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.
In fulfilling this indication, astringents act by contracting the pores in the blood-vessels through which the discharge takes place. Two distinct kinds of morbid discharges are affected by them; the one consisting in excessive or deranged secretion or exhalation, the second in hemorrhage. In reference to their influence in checking the latter, the astringents are denominated styptics. In both, some cautions are required in their use.
When the discharge depends upon some local or general disorder which it is intended to relieve, as plethora, active congestion, inflammation, or the presence of noxious matters in the blood, the astringents are as a general rule contraindicated; and the same remark applies to what have been denominated critical discharges; though, strictly speaking, these belong in fact to one of the preceding categories. As the astringents operate in general by merely closing the avenues by which the fluid escapes, and have no effect in removing the disorder which the discharge is intended to relieve, it is obvious that they may, under these circumstances, do much mischief. If they check the discharge, they may increase the real pathological condition; if they fail, their own irritative effect is superadded to that previously existing.
Again, a discharge, though originally morbid, may have become habitual; and the processes of digestion and sanguification having taken on increased activity, the system may have accommodated itself to the drain. Astringents in such cases might disturb this balance, and give rise to dangerous local congestion, or general plethora. If resorted to, therefore, they should be applied cautiously and gradually, so as to permit the system to accommodate itself to the change; or the apprehended evil should be counteracted by other measures, as by cathartics, issues or setons, a regulated diet, and increased exercise, which may have the effect of consuming the excess of blood.
Astringents are applicable when the discharge is purely local, and dependent on no coexisting disease; as, for example, in the hemorrhage consequent upon an accidental rupture of a blood-vessel, either from direct violence, or from a sudden and temporary congestion produced by straining, position, etc.
They are also applicable when the affection depends upon debility or relaxation of the coats of the blood-vessels, either original, or consequent upon previous excessive excitement, which has quite disappeared. This is a very common condition in the advanced stages of inflammation; and it is. perhaps, under such circumstances that astringents are upon the whole most useful.
Another condition which sometimes imperiously calls for them, even under otherwise opposing indications, is when the discharge is so copious as itself to become the main source of danger. Thus, a hemorrhage-from the rectum, intended as a relief to serious plethora or portal congestion, may be so frequent or abundant as to put life at risk; and, in this case, should be arrested without hesitation. It is not unfrequently necessary to choose between such opposite indications; and the prudent practitioner will always prefer what may seem to him the least of the two evils.
The position, moreover, of the discharge may sometimes be such as to render this the greatest danger; as in a case of hemoptysis which threatens to overwhelm the lungs. Here astringents may be employed, though the hemorrhage might have been the result of a congestion, and may have a tendency to relieve it. In such cases, however, the use of the styptics should be accompanied with measures, calculated, in a safer way, to accomplish the end for which the hemorrhage was intended.
Finally, there are certain individuals of this class which, with their astringent property, unite others calculated to relieve the affection in which the discharge originated, and against which, therefore, the contra-indication above mentioned has less force than against the members of the class generally. Thus, acetate of lead, while powerfully astringent, is also antiphlogistic, and may sometimes be advantageously employed to arrest morbid secretion from inflamed surfaces, when others would prove only injurious.
It is unnecessary to detail minutely all the diseases in which astringents may be useful, and the circumstances in each, which modify the indication for their employment. Guided by the above principles, the practitioner will judge for himself when the occasion may be offered. It will be sufficient, for the sake of illustration, to trace a single disease through its various therapeutical relations with astringents, in conformity with the foregoing rules, and afterwards simply to enumerate the other diseases in which they may be required, to meet the indication now in view.
Diarrhoea is one of the complaints in which astringents art: most frequently employed. But this affection often depends on inflammation of the bowels, or congestion of the liver and whole portal circulation, which it has the purpose and effect of relieving. Astringents, if they succeed in checking the increased secretion, which is at once the agent of relief, and the cause of the diarrhoea, will act injuriously on the inflammation or congestion; if they fail, they will add their own irritation to that preexisting. They are, therefore, as a general rule, improper under such circumstances. In certain kidney affections, urea accumulates in the blood, and sometimes seeks an outlet through the bowels, producing diarrhoea, which thus protects the system, in some measure, against the fatal influence of that agent upon the brain. Diarrhoea is sometimes critical; that is, occurs at the termination of certain diseases, such as •idiopathic fever, and is probably one of the processes by which the system relieves itself of its morbid condition. In either of these cases, astringents might do serious injury. Lastly, the diarrhoea may have existed so long that the system has accommodated itself to the increased discharge, the sudden checking of which might occasion dangerous congestion of the liver, lungs, or brain, or perhaps dropsical effusion. Here, though astringents may not be altogether contraindicated, they should be used with caution, so as gradually to bring about the cure of the complaint; while, in the mean time, measures may be taken to obviate any threatened injury.