36 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ticant reduction in sweating and in the case of one of them the reduction was comparable to that obtained with aluminium chlorhydrate. Prelimin- ary tests indicated a reduction in emotionally-induced finger sweating. Some of the more interesting materials for consideration as possible antiperspirant ingredients are anticholinergic drugs, which are para- sympathetic blocking agents (64). Impulses carried by the parasympathetic system stimulate eccrine sweat secretion under parasympathetic stimu- lation, acetylcholine is formed at the peripheral nerve endings and serves as the chemical mediator transferring impulses to the receptor cell in the secretory region of the gland. Acetylcholine is rapidly broken down when excitation of the nerve ceases. An anticholinergic agent does not block formation of acetylcholine but in some way prevents the receptor cell responding to it, so theoretically anticholinergic agents can be utilized to suppress sweating. Unfortunately both natural and many synthetic anti- cholinergics are not very selective in their action and unpleasant side-effects (dryness of the eyes and mouth, headache, blurring of vision, dizziness, hesitancy of micturition) may occur. Although many of the side-effects are reduced if the administration is topical rather than by injection, because the ability of these compounds to penetrate skin is poor, for the same reason their effects on sweating may be less than that obtained with aluminium chlorhydrate. Iontophoresis of the drugs would promote absorption, but is of limited practical value as it requires medical super- vision. MacMillan et at (26) found that esters containing one or more elements of the attopine or scopolamine structure were most effective in reducing perspiration and effectiveness was related to skin penetration in the case of the esters of scopolamine hydrobromide. A 0.025% solution of the benzoyl ester of scopolamine could be applied repeatedly to a limited area of the body without any evident systemic effects the authors estimated that the whole body surface would have to be covered more than once to promote even minimal systemic effects. This solution gave a 35% reduction in axillary sweating. Reductions in sweating of 40-68}/0 were obtained by repeated daily applications of 0.5}/0 solutions of hexopyrronium bromide (25), and it was calculated that subjects used about 15 ml of this solution per week. Used on the abdomen, under occlusion, a 1.0}/o solution of hexopyrronium bromide gave complete inactivation of sweating for a period of 2-3 days, but three out of fifty subjects experienced side-effects (53). A 4ø//0 solution of poldine methosulphate (Nacton) caused complete

MEASUREMENT AND CONTROL OF PERSPIRATION 37 suppression for 2-3 days on the forearm, but was less effective in water than in alcohol (54). Possibly because of lack of penetration, poldine metho- sulphate was less effective on the palms, soles and axilhe than on other areas of the limbs and trunk. Studies on the foot-pad of mouse and rat (21) using two anticholinergics Priamide (1.0% and 2.5% in alcohol), and BRL 556 (1.0%, 3.0% and 10% in alcohol) showed an inhibiting effect, the duration of which depended on the concentration and amount applied. Although applications were made on one foot only, the inhibiting effect was frequently seen in the other foot pad also. The importance of the vehicle on the efficacy of an antiperspirant has been shown by Kligman (65, 66) who used dimethyl sulfoxide (DMSO) to aid penetration of aluminium salts. Although this particular vehicle is not suitable for incqusion in cosmetic products because of its toxicity, other less toxic vehicles which show a potentiating effect may be available and should be considered when the antiperspirant product is formulated. MECHANISM OF THE EFFECT OF ANTIPERSPIRANTS The mechanism by which antiperspirants exert their effect is not com- pletely clear. With regard to aluminium salts one suggestion (11) was that they cause narrowing of the sweat duct by protein precipitation and enhanced keratin- ization. Another suggestion (4) was that the secretory portion of the duct carried a negative charge which attracted the biologically electro-positively charged aluminium salts, thus inhibiting sweating. Penetration studies of aluminium salts (67) using radio-tracer tech- niques, suggested that following topical application insufficient aluminium reached the dermis to exert a physiological effect on the gland. Papa (68), and Papa and Kligman (69) described experiments in which Sellotape stripping, methylene blue iontophoresis and histological examin- ation were carried out to determine the action of the anhidrosis brought about by water, formalin, and aluminium salts. From their results they suggested that the temporary anhidrosis caused by water is due to swelling of the horny cells near the eccrine duct orifice which causes closure of the pore. With formalin a plug of material is formed in the duct due to protein precipitation. In the case of aluminium salts the authors postulated that there is an alteration in the permeability of the epidermal portion of the duct and although the gland functions normally, the sweat leaks out into