Triazoles are special chemical compounds characterized by a ring-shaped structure. All triazoles always have the chemical molecular formula C2H3N3. This formula indicates that triazoles are composed of five atoms. Each individual molecule consists of two carbon atoms and three nitrogen atoms.
What are triazoles?
Triazoles are usually aromatic compounds that are heterocyclic and consist of a five-atom ring. This ring is composed of carbon and nitrogen atoms. From a chemical point of view, triazoles exist in two different isomeric forms. On the one hand there are the so-called 1,2,3-triazoles, on the other hand the 1,2,4-triazoles. Depending on how the nitrogen atoms in the triazole are arranged in the heteroaromatic five-membered ring, two isomeric triazoles exist. These exist in two so-called tautomeric forms. The only difference between these forms is the localization of the nitrogen atom within the ring. A hydrogen atom in turn bonds to this nitrogen atom. Basically, it should be noted that 1,2,3-triazoles can exist in two different tautomeric forms, the 1H-1,2,3-triazoles or the 2H-1,2,3-triazoles. Similarly, 1,2,4-triazoles exist in both 1H-1,2,4-triazoles and 4H-1,2,4-triazoles. From a pharmacological point of view, triazoles are a separate category within antifungals. Antifungals are special agents that are effective against fungi. The so-called triazole antifungals include, for example, the active ingredients fluconazole, itraconazole, posaconazole, and voriconazole.
Pharmacological action
Basically, triazoles are antifungal agents. Therefore, to understand the mode of action of triazoles, it is essential to take a closer look at the structure of fungi. The cell wall of fungi is composed of so-called polysaccharides and the substance chitin. Chitin is not only found in fungi, but also plays a central role in the structure of insect carapaces. Inside the cell wall of fungi is a cell membrane, the most important part of which consists of the substance ergosterol. In this respect, the cell membranes of fungi differ from human membranes. In human cells, the substance cholesterol is present instead. Fungi produce the important substance ergosterol themselves for the construction of their cell membranes. The production takes place step by step on the basis of the substance squalene. All modern active substances and drugs against fungi attack the formation of the substance ergosterol. Like the triazoles, the imidazoles also inhibit the third stage in the production of ergosterol. To this end, the two active ingredients block the enzyme needed for the conversion. As a result, other building materials are produced instead of ergosterol. These defective substances impair the metabolic processes required for fungal reproduction. Therefore, the triazoles are said to have a fungistatic or reproduction-inhibiting effect. Certain triazoles lead to the fact that the building materials of the mushrooms are strongly changed. This means that the fungal membranes can no longer be built up properly. As a result, the cell interior leaks out, leading to the death of the fungus. For this reason, some triazoles also have a fungicidal or killing effect. A typical representative of this group, the active ingredient fluconazole, has a fungistatic effect at therapeutic doses in most cases. However, at higher doses, it also shows fungicidal effects in some organisms. The substance interferes with the conversion process of lanosterol into the molecule ergosterol. As a result, defects occur in the cell membranes of the fungal cells. In human cells, on the other hand, the effect of fluconazole is much weaker. In principle, fluconazole is characterized by a relatively broad spectrum of activity. Primarily, the substance is effective against pathogenic fungi, for example, Candida, Epidermophyton, Histoplasma capsulatum, Cryptococcus neoformans or Microsporum.
Medical application and use
Triazoles are used in many different applications. Numerous derivatives are used as drugs, especially as antifungals. Commonly used drugs include fluconazole and itraconazole. In addition to a use in medicine, triazoles are also used, for example, as pesticides.Here, too, they benefit from their fungicidal action. Typical agents include, for example, cyproconazole, epoxiconazole, hexaconazole, tebuconazole and triadimenol. There exist some plant diseases for the control of which only triazoles may be used. Within the scope of medical use of triazole antifungals, both local and systemic application is possible. However, antifungal agents that are applied systemically require close attention to the possible side effects. The antifungal agent fluconazole, for example, is used in both topical and systemic therapy of various fungal infections, such as mucosal candidiasis, systemic fungal infections, and severe mucocutaneous fungal infections.
Risks and side effects
Several potential side effects and discomforts are possible in the course of therapy with triazoles, which vary depending on the individual case. For example, nausea and vomiting and itching of the skin sometimes occur. In addition, liver function disorders sometimes occur. In addition, the urine sometimes becomes discolored during treatment. If side effects or other complaints occur during or after therapy with triazoles, a physician should be consulted immediately and the drug discontinued if necessary.
