Merbromin is an antiseptic used in cases of minor cuts and scrapes. It is also used in experimental biology to stain biological samples. It is an organo-mercuric disodium salt compound and hence is also marketed as mercurochrome (highlighting its capability to stain and a compound containing mercury), merbromine, mercurocol, sodium mercurescin, asceptichrome, supercrome, brocasept and cinfacromin. Although it is readily available in most countries because of its mercury content it is no longer sold in Switzerland, United States, France, Iran, Germany, Brazil, and Australia.
The Merbromin Solution
Merbromin or merbromin solution is widely marketed as mercurochrome, where the suffix “mercuro” is for its mercury content and “chrome” is for its colouring properties. The merbromin solution is generally used even as an over-the-counter antiseptic solution, in which it is typically present at 2% concentration dissolved in ethyl alcohol (tincture) or water (aqueous). The ethyl alcohol solution also works as an inhibitor for the growth of microorganisms or infectious agents that would otherwise occur near the cut or scrape sites leading to it being one of the easily affordable antiseptics as the merbromin solution price is quite low and can be taken over the counter easily.
Merbromin was discovered for its antiseptic properties by physician Hugh H. Young at the John Hopkins Hospital in 1918. The principal reason that merbromin uses mercury for disinfection is that it disrupts the metabolism of a microorganism and kills it. Later on, the antiseptic utility of the merbromin solution became so popular that it was used for all types of minor injuries and so common in day-to-day life as the first approach solution to treat schoolyard injuries in kids as well. Until 1998, it fell under the category of “generally recognised as safe” drugs or solutions classified for the general purpose by the FDA. But because of its mercury content and on the citation that it can lead to mercury poisoning, in 1998, FDA reclassified it under the “untested” category and since then the distribution was halted at least of the general purpose use of merbromin solution. This was followed by a halt in sales in Brazil (2001), Germany (2003), and France (2006). But it is readily available in most other countries.
For the synthesis of merbromin, dibromofluorescein is combined with mercuric acetate and sodium hydroxide. Another way of synthesizing merbromin is by the action of mercuric acetate only on or in combination with sodium dibromofluorescein. Its prominent chemical properties include its anionic character which can be understood from the structure given below:
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Because of the anionic character of merbromin, it cannot be mixed with a majority of alkaloid salts and most local anaesthetics as they are acidic in nature and such mixing will result in dangerous exothermic reactions releasing toxic gases or aggravating a non-fatal injury into a serious one. Therefore, it is available in the market in a mixture of ethyl alcohol and aqueous water.
The widely accepted and best-known merbromin solution uses is an antiseptic for the treatment of minor wounds, burns, and scratches. Due to similar utilities, it is also used in the antisepsis of the umbilical cord and the antisepsis of the wounds with the inhibited scar formation, such as neuropathic ulcers and diabetic foot sores. Merbromin is also known for the staining of biological samples. When it is applied to a wound, the skin is stained with a distinctive carmine red colour. The stain persists for up to two weeks and is removed by repeated washings. Another common merbromin solution uses includes its activity on infections or toenails because of the permanence and lethality to bacteria.
Scientifically, merbromin is also used in experimentation for the staining of biological samples. It is used as a biological dye for marking the tissue margins. In order to detect metal fractures, merbromin solution uses include its use as a metal dye in industrial dye penetrant inspection.