Dr. Joy as substances which speedily augment the action of the part to which they are immediately applied, and, subsequently, after a very brief interval, that of the system at large, through the medium of sympathy.
Medicines of this class, especially when introduced into the stomach, exalt at once the sensibility of the nervous system, and the action of the muscular fibre, as well as that of the mucous membrane. They augment the strength and frequency of the heart's pulsations, give vigour to the play of the lungs, and raise the temperature of the whole body. In some instances they prove excitant, and even irritant, to the urinary organs. In their mode of action, they approach most nearly to narcotics and tonics. The former, indeed, if regard be had only to their primary action, are not always satisfactorily distinguished from stimulants. From tonics they differ, and especially the so-called diffusible stimulants (Alcohol, &c), in the rapidity and the comparatively evanescent nature of their action, in their power of increasing the susceptibility to external impressions, and the tendency they have to be followed by exhaustion, when once their action is expended. The great majority of vegetable substances exerting a stimulant power are indebted for it to the presence of an essential oil. Camphor, Ether, or Ammonia, manifest the same quality in a very marked degree. Fermented liquors, too, from the Alcohol which they contain, rank high in the class of excitants, both in respect to their beneficial results when judiciously exhibited, and their injurious consequences when unnecessarily or too freely employed. Their habitual use, and more especially the frequent employment of those of a very stomachic or spirituous character, ought to be discouraged, as, from the agreeable but treacherous excitement, both mental and corporeal, which immediately follows their exhibition, as well as from the distressing feelings of collapse which ensue upon the termination of their action, forthwith suggesting instinctively the desire of a repetition of the dose in a still stronger form, a tendency to confirmed dram drinking is apt to be the result. (Dr. Joy.*)
The above lengthened extract has reference principally to general or diffusible stimulants. There is, however, another class which requires separate notice; namely, those whose action is apparently local, and which have consequently been designated specific stimulants. So great is their number, and so diversified are their characters, that if all the medicines which, strictly speaking, belong to this class were rigidly included, it would embrace in its range most diuretics, emmenagogues, expectorants, errhines, sialagogues, many cathartics, and, in fact, all those classes of medicines, however designated, which stimulate the action, and increase the secretion of any particular organ of the body. Of special stimulants, we may mention as examples, terebinthinate medicines, upon the mucous membrane of the bronchi and air-passages; cantharides, upon the mucous coat of the genito-urinary organs and the neck of the bladder; and Nux Vomica, with its alkaloid, Strychnia, upon the excito-motory function of the spinal cord.
The objects for which they are employed. 1. To exalt a depressed state of the vital functions. 2. To remove exhaustion and debility. 3. To correct certain nervous affections, as Hysteria, &c, depending upon debility. 4. To increase secretions from particular organs.