This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This implies a diminution of action. Like stimulation it may be general or local. General sedation may affect especially either the circulation and its dependent functions, or the nervous system. The agents which produce the former effect I denominate arterial sedatives. They are the refrigerants of other writers: as they reduce temperature along with vascular action. Those operating upon the nervous system may produce their depressing effect in two ways; in one, by directly affecting the functions of the nervous tissue wherever they encounter it: in the other, by acting primarily on the brain, and through the cerebral centre.-depressing the dependent nervous functions. The former may be called simply nervous sedatives, the latter may be distinguished by the title of cerebral sedatives. It is important to understand that general nervous sedation may result even from the cerebral stimulants, through this dependence of function. In this case, the nervous centres are overwhelmed by an active congestion, which cripples their power both of receiving im-pressions and transmitting influence; and sensibility, muscular motion, and in fact all the functions which derive a necessary support from the brain are more or less impaired. This distinction is of great practical value. Thus, hydrocyanic acid, tobacco, and acetate of lead might be used as sedatives, when it might not be altogether safe to employ alcohol or opium.
The agents of sedation will be enumerated" and described hereafter.
Local sedation may affect all the constituent tissues of a part, or more especially the nervous. In the former relation, it is employed to repress inflammation, or vascular irritation as shown in morbid secretion, hemorrhage, or simply congestion; in the latter, to relieve neuralgic-pain, and allay spasm.
Many of the general sedatives may be employed locally for these purposes.