Deodorant

The first European deodorants relied on strong perfumes to mask body odor. When it was realized that the source of the odor was the microbial breakdown of triglycerides of fatty acids such as propionic, butyric, and hexanoic acid, antimicrobial products were introduced. One early formula even contained 1% formaldehyde!

The use of aluminum salts to reduce perspiration appears to predate the use of antimicrobials; although used primarily to reduce wetness, they also lessen the feedstock for bacterial breakdown, and they are now known to have recognizable antimicrobial properties. With the development of antiperspirant materials restricted by legislation in Europe and the USA, formulation improvements have been aimed at enhancing the activity of permitted aluminum salts and aluminum-zirconium complexes, improving product texture and aesthetic appeal, and reducing residual whiteness.

The major manufacturers of antiperspirant actives are constantly striving to improve the material's activity within the parameters that further studies concerning the polymer distribution and molecular size of aluminum and aluminum-zirconium systems have been correlated to clinical efficacy studies to determine the optimum distribution for enhanced efficacy.

Other materials for which the suppliers claim deodorant properties include Ethylhexylglycerin, which is said to inhibit the growth of odor-causing bacteria while at the same time not affecting the natural skin flora, and a lactate ester. Data shows that di-C12-13 alkyl lactate has no inhibitory action against bacteria but significantly reduces underarm odor. Suppliers believe that the absence of odor is due to the bacterial enzymes preferentially breaking down the ester rather than the triglycerides of human lipids. The material is suggested as a replacement for antimicrobial compounds in deodorant sprays, lotions, and creams, as an additive to antiperspirants to enhance activity, and, because it is compatible with surfactant systems, it is suitable for shower gels and body washes, making a deodorant claim.

The effectiveness of copper and zinc salts in reducing body odor is now thought to be because they inhibit the development of bacterial enzymes that cause malodor. A solution of zinc citrate in propylene glycol citrate has astringent and deodorant properties. Neither have bactericidal or fungicidal properties; zinc salts chemically combine with the bacterial decomposition products of perspiration, thus inhibiting odor development.