INFLUENCES THAT MODIFY EFFECTS OF MEDICINES. 31 as a rule, they bear larger proportionate doses of purgatives. No scheme for calculating the doses from the age of the patient alone can be relied on in practice. What is Dr. Young's rule for calculating the dose for children? Convert the child's age into a fraction by using the age itself as a numerator and the age + 12 as a denominator, the result being the proportion of the adult dose which should be administered to the 3 3 1 of that of the adult. At 3+12 15 5 child. Thus, at three years 21 years of age the full dose is given. What is Dr. Cowling's rule? Dr. Cowling proposed to divide the patient's next birthday by 24; thus, at three years the dose would be 4 1 24 6 of that of the adult. How may the dose for a child be more easily calculated in the metric system? Dr. Lauder Brunton proposes to multiply the next birthday by 4 and divide the result by 100; or, what is the same thing, to multiply the full dose by the child's next birthday, then by 4, and remove the decimal point two places to the left. Thus, if the dose for an adult 1X4X4 be 1. Gm., that for a child of 3 years will be 100 =.160 Gms. How do sex, idiosyncrasy, constitution and habits influence medicinal effects? Men generally bear larger doses of medicines than women. Many persons manifest idiosyncrasies with respect to certain drugs; thus, some are very susceptible to the poisonous effects of even minute doses of arsenic; others cannot take quinine or opium or belladonna or the iodides, and in others very dilute solutions of cocaine applied to the mucous membranes may cause alarming symptoms. As a rule, the larger and more robust the individual, the less easily is he influenced by drugs. When a medicine is habitually taken, the system becomes tolerant to it, and larger doses are required to produce any effect, This is especially the case with opium and purgatives, In what way does the condition of the digestive and absorbent symptoms modify the effects of medicine? During digestion, larger amounts of medicine are borne than can be taken fasting. In certain conditions of the alimentary canal, as in the third stages of yellow fever and of cholera, during a congestive chill of the gastro-enteric variety, or during profound opium narcosis, absorption from the stomach is slow, if it take place at all. What effect does disease have upon the influence of medicines on the system? In certain diseases great tolerance is manifested to medicine; thus, in peritonitis and cerebro-spinal fever enormous doses of opium are taken with advantage; in typhoid fever the tolerance to alcohol is marked. Does the method of administration modify the effect of medicines? It does: diuretics act more powerfully when much diluted; saline purgatives when concentrated. Usually medicines act more rapidly and powerfully when given by the mouth than when administered per rectum; still more so when injected under the skin, and most powerfully when injected into the blood. How may medicines be administered? Medicines may be administered by the skin, being either applied without friction (enepidermic method), or with friction (epidermic method), or else directly to the derma, which has been denuded by means of a blister (endermic method). They may also be given hypodermically, by means of a small syringe armed with a long, hollow needle. When thus administered, the dose should be from one-half to two-thirds of that which is required by the mouth, and the medicine should be in a thorough state of solution. Medicines are also applied to all the mucous tracts in the form of solutions, vapors (by atomization), powders (by insufflation), etc. The gastro-intestinal tract is most generally used when a systemic effect is desired, and the remedy is given either by the mouth or by the rectum. Suppositories and ointments are occasionally used per vaginam for their influence on the system. The broncho-pulmonary mucous membrane is used for the inhalation of vapors, as ether. Intravenous injection is rarely practiced except as a last resort. How are medicines classified? Medicines are usually classified either according to their physiological action or to their therapeutic uses. The latter is the better arrangement. The difficulty of grouping medicines is increased by the fact that even as yet the study of pharmacology is in its infancy, so that the exact physiological group to which many of them belong is not definitely determined. The action of most medicines, also, is complex, affecting different organs at the same time, and in many instances varying much according to the dose and the manner of administration. They may be divided accordingly into GROUP 1.-SYSTEMIC MEDICINES. Class 1.—Medicines acting on the body at large by their influence on digestion, nutrition (tissue waste and repair), and calorification. Order I. Digestants. Order II. Tonics. Order III. Altera tives. Order IV. Antipyretics. Class 2.-Medicines acting on the body by their effect on its various organs. A. On the Nervous System: Order I. Hypnotics. Order II. Mydriatic Anodynes. Order III. Anæsthetics. Order IV. Antispasmodics. Order V. Excito-motors. Order VI. Depresso-motors. B. On the Organs of Circulation:— Order I. Stimulants. Order II. Sedatives. C. On the Sexual Organs: Order I. Aphrodisiacs. Order II. Anaphrodisiacs. D. On the Alimentary Canal: Order I. Emetics. Order II. Gastric Sedatives. Order Order Order III. Order V. Anthel- ! : Class 3.—Medicines Acting on the Various Secretions :Order I. Diuretics. Order II. Diaphoretics. pectorants. Order IV. Astringents. acids. Order III. ExOrder V. Ant GROUP I.-SYSTEMIC MEDICINES. Class I.-Medicines Acting on the Body at Large by Their Influence on Digestion, Nutrition (Tissue Waste and Repair) or Calorification. ORDER I.-DIGESTANTS. What are digestants? Digestants are animal or vegetable substances given to aid digestion when the normal alimentary secretions are insufficient for this function. Name the digestants. 1. Pepsinum (pepsin), a proteolytic ferment obtained from the glandular layer of fresh stomachs from healthy pigs. 2. Ingluvin, a preparation from the gizzard of the domestic chicken. 3. Pancreatinum ( pancreatin), a mixture of the enzymes naturally existing in the pancreas of warm-blooded animals, usually obtained from the fresh pancreas of the hog (sus scrofa). 4. Papain, a ferment obtained from the fruit of Carica papaya (Nat. Ord. Papayacea), a tree of South America. What are the physiological actions of these substances? 1. Pepsin (when combined with an acid) digests albumen, which it converts into albuminose. 2. Ingluvin also aids the digestion of albumen, this action being probably due to a bitter principle which it contains and which stimulates the gastric glands. 3. Pancreatin (in neutral or alkaline solutions) converts albumen into albuminose and starches into glucose and aids in emulsifying fats. 4. Papain digests albumen and dissolves false membranes, ascarides and tænia. What are the therapeutic uses of the digestants? 1. Pepsin is useful when the secretion of the peptic glands is not sufficient for the purposes of digestion, as in atonic dyspepsia, apep |