admits of the rapid absorption of medicinal substances through its extensive blood-supply. The inhalation of vapors or atomized fluids, the insufflation of powders into the nares, fauces, larynx, etc., and the use of a medicated nasal douche, are methods whereby this channel may be utilized.
The Veins are only used as a route of medication in emergencies, where the other channels are not available, and where immediate action is necessary to the preservation of life, the operation being a highly dangerous one. The injection intravenously of Saline Solutions in the collapse of cholera, diabetic coma, etc.,—Blood or Milk as a last resort in excessive hemorrhage, epilepsy, uræmia, the collapse of cholera, etc.,— and a solution of Ammonia for the bites of venomous reptiles, Hydrocyanic-acid poisoning, Opium narcosis, Chloroform asphyxia, etc., are the instances admitted in practice.
Arterial Transfusion has also been performed successfully in a number of cases, and is considered safer than venous transfusion when a large quantity of fluid has to be introduced into the circulation. A special apparatus is employed for these purposes, known as Aveling's Transfusion Syringe, but the ordinary Dieulafoy's aspirator, slightly modified, may be used with safety and convenience. The danger of the operation lies in the liability of the introduction of air into the circulation, an occurrence which may cause instant death in the human subject.
The Hypodermic Method is the introduction of medicines into the organism by injecting them into the subcutaneous areolar tissue, from which they are quickly absorbed by the lymphatic and capillary vessels. The great advantage of this method is the absolute certainty as to the quantity of drug actively affecting the organism, a very essential question when using small quantities, as with powerful alkaloids. Another is the avoidance of reactions between the drug and the secretions of the stomach, which may destroy the activity of the former, or seriously change its character. The Medicines must be in solution, of neutral reaction and freshly prepared, the usual menstruum being distilled water; though spring water filtered will answer just as well, and much better than distilled water which has been standing several days, and exposed from time to time to the air. The solution is to be injected beneath the skin, by a hypodermic syringe, care being taken to avoid puncturing a vein. The most suitable localities for the injection are the external aspect of the arms and thighs, the abdomen, the back, and the calves of the legs. On the external aspect of the thigh, just in front of the great trochanter, there is an area of some two inches square, over which the insertion of a fine hypodermic needle is not felt, so barren is the skin in that region of the sensitive nerve filaments.
After nearly filling the syringe with the solution to be used, the needle should be screwed on tightly; and with the instrument held in a vertical position, point uppermost, the excess of solution over the amount required should be ejected, thus expelling air-bubbles and filling the needle itself. A portion of skin should be grasped by the thumb and forefinger at the site selected for the injection, into which the needle should then be quickly inserted until its point has passed beneath the skin, when the piston may be pressed down slowly, delivering the solution so gradually as to avoid rupturing the tissue. If the solutions are freshly prepared with clean water, the needles kept clean and sharp, and the injection be made beneath the skin, not into it, there will be no risk of producing abscesses with the agents ordinarily employed. Tablets for hypodermic use are prepared by the prominent manufacturers, each containing one dose. They may be readily dissolved in a teaspoon at the bedside, and are very convenient for the pocket, if put up in a case with a good hypodermic syringe, as may be obtained from Parke, Davis and Co., of Detroit. Their regular line of Hypodermic Tablets includes the agents named in the following list, put up in tubes of 25 each.
Parenchymatous Injection is the delivery of a medicine deeply into the tissues, either to affect a muscle itself or to locally influence some important nerve-trunk. The principal agents used in this manner are Strychnine for palsied muscles, Chloroform for sciatic and other neuralgias, and Salts of Cocaine for local anesthesia.
The Skin is an active absorbent of crystalloidal substances when its epidermis or cuticle is removed. By this route there are four methods of introducing medicaments into the circulation, viz.-the Enepidermic, Epidermic, and Endermic Methods, and Inoculation.
The Enepidermic Method consists in placing the medicine in simple contact with the epidermis, no friction being used to hasten its penetration. Chloroform and Oleic Acid solutions of the alkaloids pass by osmosis in this manner with comparative ease, but aqueous solutions act very slowly and alcoholic ones with great difficulty if at all.
The Epidermic Method consists in the use of friction to promote the passage of the medicament between the cells of the epidermis. Mercurial Ointment, Cod-liver Oil, and other fats, Oleates, etc., are used in this way for their local and systemic effects.
The Endermic Method obviates the difficulty of absorption through the cuticle by removing the latter through the agency of a blister, and then powdering the medicament over the surface of the denuded derma.
An ordinary Cantharides-plaster, followed by a poultice to raise the blister, may be employed; but a quicker method is to place upon the skin a piece of lint soaked in Stronger Water of Ammonia, covering it with a watch-glass or a piece of oiled silk to prevent evaporation. The blister raises rapidly and should then be removed with scissors. Morphine, Atropine, Quinine, and Strychnine are the agents generally used in this manner, but the method is painful and unpopular.
Inoculation is the introduction of medicinal agents through the scraped or punctured skin by an operation similar to that employed for vaccination.
CLASSIFICATION OF MEDICINES.
In the present state of knowledge respecting the actions and uses of medicinal agents, no really scientific classification of these substances is possible. Some writers have adopted a system based on the natural relations of the various articles to each other, while many classify them according to their effects on the human system, and others make no attempt at arrangement but treat of them in alphabetical order. The latter method has been followed in this work, from a conviction that every medicine should first be studied as an individual, both with respect to its physiological actions and its therapeutical applications. When the student has thus made himself familiar with the characteristic features of each article of the Materia Medica, he may begin, by comparing one with another, to seek acquaintance with their more delicate lights and shades. Some system of classification then becomes imperative as an aid to the memory, and as the titles of the groups to which the various agents. belong in any physiological classification are also used to express their actions and uses, the following synopsis is inserted as an appropriate introduction to the section on Materia Medica and Therapeutics.
STIMULANTS AND SEDATIVES.
These are general terms employed in various classifications with very little discrimination.
Stimulant (Stimulus, a goad),—is a term which is used in various senses when applied to medicinal agents. Alcoholic preparations, which are true narcotics, are commonly termed "stimulants," and the same expression is employed to designate any agent which excites the organic action of a part of the economy.
Diffusible Stimulants are those which have a prompt but transient effect, such as Alcohol, Ammonia, Camphor, etc. Spinal Stimulants exalt the functions of the cord, as Strychnine, Picrotoxin, Ergot, Atropine, Phosphorus. Cardiac Stimulants increase the action of the heart, as Alcohol, Atropine and Morphine in small doses, Strychnine, etc., also Squill, Convallaria, Cimicifuga, and Digitalis, which slow but strengthen the cardiac action. Vaso-motor Stimulants, as Alcohol, Chloroform, Ether, Ammonia, Strychnine, Digitalis, and Squill, acting on the vaso-motor centre; and the Nitrites, Belladonna, Electricity, Volatile Oils, etc., acting as local dilators of the vascular system. Cerebral Stimulants, as Alcohol, Opium, Belladonna, Caffeine, Cocaine, Theine, Cannabis, Chloroform, Ether, Tobacco, etc. Renal Stimulants, as the diuretic group. Stomachic Stimulants,