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 following is the arrangement of the subject which I have thought it best to adopt. We will, in the first place, consider some of the statements ventured by authors respecting this kind of medicines: as a comparison of these should aid us in the discovery of the truth. In the second place, it will be convenient to enumerate the medicines contained in the orders named above, and to proceed to prove the minor propositions of Catalytics taken altogether. A considerable amount of difficulty attaches to this consideration; and, as the argument which applies to one order will apply to all, much unnecessary repetition will be avoided by this plan. In the third place I must conclude by making some remarks on each of the orders in succession. To proceed now to the first of these topics.

In referring to the opinions that have been advanced on the action of this group of medicines, our task is rendered comparatively easy by the fact that a great number of writers on Materia Medica have failed to recognise them collectively. It may seem strange to one who has reflected on the subject, but it is nevertheless true, that the majority of authors have taken no notice whatever of medicines acting in the blood, with the exception of Acids and Alkalies, which are grouped by some as chemical remedies. All other medicines have been generally arranged under the two great and ill-defined heads of Nerve-medicines and Eliminatives. I cannot find it possible, by either of these terms, to give any idea of the real action of the many important agents which I have included in this division.

It would seem that it has been generally supposed that medicines,—bodies of active properties, and more or less peculiar construction,—are able to enter and to pass through a fluid which is still more complicated and changeable in nature than themselves, yet that while so doing they produce no impression upon it, but proceed passively to the solid tissues, or quietly pass out of the body, without ever leaving behind them any trace of their action.

Certain writers have made some amends by including in their arrangements a class termed Alteratives. But even then they have not unfrequently laid it down as a rule that they produce, in the first place, an impression on the nervous system, and that this has subsequently the effect of altering the manifestations of vital force. How varied and peculiar in nature must these nervous impressions be, to account for actions which are often so widely different!

The medicines thus grouped as Alteratives correspond very nearly with my division of Catalytics. The permanency of their effects, and the fact that the disorders which they cure are blood-disorders, will sufficiently stamp the character of the operation of these remedies.

In many works, as in those of Dr. Duncan, of Dr. A. T. Thomson, and more lately, of Drs. Ballard and Garrod, the existence of a class of Alteratives or blood-medicines is not even recognised or alluded to.

But in the learned classification of Dr. Pereira blood-medicines hold an important place. All except Chalybeates are grouped together in a sub-class, called Spanæmics, because they tend to impoverish the blood. In addition to those which I have named Catalytics, there are here the acids and alkalies. It is true that all these medicines, after long use, impoverish the blood, which, indeed, suffices to prove my first point, viz,: that they act in the blood, and that their effect is permanent. But Dr. Pereira has founded his classification on the physiological action of medicines, and not on their therapeutical uses, which form the basis of mine. Thus he takes no notice of the questions of what their ultimate destination may be, or what their primary modus operandi, whether they have to remain in the blood, or to pass out of it, and whether they can act by supplying a material to it, or by neutralizing a material in it. The subsequent statements which Dr. Pereira has chosen as the basis of his subdivisions, founded often on therapeutical action, seem in certain cases to be somewhat problematical. Thus he calls Acids "adipsa," or thirst-quenching, which very imperfectly expresses their action. Alkalies are grouped with Salts, Iodine, and Sulphur, under the general title of "resolventia seu liquefacientia," i.e. resolvents, or liquefacients, which involves an assumption that some might be inclined to dispute. The title of Spanæmics, applied to the whole, though unobjectionable in a classification which is founded upon their ultimate action in health, would be quite inappropriate in an arrangement like mine, which has to do with their influence in the cure of diseases. For our object in making use of such agents is not to impoverish the blood, but to obtain such a manifestation of their power as shall suffice to neutralize the noxious agent, and no more.

Dr. A. Billing (Principles of Medicine, 5th edit. pp. 70-75) considers that Mercury, Arsenic, Colchicum, and all the medicines which have been called Specifics, are not in fact so, but that they are capable of subduing different kinds of inflammation by causing contraction of the dilated capillary vessels. This explanation has certainly the charm of simplicity, but not, in my opinion, the merit of truth. Dr. Billing supports his argument by instancing the number of remedies that have been used in Syphilis, and considers that they must all operate in a similar way, both in this and in other disorders. Yet are all these medicines of use or advantage in Ague, in Lepra, in Chorea, and in Scrofula? But why is it not so, if all act in the same way? Their several actions should exhibit no difference in kind, but only in degree. It is the opinion of the same able authority that Mercury and Iodine diminish morbid growths by starving them; that they cut off the supply of blood by contracting the capillaries in the same way as in other cases. But why then can we not thus remove a fatty tumour, a true exostosis, or a malignant growth? We are seldom able by such means to reduce the size of a tumour, unless it depends on a blood-disorder, as Syphilis or Scrofula. The wide distinctions and the shades of difference which exist between the operations of these several medicines are surely too many and too serious to allow us to account for them all by one explanation.

But we may put aside general arguments, and appeal to facts. In the first place, it is very far from being proved that in all these disorders the capillary vessels are dilated. But let us even admit that it is so proved, and we are not then nearer to the establishment of the above hypothesis. For is the action of any medicinal agent on the capillaries constant in character?