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J. Soc. Cosmet. Chem. 24 259-278 (1973) ¸ 1973 Society of Cosmetic Chemists of Great Britain Some observations on the formulation 'and properties of chlorhexidine N. SENIOR* Presented on the 11th April 1972 in Oxford, at the Symposium on 'Skin--Environmental responses and protection', organized by the Society of Cosmetic Chemists of Great Britain. Synopsis--The selection of the most appropriate salts of the ANTISEPTIC CHLORHEXIDINE and the influence of formulation adjuncts on drug availability are discussed. The rapid, broad spectrum bactericidal action in association with the wide safety margin, freedom from SENSITIZATION and drug resistance risks are factors influencing its current wide usage in medical and surgical practice. Hospital applications include bactericidal handwashing, pre- operative SKIN disinfection, prevention of cross-infection and the DISINFECTION of inanimate objects. Chlorhexidine is employed advantageously in antibacterial TOILET PREPARATIONS and its properties are ideal for safe and effective DEODORANT compositions. In DENTAL applications it is adsorbed on the enamel, plaque and mucins and accordingly it may be valuable in the prevention or treatment of oral infections and in the control of dental caries. INTRODUCTION Chlorhexidine, 1,6-di-(4-chlorophenyldiguanido)hexane, was first synthesized by Rose and Swain (1) who, with the guidance of Davies, Francis and Martin (2), selected it from a series of bisbiguanides possessing marked bactericidal action against a wide range of micro-organisms (2). Since this work, which took place in the early 1950s, there have been many publications on its medical and veterinary applications and there *Imperial Chemical Industries Ltd (Pharmaceuticals Division), Macclesfield, Cheshire. 259