IODIN FUMES
One of the important factors connected with therapeutics as a science is the method of administration of medicinal substances. Drugs may be given by mouth, by hypodermic or intravenous injection, by inhalation, by inunction or, less frequently, by the use of other entrances into the body. In choosing a method, the physical characters of the substance to be administered and the immediate effects of the substance on the body tissues with which it may come in contact must be especially taken into consideration.
These factors apply particularly in the case of substances like iodin, arsenic, mercury or the biologic products in which the mode of administration radically modifies the action. For some time, manufacturers have urged substitutes for tincture of iodin, claiming that their substitutes were free from the undesirable properties of the tincture, and, at the same time, possessed special virtues which the tincture could not possess. More recently, attention has been directed to the administration of iodin in the form of vapor. The diffusing and penetrating powers of gases have particularly attracted the attention of therapeutists, since by this method drugs may be applied to rather inaccessible portions of the body, such as the lining of the lungs, the throat and the mucous membranes of the genito-urinary tract. Furthermore, it has been asserted that iodin in the form of fumes has increased combining powers, and is thus far more potent in effect than iodin administered by any other route. There do not seem to have been any adequate scientific investigations of the subject, however, until the recently published results of Luckhardt and his collaborators[293] at the University of Chicago. In their experiments, both on man and on animals, accurately determined quantities of iodin were vaporized in a special device, and the fumes applied to the skin. At the same time, the tincture was applied to the skin of other persons as a control. Iodin was also applied to the skin of dogs with hyperplastic thyroid glands; and the effects on the gland, before and after administration, studied. Dogs were also used to determine whether iodin fumes were absorbed from the lungs. As a result of these investigations, which are reported in great detail, it was found that iodin, when deposited on the skin in the form of fumes, is absorbed. More iodin was recovered from the urine, following the application of the tincture, than was recovered following the use of the fumes. This result is explained by the authors on the ground that probably more iodin was actually applied, and that the iodin so deposited was held in combination with the protein during the process of coagulation of the latter by the alcohol of the tincture, leading to a state of continuous absorption. It is probable, furthermore, that the iodin deposited on the skin in the form of fumes is revaporized to some extent by the heat of the body.
Most important were the effects of iodin administered intratracheally in the forms of fumes. Iodin given in this way seems to be rapidly and completely absorbed; but it was found that the administration of the fumes of iodin by inhalation through the respiratory passages, even in small quantities, is fraught with great danger. Such administration induces dyspnea; and when it is given in large quantities, acute and fatal pulmonary edema ensues within twenty-four hours. When respiratory disorders are present at the time of administration, the fatal edema supervenes very quickly. Thus far, no device designed to deliver fumes controls the dosage.
It is interesting to consider, as do the authors, the fact that the fumes of iodin have the same effect as those of two other halogens, bromin and chlorin. The results of these experiments with iodin fumes on the dog, as shown by necropsy findings, are practically identical with those reported by military surgeons as found in soldiers gassed with chlorin during the war.
The results of these researches are additional evidence as to how scientific research may confirm or deny conclusions based on empiric therapeutic observations. The work may well serve as a model for similar experiments, now being made, on the therapeutic use, intravenously, of such substances as nonspecific proteins or organic preparations of toxic drugs. The patient should at least have the chance that is afford him by preliminary experiments, scientifically performed on animals in the research laboratory.—(Editorial from The Journal A.M.A., May 29, 1920.)