14. Of Antispasmodics.
By these are meant whatever has a power of allaying inordinate motions in the system, particularly those involuntary contractions which take place in muscles naturally subject to the command of the will ; they counteract and remove various causes exciting contractions ; they dimi nish the influence of the nervous energy in the parts spasmodically affected. The changes induced in the system, from the primary effects of antispasmodics, are, the restoration of the proper balance of the nervous energy in different parts of the body, the restoration of the due influ ence of the will, and the restoration of the natural state of tension to the mus cles. The different articles referred to the class of antispasmodics may be distri buted into the two following orders : sti mulant, as volatile alkali, essential oils, ether ; sedative, as camphor, musk, opi um.
As the action of the medicines referred. to this class, depends entirely upon the presence of a morbid state, what has been advanced with regard to their nature, will, in a good measure, serve to illus trate their use. The indications of cure which, as antispasmodics, they are capa ble of fulfilling, are entirely to be derived from their influence on the nervous ener gy : whence they may be used, to remove spasmodic contractions taking place in different muscles, to allay convulsive agi tations. These indications may be illus trated and confirmed from practical ob servations concerning the effects of anti spasmodics, as employed in cases of epi lepsy and cramp. The circumstances claiming attention in the employment of antispasmodics, which respect either the nature of the medicine itself, the condi tion of the patient in whom it is used, or the necessary regimen, are different ac cording to the particular order which is employed. They will easily be under stood, from what has already been said of stimulants and sedatives, considered as separate classes.
There is, perhaps, no condition of the body which will contra-indicate the use of every individual referred to the class of antispasmodics. But the same morbid conditions, which have already been men tioned, as contra-indicating the use of sti mulants and sedatives, will likewise con tra-indicate the orders of antispasmodics denominated from these classes.
15. Of Narcotics.
These are medicines which have a pow er of diininishing the animal energy, and hence inducing torpor and sleep, during which this energy is usually recruited and restored. They diminish the sensi bility of the part to which they are parti cularly applied. They diminish the ac
tion and tonic power of its muscular fibres. They produce a peculiar sensa tion in the.system in general. They di minish the energy of the sensorium.
The changes induced in the system from the primary effects of narcotics are, retardation of the blood's motion in the part more immediately acted upon : di minution of the force of circulation in the system in general : diminution of excite ment in the powers of sensation and re flection : and diminution of vigour in mus cular action through the system.
Narcotics may be divided into those which act directly, and those which act indirectly. Of the former tribe are pop pies, opium, hyoscyamus, hops, and let tuce ; of the latter, neutral salts and acids. Their use may be calculated from the following sources : 1. From their af fecting the circulation ; whence they may be employed to diminish the force and celerity of the blood's motion where morbidly augmented ; to diminish the im petus of the blood against parts morbidly affected. 2. From their acting on the powers of sensation ; whence they may be employed to abate violent pain ; to procure sleep, in cases of preternatural watchfulness. 3. And from their acting on the moving fibres; whence they may be employed to restrain inordinate mo tions, and to moderate excessive evacua tions. These indications may be illus trated and confirmed f'rom practical ob servations concerning the effects of this class of medicines, as employed in cases of inflammation, tooth-ach, and dysente ry. The cautions to be observed in the employment of this class of medicines, as derived from their nature, chiefly re spect the insensibility which they pro duce ; the stony they occasion in the muscular fibres, particularly in the blood vessels ; and the suspension of the pow ers of sensation with which they are sometimes followed. The conditions of the system which chiefly require atten tion in their employment are, irritable and relaxed habits ; and such as are con stitutionally liable to delirium from their use. The circumstances chiefly to be at tended to in the necessary regimen, re spect the regulation of the dose of the medicine employed ; the avoiding all sti mulating causes during their operation ; and the guarding against their becoming habitual to the system. Narcotics are chiefly contra-indicated by a preternatu rally languid circulation ; a peculiarly le thargic disposition, and great morbid tor por in the system.