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.
There is reason to believe that diarrhoea sometimes results from a pure relaxation of the mucous membrane of the bowels, permitting the liquid parts of the blood to pass through the walls of the capillaries, almost as through dead membrane. Very frequently inflammation of the mucous coat ends in such a state of debility or relaxation. The vessels, dilated in the active stage of the disease, with pores also probably enlarged so as to admit the passage of the liquor sanguinis, retain this condition upon the cessation of the excitement; and the extravasation and consequent diarrhoea continue long after the occasion for them has ceased. It is under such circumstances that astringents prove most useful in this affection.
Another very frequent occasion for their use in diarrhoea is when the discharge, no matter what may have been its origin, is so profuse as to endanger the safety of the patient. Such is the case in epidemic cholera; and I have repeatedly known patients in danger of their life from copious white alvine evacuations, dependent on portal congestion from inertness of the capillaries of the liver. Here astringents are sometimes indispensable.
In cases of diarrhoea connected with vascular irritation of the mucous membrane, perhaps with some degree of acute inflammation, and very often in chronic inflammation, it may be proper, even though the discharge may not be immediately dangerous by its quantity, to employ astringent medicines, having along with their astringency a sedative or alterative property, which renders them useful in the treatment of the irritation or inflammation itself; and, when a very exhausting discharge, originating in such causes, imperiously demands the employment of astringents, it is to this set of them that we should preferably have recourse. Acetate of lead fa indicated in the more acute of these cases, and sulphate of zinc, sulphate of copper, or alum in the more chronic; the first from its sedative, the three latter from their alterative action upon inflamed surfaces.
Dysentery is another complaint in which astringents are frequently recommended by writers. But a cautious discrimination is here neces-sary, in order to avoid the most serious consequences; and, in ordinary acute dysentery, in the earlier stages, it is I think best to avoid entirely their internal use, even that of acetate of lead, which has been commended by some. In the advanced stages, when the discharges have become more copious, the grade of the inflammatory excitement greatly reduced, and the patient's strength exhausted, they may sometimes be employed with benefit; though, even under such circumstances, caution should always be observed. In the chronic form of the disease they are not unfrequently useful, particularly in warm climates, where there is greater laxity of system, and especially of the bowels, demanding the use of this class of remedies. The metallic alterative astringents are most efficacious in these cases, though the vegetable are also not unfrequently employed.
Other morbid secretory affections, in which the internal use of astringents is called for, are diuresis or excessive secretion of urine, profuse and exhausting sweats, catarrh of the bladder, excessive bronchial secretion, and sometimes possibly dropsical effusion dependent on relaxation of the tissues. In these complaints they are less obviously efficacious than in those of the bowels; because, in the latter, they are brought directly into contact with the diseased tissue, while, in the former, they must reach it through the medium of absorption. A rule in these cases is to select the particular astringent which experience has shown most readily to reach the seat of the discharge. Thus, uva ursi and chimaphila are especially useful in the affections of the urinary passages, from their well-known quality of impregnating the urine.
Hemorrhages often demand the use of astringents; and the general rules before given hold, in relation to this set of discharges, as well as to morbid secretions and exhalations. When active, and connected with plethora or local vascular irritation, unless alarming by their quantity, or injurious by their position, they should be treated hesitatingly with astringents; and, should this class of remedies be indispensable, those should be selected which are sedative as well as styptic, such as cold, and the preparations of lead. After the relief of the plethora Of congestion, and a sufficient reduction of the active character of the hemorrhage, either by depletory measures, or in the course of the complaint, astringents may be employed without hesitation, and without any speacial reference to their antiphlogistic properties. In passive hemorrhages no particular caution is requisite; the free use of astringents being almost always indicated in these. Besides the mere property of closing the bleeding orifices, it is probable that many of the astringents exercise another power in arresting hemorrhage; that, namely, of increasing the coagulability and plasticity of the blood.
In most instances morbid relaxation is attended with morbid discharge, and the two indications are answered at the same time. But occasionally there is an unhealthy laxity of the non-secreting tissues; and even the secreting may be Affected in the same way without increased extravasation. In scrofulous diseases, and other cachectic affections dependent on defective or depraved nutrition, this condition is not uncommon; and astringents have accordingly been much and advantageously used in their treatment. In the convalescence from febrile and other acute diseases, especially when somewhat protracted, the same condition not unfrequently exists, calling for the same remedies. It is probable that sulphuric acid and the chalybeatos, so much employed under these circumstances, may prove useful as well by their astringent as their tonic virtues. In chronic inflammation of the mucous membrane of the stomach and bowels, when all acuteness is passed, and the blood-vessels are merely passively distended, or ulcerations exist, which, in consequence of the laxity and feebleness of the tissue, are unable to take on the healing process, there would appear to be an indication for astringency; and the fact is, that, among the most efficient remedies in such affections, are some of the mineral substances belonging to this class, as sulphate of iron and sulphate of copper.
The indication for astringents in the early stage of inflammation, founded on their property of contracting the vessels, and thus excluding, in some measure, the blood necessary for the support of the inflammatory process, can seldom be fulfilled by their internal use. To answer this purpose, they must be brought to act upon the inflamed vessels in a more concentrated state than would be safe, or indeed possible, in the blood, through the medium of absorption; and they would consequently be wholly inapplicable to any inflammatory affection, the seat of which could be reached only through the circulation. Even in inflammations of the alimentary canal, there would be too much risk that, if used largely enough to have any powerful effect, they might act more disadvantageously as irritants to the sound parts, than usefully as astringents upon those inflamed, as it would be impossible to limit their application to the latter; and, besides, there is always difficulty in deciding, whether the inflammation has not passed the point at which any good could be expected from them. Hence, the astringents can seldom be used internally, with the view of rendering commencing inflammation abortive; and it is only externally or topically, that, as a genera] rule, they can be beneficially applied upon this principle.