Antiseptics

ANTISEPTICS (from Greek anti- against and sepsis-putrefaction). Antiseptic is the name given to an action on microbes that retards their development, while disinfecting is the name given to an action that kills them. However, usually the name Antiseptics is given to all substances that act destructively on pathogenic microbes, since the same substance can be both antiseptic and disinfecting, depending on concentration. The latter is the main condition allowing the application of these substances on a living organism, because they represent general cellular poisons and only in sufficiently low concentrations can be carried by tissue cells without noticeable harm. The therapeutic value of Antiseptics depends, on the one hand, on the strength of its disinfecting (resp. antiseptic) action, and on the other on the degree of its toxicity, characterized by the minimum lethal dose per kg of animal weight (dog, cat, rabbit): the greater the former and the smaller the latter, the higher the therapeutic value of the agent. For a comparative evaluation of Antiseptics it is convenient to use the therapeutic index, which represents the ratio of the antiseptically acting (therapeutic) dose of the substance to the minimum lethal dose; the smaller the numerical value of this fraction, the higher the therapeutic value of the substance. For the general disinfection of the organism the only condition allowing the application of Antiseptics in a therapeutically effective quantity is its sufficiently low toxicity, and therefore since the first works of Ehrlich the task of experimental chemotherapy has been to obtain such chemical compounds by means of which actual disinfection of the organism is achieved without causing it harm, i.e., compounds which would possess high parasitotropism at low organotropism. To the group of substances applied for the general disinfection of the organism belong almost exclusively Antiseptics of specific etiotropic action, such as mercury preparations, bismuth, arsenic, quinine, probably salicylic acid and some dyeing substances. To this same group belong also Antiseptics of nonspecific action in the form of colloidal metals, chiefly silver and gold, but their action is much weaker; some completely deny the possibility of general disinfection by means of colloidal metals; the therapeutic effect obtained with their application is often attributed not to their antiseptic action but to the stimulating mobilization by the organism of its defensive means, as happens in nonspecific protein therapy. For the action on the urinary and genital tracts, Antiseptics are administered per os by such substances which, containing Antiseptics in a bound state or passing into such after absorption from the intestine, detach this active principle under the influence of the activity of the renal parenchyma. Such are the glucoside arbutin contained in the leaves of Uvae ursi, which is split in the kidneys with the excretion of free hydroquinone, or certain essential oils which, after passing into harmless combinations with sulfuric and glucuronic acids after absorption, are again transformed in the kidneys into antiseptically active principles. To resorptively acting substances applied for some, as yet unproven, disinfection of the respiratory organs belong creosote, with its active principle guaiacol, its derivatives, certain essential oils, etc. The harmful resorptive action of Antiseptics is reflected on the central nervous system, various departments of which are paralyzed by them (often after a stage of excitement), and on the excretory organs where they can act in a higher concentration than in the blood after absorption. This danger of Antiseptics is not excluded even with their local application on mucous membranes and wounds, from where they can be absorbed and cause signs of poisoning, especially those which dissolve in lipoids and are more easily absorbed, such as corrosive sublimate or phenol, etc. The quantity of various Antiseptics is very great, and they represent compounds of diverse chemical nature. Antiseptics can be divided into two main classes: 1) inorganic compounds: ozone, hydrogen peroxide, halogens, alkalis, acids, metals, metal salts; 2) organic compounds: saturated hydrocarbons, their substituted and derivative, polymethylene and terpene hydrocarbon derivatives, benzene hydrocarbons and their derivatives, naphthalene and its derivatives, anthracene derivatives, heterocyclic compounds. The mechanism of action of Antiseptics in many cases can be linked to their chemical or physicochemical properties. Thus, alkalis, acids, and salts of heavy metals denature plasma proteins, the first acting with their hydroxyl ion, the second with the hydrogen ion, the third with the metal ion. In some substances their effect belongs to the action of the antiseptic principle detached from their molecule; in strong oxidizers (ozone, hydrogen peroxide) to active O acting on anaerobic and aerobic microbes; in iodoform the action belongs to the atom of iodine; in chloramine T, dichloramine G, and Dakin's solution to the atom of chlorine. In other cases Antiseptics act with the whole undissociated molecule. Recently introduced into therapeutic practice are some dyeing substances - derivatives of aniline and acridine, or dibenzopyridine: methylene blue, tripan-rot, scarlet-rot, trypanflavin, rivanol, etc. These substances seem to possess a certain specificity: all of them act more strongly on Protozoa than on bacteria, tripan-rot in trypanosomiasis and piroplasmosis, methylene blue in malaria. Antiseptics of the group of cupreine derivatives, representing quinine in which the methoxy group is replaced by a hydroxyl group, possess an even more specific action and also strengthened in the presence of blood serum: thus, optochin, or ethylhydrocuprein, acts on pneumococci; eucupin, or isopropylhydrocuprein, on streptococci, meningococci, and gas gangrene bacilli; vucin, or isooctylhydrocuprein, on streptococci and staphylococci. However, these substances also possess strong organotropism and so far cannot find therapeutic application outside the field of laboratory-clinical research.