272 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 93-14•o, 80-17•o and 97-155/o (35). Similar good results were achieved by Mitchell, Slade and Linton (36) using 0.05•o chlorhexidine gluconate in glycerin as a urethral disinfectant and catheter lubricant. Chlorhexidine is a valuable safeguard against infection in obstetrics. Hibitane obstetric cream, a smooth, pourable hand cream containing 1•o of the gluconate, was designed to have lubricative properties to aid the obstetrician in vaginal examinations. It is used in labour for application to the skin on and around the vulva and is practically equivalent to preparing the skin with tincture of iodine. It is nonirritating to the skin and vaginal epithelium and widespread use in midwifery centres has indicated that sensi- tivity reactions are extremely rare. Bacteria applied• to the skin are killed within 15-30 s using Gardner and Seddon's technique (37) and results are of the same order as with 70•o alcohol. Infection and cross-infection in hospitals is kept down by a similar though thicker cream of the same strength but with better cosmetic properties (Hibitane antiseptic cream). It is primarily intended as a prophylactic but it also contains emollients to counteract the adverse effect of repeated immersion of the hands in water. It is used for this purpose by general practitioners as well as hospital staff. A more specialized use of chlorhexidine is for preventing or controlling the nasal carriage of Staphylococci and other organisms. A specially designed cream, nonirritant and pleasant to use (Naseptin) contains the hydro- chloride salt (0.1•o) with neomycin sulphate (0.5•o). This combination of entirely different types of antibacterials provides an effective means of overcoming nasal Staphylococci and minimizes the possibility that bacterial resistance may develop. Carriers are usually constitutionally predisposed to carry these pathogens, especially in the nares, with the result that relapse on recolonization usually occurs in 4-8 weeks after cessation of therapy. The routine twice daily treatment of nurses, patients and newborn infants is followed by a clear-cut reduction in cross-infection according to Rountree et al (38) and subsequent checks have confirmed this observation. The combined use of the nasal cream, and the antiseptic cream on the appro- priate infected areas, is a standard treatment for preventing the spread of furuncles. A salient feature of chlorhexidine in this and all other prophyl- actic uses is the assurance that it deals alike with both Gram-positive and Gram-negative organisms. Whilst chlorhexidine is excellent as a skin disinfectant and as a treat- ment for superficial surface infections, cuts or wounds, it is less successful as a curative agent against more deep-seated infections such as chronic in- fected varicose ulcers. One possible explanation is a failure to penetrate to

FORMULATION AND PROPERTIES OF CHLORHEXIDINE 2?3 the site at which pathogens reside and a contributory factor may be in- activation by pus or tissue debris. TOILET PREPARATIONS At the present time only a minor fraction of the total chlorhexidine out- put is diverted to retail products but this is expected to increase now that it has become fully established in the medical and veterinary fields. Examples of the various applications of the three available salts are: hydro- chloride in Savlon baby powder and Mimospray deodorant (the acetate and gluconate may also be used in sprays) and the gluconate in Savlon baby lotion and in antiseptic solutions such as Savlon liquid antiseptic. In the latter connection there was a problem to convert a colourless, odour- less, chemical into a typical antiseptic solution by incorporating a strong antiseptic perfume, with appropriate colour, a matter which entailed much close attention to the solubilization of essential oils and the conducting of user acceptance trials. In relation to the deodorant field and the rapidly extending market for feminine hygiene products (39), the researches of Morris and Maclaren (40) are noteworthy. These clinicians compared chlorhexidine (0.1•o hydro- chloride) and hexachlorophane (0.2•o) deodorant sprays on 64 women in a cross-over: test on two groups, to the total exclusion of all other antibac- terial preparations. They reported that 'the chlorhexidine spray caused a marked reduction in perineal flora whereas the hexachlorophane spray caused virtually no alteration', concluding that the comparative ineffective- ness of the latter against Gram-negative organisms was a serious dis- advantage. A valuable safety factor with chlorhexidine as a toilet aid is the assurance that significant systemic absorption does not take place. ORAL HYGIENE The main aim of this communication is to survey the circumstances in which chlorhexidine is applied to the skin, its effectiveness and the type of formulations which have been developed. However, an up-to-date appraisal would be incomplete without a reference to the recent researches in the field of oral hygiene. Current oral antiseptic preparations are largely intended for cleansing and deodorizing the mouth and their popularity has risen greatly during the past few years, especially in the U.S.A., though only moderately in the