Aconite, Veratrum, Muscarine, Pilocarpine, Saponin and Prussic Acid are direct cardiac poisons, depressing the heart muscle and the cardiac motor ganglia; Muscarine and Pilocarpine also stimulate the inhibitory ganglia; Digitalis stimulates the vagus centre and the cardiac muscle, and acts as a sedative in many cases by slowing the rate and giving it a regular rhythm. Aconite is said by some authorities to relax inhibition, by others to stimulate the vagus centre. Antimony depresses the motor ganglia, Potassium the cardiac muscle. Vascular Stimulants produce dilatation of the peripheral vessels, and increase the rapidity of the circulation, thus equalizing the bloodpressure and preventing internal congestions. The most useful are Alcohol and Ether, as they stimulate the action of the heart simultaneously with the vascular dilatation. The chief members of this group are: Alcohol. Nitrous Ether. Amyl Nitrite. Liq. Ammonii Acetatis. The dilating action of Amyl Nitrite and other Nitrites is due to weakening either of the muscular walls of the arterioles or to paralysis of the vaso-motor ganglia in them. Alcohol, Ether and Opium probably depress the vaso-motor centre. Vascular Tonics produce increased contraction of the arterioles and consequently increased blood-pressure. The most important are Digitalis. Iron. Opium, in small doses. Strychnine. Lead and Silver. These agents act upon the local vaso-motor mechanism in the walls of the vessels, which are also directly stimulated by cold produced in any way, as by Ether spray, or evaporating lotions containing Alcohol, Vinegar or Ammonium Chloride. Vascular Sedatives increase the contraction of the vessels and lessen the circulation through them. They are employed to check hemorrhage and to cut short a local inflammation. The chief agents belonging to this group are— Cold. Hamamelis. Opium. AGENTS ACTING ON THE DIGESTIVE SYSTEM. Dentifrices (dens, a tooth, frico, I rub),—are medicated powders or pastes employed to cleanse the teeth and gums. Chalk is the basis generally used, for its mechanical action and its alkaline quality. Antiseptics, as Borax, Quinine, Carbolic Acid, etc., should also be employed so as to prevent the acid fermentation of food products between the teeth and the consequent decay of the dentine. Tincture of Myrrh is an excellent ingredient, being an aromatic local stimulant and disinfectant. Many drugs affect the teeth injuriously, such being the Mineral Acids, Persalts of Iron and Alum. The first two should be taken through a glass tube, and the mouth should AGENTS ACTING ON THE DIGESTIVE SYSTEM. 35 be afterwards rinsed with a weak alkaline wash. Opium, Chloral, Cocaine, Carbolic Acid, Creasote, Chlorate of Potassium and Aconite are the agents used as local anodynes in toothache from caries exposing a nerve filament. Chloral should never be used for this purpose, as in solution sufficiently strong to be of any service, it will cause sloughing of the gum, especially if injected thereinto with a hypodermic syringe, as is frequently done by ignorant dentists. Sialogogues (seealon, saliva, ago, I carry off), -are agents which increase the secretion and flow of saliva and buccal mucus, either by reflex action from the local irritation produced when anything is taken into the mouth, or by stimulating the glands during their elimination. The principal sialogogues are divided into two classes, the first (topical) acting by reflex stimulation, the second (general) acting through their systemic influence on the glands or their secretory nerves. They are as follows: Topical Sialogogues. Ether, Chloroform, etc. Pyrethrum, Mezereon. Tobacco, Cubebs. Capsicum, Rhubarb. Horse-radish. General Sialogogues. Pilocarpus (Jaborandi). Physostigma. Mercurials. Iodine compounds. Antimonials. Tobacco, Ipecac. Antisialics (anti, against, seealon, saliva),-are remedies which diminish the secretions of the salivary glands. Atropine is the principal agent. of this group, acting by paralyzing the terminations of the nerves of secretion. Physostigma counteracts this paralysis, but in large doses acts as an antisialic by lessening the blood supply to the glands. Opium diminishes the reflex excitability of the reflex centre and also diminishes the secretion. Others acting locally are Borax. Potassium Chlorate. Soda. Lithia. Insipid or nauseous articles of food or medicine. Refrigerants (refrigero, I cool),—are remedies which allay thirst and impart a sensation of coolness. They include the Vegetable Acids, the Mineral Acids (greatly diluted), Ice, Water, if cold, Effervescing drinks, Fruit juices, and many diaphoretics. Gastric Tonics or Stomachics,-are agents which increase the appetite and promote gastric digestion. They include a number of substances, dietetic and medicinal, some acting by stimulation of the production of gastric juice, others by stimulating the local circulation, and several by exciting the activity of the nervo-muscular apparatus of the stomach. The first indication is met by the use of dilute alkaline solutions before meals,-the second by administering any of the pungent carminatives, as the Aromatic Oils, Pepper, Mustard, etc., or by Alcohol and Ether in small doses, or by the Aromatic Bitters, as Gentian, Orange, etc., or the simple bitters, as Calumba;-while the third desideratum is secured by the use of such agents as Nux Vomica, Hydrastis, Arsenic, the dilute Mineral Acids, and the Volatile Oils. Adjuvants to gastric digestion are the various digestionferments, Pepsin, Ingluvin and dilute HCl Acid, which may be used to supplement the gastric juice when deficient in quantity or quality. Acids, considered therapeutically and physiologically, are medicines which in concentrated form act usually as caustics, and when given in medicinal doses internally check the secretions of organs producing acid secretions with which they come in contact, and increase those of organs producing alkaline secretions. Thus a dilute acid given before meals will check the production of the acid gastric juice, but will stimulate that of the alkaline pancreatic juice. The chief members of this group are the following, which should be given in very dilute form: Acidum Aceticum. Acidum Citricum. Acidum Hydrochloricum. Acidum Nitricum. Ant-acids or Alkalies,-from the same stand-point, are remedies which neutralize acids, check alkaline secretions and stimulate acid secretions, when in contact with the ducts of the organs producing them. Thus a dilute alkali given before meals will stimulate the production of the acid gastric juice and if applied to the mouth of the pancreatic duct will check the secretion of the alkaline pancreatic juice. The principal articles which belong to this group are the following, which should always be administered in dilute solution : The substances in the first list are direct antacids, lessening the acidity in the stomach, and many of them also acting as remote antacids, lessening the acidity of the urine, as Potash and Soda, and their Carbonates and Bicarbonates. Ammonia and its Carbonates after absorption are eliminated as urea, and do not lessen the acidity of the urine. The salts in the second list are remote antacids, do not lessen acidity in the stomach, but do that of the urine, being oxidized in the blood and excreted as Carbonates. Emetics (eemeo, I vomit),-are agents which produce vomiting. They may be subdivided into two groups, (1) Local Emetics, or those which act by irritating the end-organs of the gastric, pharyngeal or œsophageal nerves, and (2) General or Systemic Emetics, which act through the medium of the circulation. Both these classes produce the emetic action by irritation of the vomiting centre in the medulla, the first by reflex, the second by direct stimulation. The principal emetics are the following named: AGENTS ACTING ON THE DIGESTIVE SYSTEM. Local Emetics. Alum, Mustard, Salt. Ammonium Carbonate. Zinc and Copper Sulphates. Vegetable Bitters, as Quassia, in strong infusions. General Emetics. Ipecacuanha. Senega. Squill. 37 Tartar Emetic, Ipecacuanha and probably Apomorphine, act locally as well as systemically, for if injected subcutaneously they are excreted by the stomach in part, thus irritating the gastric nerves as well as the vomiting centre. Pilocarpus is a local emetic, and Digitalis and its congeners, also Muscarine, are systemic emetics, but none of these agents are used medicinally for that purpose. Opium, Morphine and Codeine usually produce emesis as one of their after effects. Anti-emetics,—are agents which diminish nausea and vomiting, some by a local sedative action upon the end-organs of the gastric nerves, others by reducing the irritability of the vomiting centre in the medulla. The most efficient of the local sedatives is Ice, swallowed in small pieces. Astringents are very useful when there is congestion of the gastric mucous membrane, as in the vomiting of alcoholism and phthisis, where Silver Nitrate and Alum are respectively effective. The most important antiemetics are the following, viz.:— Vomiting being set up by irritation of many afferent nerves from various regions of the body, or by impulses from the brain excited through impressions on the nerves of special sense, the measures for combating it are very diversified. (Compare the title VOMITING in Part III.) Gastric Pain is best treated by such local sedatives as Bismuth, Hydrocyanic Acid, or small doses of Morphine, Arsenic and Belladonna. Cocaine is one of the most efficient agents of this class, in 5 to 6 minim doses of a 4 per cent. solution, every hour. As its general action is opposed to that of Opium, Bromides, etc., it must act locally, and therefore should be given by the mouth. Carminatives (Carmino, I soothe),-aid the expulsion of gas from the stomach and intestines, by increasing peristalsis, stimulating the circulation, and relaxing the cardiac and pyloric orifices of the stomach. They also act as diffusible stimulants, both of the bodily and mental faculties. The principal carminatives belong to the aromatic oils, alcohols or ethers, and are embraced in the following list: Asafetida. Chloroform. Mustard. Spirits. Oil of Eucalyptus. Oil of Peppermint. Oil of Anise. Oil of Spearmint. Cathartics or Purgatives (kathairo, purgo, I cleanse),-are agents which increase or hasten the intestinal evacuations. According to their respective degrees and direction of action they are subdivided into several groups, as follows: Laxatives (laxo, I loose), or Aperients (aperio, I open),-include those which excite moderate peristalsis, and produce softened motions without irritation. Sulphur is the typical laxative. Simple Purgatives,-increase peristalsis actively, and stimulate the secretions of the intestinal glands, producing one or more copious and semifluid motions with some irritation and griping. Senna is the type of this group. Drastic Purgatives (drao, I act),-act still more intensely, producing violent peristalsis and watery stools, with much griping pain, tenesmus, and borborygmi. They irritate the intestinal mucous membrane, cause exosmosis of serum from its vessels, and in large dose set up inflammation and symptoms of irritant poisoning. Jalap is a typical drastic. Saline Purgatives,-consist of the neutral salts of metals of the alkalies or alkaline earths. They stimulate the glands, increase peristalsis, promote osmosis and cause free watery evacuations. Magnesium Sulphate is a typical saline. Hydragogue Purgatives (heudore, water, ago, I bring away),—include the most active of the drastic and saline groups, those which remove a large quantity of water from the vessels. Elaterium is a typical hydragogue. Cholagogue Purgatives (kohlay, bile, ago, I bring away),-are those agents which stimulate the flow of bile and produce free purgation at the same time, the stools being green-colored, or "bilious," and liquid. Podophyllin is the type of this group. The principal Cathartics are the following named: -- |