J. Soc. Cosmetic Chemists 17 29-44 (1966) ¸ 1966 Society of Cosmetic Chemists of Great Britain Some principles and difficulties of topical treatment in dermatology G. HODGSON* Presented at the Symposium on "Emulsions", organised by the Society of Cosmetic Chemists of Great Britain at Harrogate, Yorks, on $1st March 1965. Synopsis--The majority of dermatological topical treatment is used for alleviation of symptoms. These arise from systemic disease, or a. re just temporary, or longer lasting, individual variations in functions of the skin from the physiological mean. The efficacy of established topical treatments is discussed, including the use of anti-perspirants and detergent ache preparations. Antipruritic agents usually act by anaesthetizing pain fibres or reducing bacterial degradation of protein to polypeptides, which provoke itching. Both local procaine-type anaesthetics and antibiotics, especially the 'mycin' group, are liable to cause sensitization. Topical steroids used under occlusive polythene dressings to increase hydration and permeability in established eczema or psoriasis may cause severe local degeneration of collagen with epidermal thinning, skin stretching ('striae') and bruising, in addition to systemic absorption effects. The treatment of melanosis with bleaching agents, or hydroquinone monobenzyl ether, is clinically and cosmetically unsatisfactory, as is that of depigmentation with methoxy psoralens or disguising agents as dihydroxy acetone. THE CHANGING FACE OF DERMATOLOGY The practice of dermatology does not depend as much as formerly upon topical applications. Those days were without antibiotics, anti- histamines, steroids, and other agents to be effectively administered systemically. These older medicaments were both complex and simple complex because of the polypharmacy of the ingredients, of which few chemists will mourn the passing, and simple because the vehicles had not yet seen the transformation to the more pleasant and effective emulsified and water-washable applications for which we owe so much to the cosmetic industry. *Lecturer in Dermatology, Welsh National School of Medicine, Cardiff. 29

3O JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Unnas' shake lotions are ageless and still used but calamine lotion, like Cinderella, is now transformed under the magic wand of cosmetic emulsifier and colloid mystique, technically described by Wells and Lubowe (1), to parade unrecognized in many creams, liquid face powders, compacts and other make-up preparations of the beauty parlour. New topical applications, however, have not solved many of the problems of treatment and some have brought new difficulties. Discussion of some of these, with cosmetic chemists and a clinical dermatologist meeting on common ground, may be mutually helpful. THE CHANGING SKIN Generally speaking, except for common skin diseases such as bacterial infections, infestations, contact dermatitis, etc., most topical treatment is used to remove or ameliorate a symptom. This symptom can be an expression of a systemic illness, but more often it is just a temporary functional variation from the physiological mean, as in epidermal keratinization and dermal functions involving sweat and sebaceous glands (including ache and seborrhoeic conditions), pigment formation, vascular activity including, for instance, frictional urticaria (dermographism), hypersensitive reactions to cold ("white fingers", chilblains), and other individual responses to radiant energy and the environment. These normal variations in personal physiological function or reaction to environment only require treatment when such factors produce temporary symptoms. A grosser disturbance of function from the mean may cause a sympto- matic but still only temporary state of inflammation from which recovery soon or gradually occurs. In those in whom the skin is genetically pre- disposed to be "an inferior organ" epidermal functions such as keratini- zation, or dermal functions such as sweating, or others may be so disturbed that the skin recovers only slowly, if ever, as in chronic eczema and estab- lished psoriasis. These patients may require continued symptomatic emollient and anti-inflammatory treatment. Greater emphasis should be placed on the prophylactic treatment of these constitutionally inferior skins before such chronic functional disturbance occurs. The problem is more complex because in all persons the physiological or enzymic function, biochemistry and often the anatomy varies considerably from area to area. As illustrations, skin grafted from the thigh to the forehead always remains as thigh-type skin in its new position the cycle of hair growth varies