Certain stimulant Eliminatives are employed for the purpose of checking mucous fluxes, and so far simulate the action of true Astringent medicines. Thus we administer, with more or less advantage, Aromatics in diarrhœa; Cubebs, Copaiba, and Turpentine, in gonorrhœa; and Balsam of Peru, and other oleo-resins, in Catarrhal affections. These medicines all act upon and pass through the glands of the several mucous surfaces which they affect: while so doing, they stimulate the healthy function and secretion of the gland, and cause it to displace the morbid one. Dr. Williams thinks that they first cause dilatation of the vessels of a gland, and that this is followed by contraction. There is no apparent reason why the latter effect should succeed the former. But supposing contraction to take place in this way, then these medicines would be true Astringents. But it cannot be so, for they do not diminish any of the natural secretions, but, on the contrary, increase them. Turpentine, Cubebs, and Copaiba, are Diuretics, and it is possible that while passing out in the urine they may simply stimulate the mucous surface of the inflamed urethra, and excite it to a healthy action.
These volatile oils are incapable of exerting a true astringent action. On the supposition that it is really an Astringent, Turpentine has been often prescribed as a remedy for hæmorrhages in different parts of the body. But it has very much disappointed the expectations that were entertained of its efficacy.
General Stimulants may act indirectly as styptics to a mucous surface, when relaxed and bleeding on account of an atonic condition of the nerves by which the contraction of the minute vessels is maintained.
Alcohol, in large quantity, coagulates albumen, and it may thus act as a true Astringent when applied externally.
Some Neurotic medicines diminish secretions in a way which is not well understood. The chief of these is Opium, which particularly diminishes the secretion of the bowels. Attempts have been made to explain this by an influence possessed by Morphia on the process of Endosmosis, but they are not satisfactory. Some little light may perhaps be thrown upon the matter by a consideration of the other operations of Opium; but it is difficult to explain it decisively in any way.
Prop. X.—That a fourth class of medicines, called Eliminatives, act by passing out of the blood through the glands, which they excite to the performance of their functions.
In this Fourth Class are included all the medicines which tend in a direct manner to increase secretion. They have received various appellations: some authors have called them special Stimulants; others, as Dr. Duncan, have named them Evacuants; while Dr. Pereira entitles them Eccritics.
The mode of operation of Eliminative medicines is a matter of considerable importance, and its consideration will require us first to make some inquiry into the character and functions of those important glandular organs which they are said to excite to action.
The rational explanation of the process of elimination or secretion has been in all ages of science a favourite topic for speculators and theorists,—sound or unsound in their views, according to the light that was given to them. With regard to its essential nature, and its immediate bearing on the cure of disease, the subject has been generally understood with tolerable clearness. From the time of Hippocrates downwards, the use of Evacuants in the treatment of fevers and other disorders has been recognised, and their efficacy usually explained by supposing that they caused the passage out of the body through the glands of certain matters that were formed in the blood, but ought not to remain in it.
This view was more particularly insisted on towards the close of the seventeenth century by Dr. Thomas Sydenham; and again at the commencement of the eighteenth by Dr. A. Pitcairn, in an Essay on the use of Evacuants in Fevers. These both had observed that fevers and other disorders had mostly a particular tendency to pass off with an increase in one or more of the secretions; and they drew from this, and from the results of their experience, that in stimulating and urging this secretion, the physician would be doing his best to promote a cure. (Vide page 55.) More recently the same idea has been followed up by Cullen, Hamilton, and others.