Pharmacodynamics and Mechanism of Action
Preparations based on Iodum represent a major subgroup of halogen-containing compounds. In medical practice, they are utilized exclusively as antiseptics. It is important to emphasize that despite their high antimicrobial activity, these agents are not used for disinfecting inanimate objects, but are intended solely for the treatment of biological tissues.
The main active principle is free (elemental) iodine. It possesses a universal spectrum of activity, exerting a lethal effect on most known pathogens: bacteria, viruses, pathogenic fungi, and protozoa.
The mechanism of antimicrobial action is based on two key pharmacodynamic effects:
- Protein denaturation. Active iodine has the ability to precipitate and coagulate tissue proteins. During this chemical reaction, specific complex compounds known as iodamines are formed. Coagulation of microbial cell proteins leads to its inevitable death.
- Oxidation. The oxidative properties of elemental iodine additionally provide a potent antimicrobial effect. Among the halogens, iodine is not the most aggressive oxidizer—its oxidation strength is objectively lower than that of free chlorine and bromine.
Alcoholic Iodine Solution (5%) and Rules of Application
The best-known representative of this group is the 5% alcoholic iodine solution. When applied locally to tissues, it demonstrates a pronounced irritant effect. If the concentration of the active substance is high, the irritant effect naturally progresses to a cauterizing effect.
It is precisely because of this pronounced cauterizing effect that the application of this antiseptic in surgical and traumatological practice is strictly regulated. The alcoholic solution is used exclusively for treating wound margins.
Applying the drug directly to the wound surface itself is strictly contraindicated, as contact of active iodine with exposed tissues inevitably causes a chemical burn.
The use of alcoholic solutions carries the risk of local complications. The most common issue is local irritation when treating an extensive surgical field. In some cases, this can lead to a full-thickness chemical skin burn. The risk of such complications increases manifold when high-concentration solutions are used, as well as in patients with sensitive skin.
Aqueous Iodine Solutions (Lugol's Solution)
Since alcoholic solutions are too aggressive for sensitive areas of the body, aqueous iodine solutions are available in the medical arsenal. A classic example of such an antiseptic is Lugol's solution.
Its composition differs fundamentally from alcoholic tincture and includes three components:
- Active elemental iodine.
- Potassium iodide.
- Water.
From a pharmacological classification standpoint, Lugol's solution is also an antiseptic; however, the absence of alcohol makes its action milder. The primary application of this preparation is the local treatment of inflammatory and infectious processes on mucous membranes. In clinical practice, Lugol's solution is traditionally used for the careful swabbing of affected areas of the oropharynx, pharynx, and larynx, ensuring sanitation of the infection focus without the risk of deep tissue damage.