STIMULANTS or Excitants (in medicine), agents which increase vital action, first in the part to which they are applied, then of the system generally, and perhaps ultimately of some particular organ ; and when this organ is a gland or secreting organ, a renewed or augmented secretion is observed. The nervous system seems to be the part which they chiefly influence, and through it the vascular, and in many cases the muscular. This is well seen in the simple effect following the employment of ammonia in a fainting fit, where the application of the vapour of ammonia, or its carbonate (smelling salts) to the nostrils, stimulates the brain, and so restores the heart's action, by which the circulation is resumed, and all parts dependent on it vivified. Aromatic vinegar, electricity, galvanism, and the sudden application of cold, especially alternated with heat, and chloric ether, have a like effect.
The agents which constitute this class, though often confounded with others, are perfectly distinct ; differing from all by their sensible qualities, their chemical composition, the nature of their physiological effects, and of the therapeutic indications they are calculated to fulfil. They are often confounded with tonics [Amserres], antispasmodics, and even narcotics, to all of which they have relations of affinity, but are not identical with any. In so far as they both act on the nervous system, they have most affinity with antispasmodics [ANTISPASMODICS], but differ from them inasmuch as stimulants increase the actions which are natural to the different organs of the body ; while antispas modics allay or diminish inordinate or abnormal action. Nearly the same may be said of the distinctions between them and narcotics [NARCOTICS], for though the increased action excited by an agent of this class, if extreme or long continued, is followed by a greater or less degree of collapse, still this is very different from that which follows the employment of a narcotic, which is much greater, as well as more speedy. Certain articles, such as opium and alcohol, may be made to act in either way; but while opium is not unfrequcntly used to stimu late, alcohol is never used medically as a narcotic, though the coma and stupor which ensue from all excessive dose of it are as profound, and often as fatal, as from an overdose of opium.
Above all, stimulants are most frequently confounded with tonics ; but independently of the consideration that stimulants operate directly on the nervous system, while tonics affect the muscular and sanguiferous systems, their operation, as well as the nature of their effects, is entirely different. Stimulants render the movements generally more frequent ; tonics render them stronger ; stimulants too freely or too often used, exhaust the excitability ; tonics, within a certain limit, maintain it. The action of the one is immediate and transient ; that of the other slow, scarcely perceptible, and progressive, but permanent. This is best seen in their effects on the stomach. Tonics render the digestion more perfect ; stimulants quicken it : moreover, most tonics must be themselves digested before the system can benefit by them ; while stimulants display their effects as soon as they touch the lips or reach the stomach. In many fevers cinchona bark produces no abatement of the symptoms for which it is usually prescribed, as the stomach is too weak to digest it ; but capsicum or cayenne pepper given along with it, so rouses the stomach that the febrifuge power of the bark is then manifested.
Stimulants are of two classes : one comprising medicinal suls stances; the other, warmth, cold, electricity, galvanism, and mental agents, such as music (when lively), joy, hope, &e. Many of the latter class have been already treated of [BAT[nso; ELECTRICITY; GAI.
vs.stsst] ; of the others, the effects are too familiar to require notice, except to recommend the practice of encouraging the hope of a favour able issue to his complaint in the mind of a patient, in all cases not desperate, as cherishing this feeling greatly increases the chance of recovery. The former class is divided into pernianent stimulants and diffusible stimulants, the effect of the permanent being slower but more lasting, that of the others quick but transient. The first are used where a considerable and enduring power is wished to be imparted to the system, as in the convalescence from acute diseases, the other where some great and impending danger is to be obviated, as in cases of fainting fits, or when sedative poisons are to be antagonised. In these latter instances, ammonia, alcohol in some form, or sulphuric ether, are commonly had recourse to. Permanent stimulants arc generally volatile or essential oils, pure, or in the combinations in which they exist in roots, barks, or flowers, and are often highly aromatic; malt liquors may also be classed with permanent stimulants. The precise stage in the progress of fevers and other acute diseases, when antiphlogistic or reducing measures should be abandoned, and stimulants substituted, is the nicest point that a medical attendant is ever called upon to decide ; and nothing more clearly distinguishes the judicious than his correct determination of this point. It may be safely asserted that more cases are lost by a premature use of them than by delay, as the numerous relapses in fever testify. All persons recovering from severe diseases are almost in the condi tion of newly born children, in whom the irritability and excitability are very great. These should not be violently acted upon, but on the contrary they should be treated with the utmost gentleness and care. Sleep is a more useful restorative than any other. Stimulants arc more during the night than during the day, and as more persons die during that period, the use of stimulants becomes more urgent at that time. But the best and most harmless is a very strong infusion of tea, especially green, given in small quantities, every hour or two, as the danger of the case may point out.
A useful stimulant is furnished by coca, the leaf of Erythroxylon coca (Lamarck), a shrub native of South America. Its power of enabling the Indians to sustain prolonged fatigue, either on journeys or while working in mines, has been long known. It has only lately been tried in Europe. Its utility seems manifest in cases of nervous exhaustion from over-study or long fasting. A few grains chewed, or an infusion of varying strength according to the necessity of the case, wards off fatigue and assists respiration. But too much caution can not be observed, lest a habit should be acquired, not less pernicious than the abuse of opium or alcohol. (See Piippig's Travels in Peru, an extract from which is in Companion to Botanical Magagne vol. i., p. 161, and with fig. vol. ii., p. 25; Weddell's Voyage dans le nerd de In Roll rie ; Johnston, Chemistry of Common Life, vol. p. 137, and The Technologist, vol. i., p. 255.) ST1 V Eli. [MONEY.]