This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This is another agent which has proved very efficacious in numerous superficial disorders, of a nature to be benefited through the protective agency. The tincture of iodine is the preparation usually employed for the purpose, and, in the greater number of cases, will answer very well. When, however, a very strong impression is demanded, the tincture may be saturated, which is easily done by leaving in the bottle a little more iodine than is dissolved. The strength may be made still greater by using iodide of potassium, which increases the solvent power of alcohol as it does of water. Thus, by adding half a drachm of iodide of potassium to a fluidounce of alcohol, it may be made to dissolve a drachm of iodine. A solution of this kind was used by the late Dr. Todd, of London. Some prefer an ethereal solution, of the same strength as the officinal tincture, under the idea that it is less painful; and, as the ether rapidly evaporates, while the alcohol remains for some time to stimulate the surface, there seems to be good reason for the preference. (Durkee, Am. Journ. of Med. Sci , N. S., xxviii. 108.)
A solution in glycerin has recently been employed, as a substitute for the tincture, with asserted advantage. With the aid of iodide of potassium, this solvent will take up a large proportion of iodine. Dr. M. Richter, of Vienna, who recommends this solution, prepares it by dissolving one part of the iodide in two of glycerin, and then adding this to one part of iodine, which is completely dissolved in a few hours. it may be applied by means of a camel's-hair pencil, and should be covered with some impervious tissue, as of oiled silk or gutta-percha, to prevent the evaporation of the iodine. it has the advantage of remaining liquid.
When one of these preparations is applied by a brush to the surface of the skin, it rapidly produces a yellow discoloration of the epidermis, with more or less smarting pain, of which the patient sometimes complains a good deal, but which soon subsides. if the application has been moderate, the stain gradually disappears by the evaporation of the iodine, without any organic change in the cuticle. But such an influence is of little or no effect for the purposes here had in view. The application must be made so as to produce a deep-brown stain of the cuticle, which should be so much affected as afterwards to desquamate. It is often necessary, moreover, to reapply the tincture, and to do so repeatedly, should the evidence of its action on the epidermis diminish. I have often noticed, in erysipelas, while using mucilaginous dressings of slippery elm to the surface, and tincture of iodine to the border of the inflammation, that the stains produced by the latter rapidly disappear under contact with the former; and the inference is that such a contact should be guarded against, in the use of the remedy.
Erysipelas is one of the affections in which iodine has shown the greatest antiphlogistic power. Applied over the whole surface, it will not unfrequently diminish or even subdue the inflammation. But it must be remembered that erysipelas is usually a constitutional affection, and that, if the inflammation is suppressed, the disease is not cured; and there may be danger of the local irritation fixing itself elsewhere, perhaps in some internal organ. it has happened to me to witness a fatal case of such translation; and, though the local application made in that instance was not iodine, yet the principle would be the same with either, and I have, therefore, always avoided any efforts at once to cure the local affection. But when disposed to spread into the head, or too extensively elsewhere, I have very long been in the habit of endeavouring to circumscribe its progress, and keep it within due bounds. For this purpose, iodine is, I think, on the whole the most convenient and effectual means. it should be applied for two or three inches in breadth, partly on the inflamed and partly on the sound surface. When it fails to check the march of the inflammation, it usually moderates its severity. in local erysipelas, arising from wounds, with or without the suspicion of poison, as in dissecting wounds, I have also been in the habit of using tincture of iodine, and, I think, with advantage.
In herpes and eczema, it will sometimes arrest the disease in its early stages; but in the latter affection it will often fail, because the local disease is sustained by a powerful constitutional tendency; and, in many cases, no suppressing agents, however powerful, are capable of subduing it. Herpetic ringworms will frequently yield at once.
The tincture of iodine is also among the most effective means of checking the progress of the variolous eruption. Applied at the first appearance of the eruption, or within a day or two, it will often very considerably modify it, and prevent full maturation and pitting.
But iodine acts also on deeper inflammations. Thus, it may be employed with advantage in inflammation of the absorbents and cellular tissue of the arm or leg, such as occasionally follow wounds of the fingers or toes. it must be liberally applied upon the skin, along the course of the inflamed vessels. it may be similarly employed in inflammation of the absorbent glands.
It has also been strongly recommended in chronic enlargements of the tonsils, applied directly to the mucous membrane covering them.
It is highly useful in inflamed and distended bursae, such as are frequently noticed in rheumatic patients, and, applied freely around the joints, has proved serviceable in similar affections of the synovial membranes. indeed, it may be locally applied, with hope of benefit, in most cases of chronic inflammation and tumefaction of the joints, whether rheumatic, gouty, or scrofulous.
Furuncles, phlegmons in the subcutaneous tissue, and paronychias may be treated in the same way; and corns will sometimes disappear under the application.