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GROUP XIII
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See also:GROUP XIII . See also:Local Irritants.—Although some of the drugs already considered have a local irritant See also:action, they produce other more important effects, but the substances here ranged under this heading depend entirely for their action on their local irritant effects. a. Those which See also:act upon the alimentary See also:canal: See also:Simple See also:bitters such as See also:quassia See also:wood, columbo See also:root, See also:taraxacum, See also:gentian, chiretta, and many others, irritate gently the mucous membrane of the See also:stomach and bowels, and by increasing the secretions improve the appetite and digestion. The aromatic bitters such as See also:chamomile See also:flowers, cascarilla bark, hops, See also:orange See also:peel and others contain in addition small quantities of essential See also:oils which increase their local action. The active principles in some of these bitters have been isolated pure, and have been found to be alkaloids or neutral compounds. Substances like See also:pepper, See also:cayenne pepper, See also:mustard, See also:horse-See also:radish and See also:ginger irritate the stomach and bowel much in the same way, but are more pungent, and are consequently used as condiments. Some of these have a similar but less marked effect upon the skin. The large number of See also:vegetable substances used as purgatives owe their action to an irritating effect upon the mucous membrane and the neuro-See also:muscular apparatus of the bowel, whereby the secretions and peristalsis are more or less increased, as the result of which See also:diarrhoea ensues. Some of them cause so much irritation that the See also:discharge is very watery (hydragogue cathartics), while others, for example aloes, by acting gently on the See also:lower See also:part of the bowel and on its muscular coat, produce simply a laxative effect. A few of them, such as aloin and colocynthin, are also purgative when injected subcutaneously or into the See also:blood, probably owing to their being excreted into the intestinal canal. b. Those which act on the skin: The best known of these is See also:cantharides (See also:Spanish See also:fly), the active principle of which is a See also:colour-less crystalline See also:body—cantharidin—which is extremely irritating. On a mucous membrane or a delicate skin it exerts an irritant action, which occurs more quickly than on a thickened epidermis, such as the See also:scalp, and according to the strength and See also:period of application there may result redness, a See also:blister, or an See also:ulcer. Many other substances, such as chrysarobin, mustard, pepper, &c., are also capable of irritating the skin, the effect produced varying from See also:mere See also:dilatation of the cutaneous vessels to destruction of See also:tissue. GaouP XIV. Male-See also:fern.—This includes the male-fern, See also:santonin, cusso, See also:pomegranate bark, See also:pumpkin seeds and many other substances containing active principles which have a specific poisonous action on intestinal parasitic See also:worms. Apart from this their actions vary considerably, but are of little See also:practical importance. Geoup XV. Ethereal Oils.—This includes a very large number of substances which owe their action to the fact that they contain ethereal or essential oils. The best known of these are See also:cloves, See also:pimento (allspice), See also:myrtle, See also:eucalyptus, See also:caraway, See also:fennel, See also:dill, See also:coriander, See also:rosemary, See also:lavender, See also:peppermint, spearmint, See also:nutmeg, See also:cinnamon, See also:sandal-wood, See also:turpentine, See also:juniper berries, See also:valerian and See also:sumbul. In this group may be included the oleo-resins, such as See also:copaiba, See also:cubebs and See also:Canada See also:balsam; the See also:gum-resins, such as asafetida, See also:myrrh, See also:ammoniacum and See also:galbanum; and the true balsams, such as See also:benzoin, storax, balsam of Tolu and balsam of See also:Peru. The resins when taken internally have much the same action as essential oils, which are closely allied chemically, while the benzoic and cinnamic acids in the balsams modify their actions very slightly. Although individual essential oils may differ somewhat in action, chemically and pharmacologically they are fundamentally similar. They all have a poisonous action on See also:protoplasm, which makes them useful in See also:medicine as See also:antiseptics, See also:disinfectants, germicides, See also:anti-fermentalives and parasiticides; when locally applied they are more or less irritating, and, when very dilute, astringent. When swallowed in small doses they slightly irritate the mouth and gastric mucous membrane, increasing the secretions and producing a feeling of warmth. At the same See also:time they increase the movements of the stomach, and also in this way hasten digestion, an action which extends to the upper part of the bowel. They are readily absorbed into the blood, and they are excreted chiefly by the kidneys in a more or less altered See also:form, and probably also by the different mucous membranes, and even by the skin. After absorption their action, speaking generally, is exerted on the See also:brain and See also:spinal See also:cord, and is at first slightly stimulant and afterwards depressing, even to the causing of sleepiness and stupor. Locally applied they depress the terminations of sensory nerves, and may thereby lessen See also:pain. On the See also:heart and circulation the effects are stimulant unless large doses are given, when the See also:pulse becomes slow and blood-pressure much lessened. During See also:excretion they irritate the kidneys and the sweat-glands, and thereby increase the excretion of urine and of sweat. They also increase the number of leucocytes in the blood,and the more irritating of them increase the flow of blood to the pelvic See also:organs, and may thus stimulate the uterus, or in large doses cause See also:abortion. The various See also:camphors, such as See also:laurel camphor, See also:Borneo camphor, menthol and cumarin, are oxidized derivatives of essential oils, and differ only superficially from them in their action. Additional information and CommentsThere are no comments yet for this article.
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