A manual of legal medicine : for the use of practitioners and students of medicine and law / by Justin Herold.

Date:
1902
Catalogue details

Licence: In copyright

Credit: A manual of legal medicine : for the use of practitioners and students of medicine and law / by Justin Herold. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    Modification of the Action of Poisons.—The most important of the modifying agencies connected with the poison itself is the quantity or dose. As a general rule, the larger the quantity the quicker the effect. For example, there are many drugs which are exceedingly poisonous in large doses, while in small amounts they prove useful as valuable remedies ; such substances are arsenic, opium, digitalis, prussic acid, etc. Then, again, the mode of administration is of consequence. Dilute diuretics, for instance, act more powerfully than when concentrated, while saline purgatives have better effect when given in the latter condition. The chemical constitution of a poisonous substance is an important modifying agent. The more soluble a compound is, the more speedily are its effects pro- duced. Inert substances are those which are insoluble in water, yet certain conditions of the digestive organs must be considered when discussing them. Thus, orpiment is insoluble in water, but when administered internally may show signs of poisoning. The poisonous material, to be absolutely inert, must be insoluble not only in the suspending fluid, but also in the digestive fluids, else it might find its way into the system, thereby causing fatal results. Some persons are more susceptible to the influence of poisonous sub- stances than others. A tolerance to certain poisons is a bodily condition influenced, to a certain extent, by habit. When a substance is habitually taken into the system, the latter becomes accustomed to its effects, and larger quantities are necessary to reproduce them. This is well seen in the arsenic-eaters of Styria and other mountainous countries, where enormous quantities of arsenic are annually consumed, and in a less degree in the practice of opium-eating and smoking as observed throughout the civilized world. Men generally bear larger doses of poison than women ; and, as a rule, the larger and more robust the individual, the less easily is the influence of the drug shown. Some persons are very susceptible to the effects of certain plants, while others may even handle them with perfect impunity. Some are easily influenced by minute doses of arsenic ; others cannot take quinine, opium, belladonna, etc. ; and in others very dilute solutions of otherwise harmless preparations may cause the most alarming symptoms. ( Vide p. 55, foot-note.) Mental and bodily conditions play an important part in the modification of the action of poisons. Sedatives produce no effect in certain convulsive disorders, though they may produce serious results when administered to otherwise healthy individuals. Again, there are certain animal and vegeta- ble substances, such as the venom of reptiles, and curari, most virulent when introduced into the blood, which may be swallowed with perfect impunity. The active ingredients of various articles of food are sometimes virulent poisons. During the process of digestion larger amounts of poisons are borne than can be taken when abstaining from food.