The Action of Medicines in the System / Or, on the mode in which therapeutic agents introduced into the stomach produce their peculiar effects on the animal economy

by Frederick William Headland

The kidneys generally constitute the channel by which these Catalytics are removed from the blood. Most of them, in passing out, act as diuretics. To this we must, perhaps, except the salts of lead, zinc, and copper. Doubtless some are excreted partially or entirely by the mucous membrane of the bowels, but this we cannot so readily appreciate. The circumstance that the astringents just mentioned are efficacious in diarrhœa seems to point to their access to the intestinal surface from the blood.

It has already been shown that these Catalytics are all soluble in some way in the intestinal canal, and that they are absorbed. (Vide Prop. I.; Prop. II.) All of them that can be detected by chemical means, have actually been discovered in the blood. But the system will not, if it can be avoided, suffer them to remain there long. The glands are charged with the office of purging the blood of all morbid materials; and thus these substances pass out in the secretions; most particularly, as I have just said, in the secretion of urine.

Every one of the medicines of this division, enumerated above,—excepting Colchicum and Pitch, which are difficult to recognise chemically,—have been detected in the urine by M. Wöhler, M. Orfila, and others. The Alkalies and Acids are combined, so as to form salts; the vegetable salts are decomposed; Sulphur has changed into Sulphuric acid; and the metallic bases are found to be variously combined; but all the fixed inorganic materials remain essentially the same, however altered in arrangement. Many of these medicines have been likewise detected in the secretions of other glands. This subject will be further discussed in the consideration of Prop. X., and does not immediately concern us now.

Thus the minor propositions may be considered as proved; and all that I have ventured to affirm of this group of medicines is, that they counteract morbid agencies by an operation in the blood.

Now the mode of counteraction is not defined, because it is only in a few cases that we can even guess at it. In the majority of instances it seems inexplicable. We know that Syphilis is a poison in the blood. Mercury also is a poison in the blood. But why does Mercury antagonize and annihilate Syphilis? The case is the same with Scrofula and Iodine; with Lepra and Arsenic. It is very humiliating to be baffled when we have got thus far; when, led by the hand of Science, we have been conducted almost to the end of this interesting inquiry, to find that we are perfectly unable to take the last step, and thus to conclude our adventure.

When there is no disease, a Catalytic medicine may work out its own action in the blood, and produce a disease. But when there is some previous disorder, the working of the Catalytic may operate so as to counteract this already existing action, being so far similar to it, that it acts in the same department, and may thus occasionally produce by an accident like results; but being, nevertheless, as we have seen, essentially contrary to it, because it neutralizes it.

Such opposite relations are met with even among natural diseases. Vaccination and Small Pox afford us an instance of the mutual counteraction of morbid processes. These poisons are alike in their operation. Dr. Fouquet, of Freiburg, has tried the effects of re-vaccination in Syphilis, on the inmates of a large military hospital, with great apparent benefit, as it is said. These poisons are unlike in their results. So are Ague and Phthisis; and persons who have had Ague are said to be less liable to Phthisis than others. Again, we find that one attack of an eruptive fever preserves the system in some way from the renewed operation of the same poison. In these morbid phenomena we find something of a parallel to the curious operation of Catalytic medicines in controlling blood-diseases; for I have shown that these remedies themselves are artificial blood-diseases.

Such ideas lead us on into the uncertain regions of speculation.

The idea that diseased actions may possibly be accounted for by supposing the existence of special fermentations in the blood, is by no means a new one. Inscrutable as these diseased actions themselves may be, yet, we are enabled to recognise processes of a nature analogous to fermentation as going on in that fluid in health. Of such a kind probably are, the change of albumen into fibrine; the changes which take place in the starchy matters of the food before they can be oxidized into carbonic acid; and the changes that must occur in nitrogenous substances before absorption, as well as those that accompany afterwards the downward progress of the same materials, from living tissue into Urea and Uric acid, to be finally excreted from the system. It is a curious fact that nearly every known product of organic fermentation has been discovered in the human body in health or in disease. Lactic, butyric, and acetic acids, have been frequently found there. Dr. Heintz has lately added to these succinic acid, discovered in a hydatid cyst of the liver.

The production of many disorders by the access of a known morbid material, the working of that material on the particles of the blood after a special fashion peculiar to itself alone, and the gradual elimination of certain products, also peculiar to this one operation, are circumstances in which diseases bear an obvious analogy to processes of fermentation. The same remark applies to the working of Catalytic medicines.