SOME DIFFICULTIES OF TOPICAL TREATMENT IN DERMATOLOGY 33 generated by nylon or Terylene fabrics can also cause discomfort in these persons. These subjects also find the prickly effect of wool fibres uncom- fortable, or liable to cause eczema reactions. SWEAT DIFFICULTIES A considerable number of those with constitutionally dry skins will admit that they have never perspired easily or freely. Microtrauma on the skin will first show itself in a hyperkeratotic closure of the sweat duct (2) with obstructive dilatation of the duct, and interruption of sweat replacement of water to the keratin. Prickly heat eruptions (miliaria) in these dry-skinned persons are common in hot climates or environments, especially where clothes provoke a frictional microtrauma. Papular miliaria and eczema reactions thus occur in colliery workers where belt, lamp battery or cap hands minimally traumatize the skin, or in women wearing tight or rubberized foundation garments. The common and distressing symptom of anal irritation (pruritus ani) in non-sweating subjects also appears much influenced by sweat obstruc- tion. Persisting obstruction to sweat pores commonly leads to relapses in the form of papular eczemas of the body, or vesicular pompholyx eczema of the hands in those convalescent from contact dermatitis or eczema. Astringent face lotions, excessive sun burn, excessive use of Turkish baths may also provoke such symptoms, at a later date. ITCHING (PRURITUS) The itching sensation is produced by subliminal stimulation of pain fibres, and can be abolished by conversion to pain. The qualities of itching are sharp, needling pricks or more diffuse burning sensations. Agents cause itching either mechanically or by releasing polypeptides from de- graded protein produced by inflammation, enzymic effects of bacteria or other factors on the pain fibres. "School boy" itching powder from the plant Mucuna pruriens irritates mechanically, and by its polypeptide nature. Slight itching is physiologically normal in the skin due to such factors as friction of clothes, enzymic protein breakdown, bacterial growth, sweating, circulatory and temperature changes, although much personal and site differences exist in individuals. Dry skins are often more itchy pre- sumably through minor inflammations, sweat obstruction and abnormally keratinized scales catching on clothes.

34 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS EFFICACY OF TOPICAL TREATMENT Sedative and emollient medicaments Most generally used for slight keratin disorders is hydrous ointment, Ung. Aquosum, B.P.-w/o emulsion with wool alcohols ointment. It is effective as a hydrating agent but very greasy and less cosmetically pleasant than many proprietary w/o emulsions of liquid paraffin, soft paraffin, adeps lanae and emulsifying agents specially formulated for dry skins. Dry, chapped hands and brittle nails respond well, especially when the cream is used overnight under occlusive polythene gloves which increase hydration through reabsorbed perspiration. Chapped lips are less satisfactorily treated although emulsion creams with silicones help to lessen water evaporation. Self-emulsifying bath oils should find in- creasing use for senile skins and dyskeratotic skins in adverse climates. The oils seem well absorbed by abnormal keratinized skin, mineral oils adhere better than vegetable oils absorption being increased by temper- ature and duration of immersion ($). Some atopic eczema subjects are more comfortable if they bath twice a day in colder, dry weather. More severe degrees of ichthyosis are usually less satisfactorily treated by routine baths followed immediately by emollient greasy creams such as hydrous wool fat ointment, ung. adeps lanae hydrous containing hydrous wool fat and yellow soft paraffin, or wool alcohol ointments B.P. (wool alcohol 6% with hard, soft and liquid paraffins), or white petroleum jelly. Sodium chloride 10•o has been used in petroleum jelly to increase water holding capacity but some development of preparations along the lines of cosmetics with humectants which can be prescribed under a national formulary would be welcome. Cleansing agents and barrier creams Intolerance of soapy detergent cleansing agent is often on a personal basis due to alkali intolerance or penetration of fatty acids, more likely through non-intact keratin. Industrial barrier creams are now sub judice until controlled industrial trials under actual working conditions support or disprove the makers' claims. Most agree that the complete protective "invisible glove" is impossible to attain or maintain under normal working conditions, but that they are not entirely useless. They do not on their own prevent dermatitis, nor stop the entrance of sensitizing chemicals, and are only to be considered as a part of the general prevention programme. They