Products and production
Gentian violet solutions are not commercially available as human medicines in many countries and must be prepared for customers in a pharmacy or drugstore. They can also order the solution from specialized suppliers (e.g., Hänseler). According to the New Formulary (NRF), the pure substance methylrosanilinium chloride PhEur should be used (see below), which is available in pharmacopoeia quality from Dynapharm, for example. A gentianaviolet solution can be prepared by dissolving the active substance in purified water. Appropriate manufacturing instructions can be found in the DMS and NRF. Ethanol may be added as an excipient to improve solubility. Gentian violet solutions are available without a doctor’s prescription because Swissmedic classifies gentian violet in dispensing category D. Caution: gentian violet solutions are also on the market in technical quality, e.g., as reagents, which are not intended to be used as medicinal products!
Structure and properties
Different definitions are available. In a broader sense, gentian violet is a mixture of structurally similar triphenylmethane dyes. One of these components is crystal violet, which is officially known as methylrosanilinium chloride (C25H30ClN3, Mr = 408.0 g/mol) and resembles fuchsin (= rosanilinium chloride). In the strict sense, it is exclusively hexamethyl–rosanilinium chloride (Figure, 6 methyl groups). The other components differ in -methylation and are also called methyl violet. In pharmacy today, gentian violet is usually equated with methylrosanilinium chloride, for example by the European or American Pharmacopoeia. According to the PhEur, methylrosanilinium chloride may contain up to 10% pentamethyl–rosanilinium chloride (5 methyl groups). Gentianaviolet is odorless and is present as a powder or in the form of dark green, metallic shiny crystals, sparingly soluble in water and slightly soluble in ethanol 96% and in dichloromethane. Aqueous solutions are dark purple in color.
Effects
Gentian violet (ATC D01AE02) is disinfectant, antibacterial against Gram-positive bacteria (e.g., staphylococci), weaker antibacterial against Gram-negative bacteria, antifungal against yeast (Candida) and dermatophytes, and antiparasitic. It is astringent, protein precipitating, dehydrating and anti-inflammatory.
Indications
In many countries, there are no officially approved indications because no human medicines are approved. Gentian violet is usually used in dermatology in the form of solutions as an extemporaneous formulation for the treatment or prevention of bacterial skin diseases and fungal skin diseases. Among the applications mentioned in the literature are, for example, impetigo, candidamycosis, athlete’s foot, oral thrush, vaginal thrush, vaginosis, boils, staphylococcal and MRSA infections, pressure sores and atopic dermatitis. For staining it is also used in ophthalmology and surgery. It is further used as a veterinary drug, as a staining agent, for skin marking, to prevent transmission of Chagas disease in blood transfusion, in microscopy (Gram stain, histology, nucleic acids) and technically, among others.
Dosage
According to the doctor’s prescription. Usually the solution is applied 1-3 times a day and allowed to dry. Common concentrations used to treat skin infections in adults range from 0.1 to 0.5%. It should be noted that more concentrated solutions are more likely to cause adverse effects (see below). Solutions should be applied carefully to avoid colored stains on other skin sites, the surrounding area, and clothing.
Contraindications
Gentian violet should not be used in case of hypersensitivity, during pregnancy and lactation. Gentian violet solutions should not be closed under occlusion (for example, under a plastic wrap) and should not be ingested. We do not have a complete list of precautions.
Adverse effects
Gentian violet is irritant and may cause skin and mucous membrane irritation when applied locally. Especially in higher concentrations ≥ 1% and in skin folds, skin necrosis and mucosal ulceration may rarely occur. Hypersensitivity reactions have been reported. Gentian violet is a dye, colors the skin, underwear and clothes violet and is cosmetically unattractive.According to Waser/Steinbach, stains can be removed on clothing with soda and bleach and on the skin with alcohol or hydrochloric acid in suitable dilution. The use of gentianaviolet is not undisputed because it shows carcinogenic properties when administered orally in animal studies. Methylrosanilinium chloride is approved by Swissmedic and the FDA for the OTC market and, according to some authors, should be safe for external use. However, we cannot make any conclusive statements regarding safety.
