NARCOTICS (from the Greek adjective vapaarrtah, which is from rapah, a stiffening, stupor, or insensibility), a class of medicines which may be defined—agents which, in moderate doses, cause a temporary increase of the action of the nervous and also of the vascular system, followed more or less speedily by a marked diminution of this action, terminating generally in sleep. When the dose is large, the excitement is scarcely perceptible ; while the diminished power of the nervous system is so manifest, that an appearance of coma or apoplexy is induced. All the agents included in this class are capable of producing a state termed narcosis, or narcotism, which, if not quickly removed by a natural subsiding of their influence, or by artificial means, may terminate in death. Many of them are therefore as familiarly known as poisons as therapeutic agents. It is the consideration of them how ever in this latter quality which is to be entered on in this place. Their power of inducing sleep has procured for them the name of hypnotics, or soporifics; and the property which many of theta possess of alle viating pain, by blunting the sensibility, has obtained for them the appellation of anodynes [AxonrxEs], or, from one of the best known among them, simply opiates.
The most important consideration respecting ;them is the circum stance of their depressing action being always preceded by a stimulant. This peculiarity renders their employment difficult in some cases and improper in others. " Narcotics must be distinguished from stimulants on the one hand, and from sedatives on the other ; and the distinction is the more necessary, because in nature the narcotic principle is gene rally combined with one or other of these : hence the contradictory and unsatisfactory reports of the value of different narcotic remedies, and the difficulty experienced in their application by those who do not know the reason why opium suits one case, hyoscyamus another." (Billing's ' First Principles of Medicine,' 3rd edit.) The progress of chemistry, by isolating the various active principles existing in the same natural compound, has lessened the difficulty attendant on their administration ; still, as no one can be said to act in a manner precisely similar to another, a correct knowledge of each is desirable in order to ensure the selection of that which is best suited to the case. Diversified
as they are in their nature and modes of action, there is this common propertp.that they all make a direct impression on the extremities of the nerves (to whatever part of the body, with few exceptions, they are applied); but their full and ultimate eTfects do not take place till they are absorbed, and mingled with the circulating fluid.
A slight glance at their action on the different systems of the body will furnish a useful guide in their administration. A full dose of a narcotic introduced into the stomach will, if that organ be empty, destroy the dgsire for food, while, if it contain food, the digestive pro cess is suspended or rendered slower. Their frequent or continued use is therefore very injurious to that function, on which all the others depend, namely, nutrition ; as is displayed in the persons of opium eaters of the East. Further, should any considerable irritation or subacute inflammatory condition of the mucous coat of the stomach exist, they cause an aggravation of the febrile symptoms, and either iu common or cancerous ulceration of that organ they cause great uneasi ness. Though their primary effect on the vascular system be stimu lating, and many of them send thereby a large quantity of blood to the brain (probably the source of their soporific property), their secondary effect is depressing; and in this the respiratory organs participate. This is at once a source of utility and of danger, for by moderating the action of the heart and lungs, the respiration is rendered slower, an advantage in most inflammatory complaints ; but when pushed too far, the blood is not sufficiently aerated, and partaking too much of the nature of venous blood, it does not prove a sufficient stimulus to the brain and other organs.