72 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table III The Effect of Scotch © tape Stripping on Sweat Gland Function Following Occlusive Treatment with 8% A1C13 • • q- S.E. Median Percentage of glands inhibited 92 -+ 3 97 Percentage of inhibited glands restored to firing 11 _+ 3 2 •N = 33 subjects AICI 3 Once again, 18 h of occlusive treatment nearly completely abolished sweating. However, in distinct contrast to the observations described above for ACH and AZAP, removal of the stratum corneum had little effect on restoring gland function. In fact, for 13 of the 33 subjects studied, no restoration of function whatsoever in the population of inhibited sweat glands was observed, that situation explaining the relatively large discrepancy between the average and median values for the percentage of restoration of inhibited glands (Table III). DISCUSSION Not unexpectedly, the overnight occlusive application of each of the three aluminum- based antiperspirant solutions resulted in virtually complete inhibition of sweat gland function. For ACH, however, despite the high level of effectiveness, the penetration of the polymer into the sweat gland duct is not extensive, as evidenced by the finding that half the inhibited glands are restored to normal function when the 25-35 /•m thick stratum corneum layer is removed. Similarly, AZAP's site of action is also quite superficial, with two-thirds of the inhibited glands being restored to firing following the stripping away of the horny layer. Statistical evaluation of the data demonstrated that the difference between the percentage of restored AZAP-inhibited glands (67%) and ACH-inhibited glands (51%) is significant (p .01). For both ACH and AZAP, the two most widely used commercial antiperspirant agents, the location of the inhibition of eccrine sweat gland function in the duct is relatively near the skin surface. On the other hand, in stark contrast to the observations made for ACH and AZAP, removal of the stratum corneum had little effect on attempts to restore the function of those sweat glands inhibited by A1C13, indicating that the primary site of action in the sweat duct for A1CI 3 is deeper than the level of the stratum corneum in nearly all instances. The difference in restoration between A1C13-inhibited glands (11%) and ACH- or AZAP-inhibited glands is significant (p .001). Similar findings for A1C13, although less precisely determined, have been reported by others (4,7). One possible reason for this difference in the primary sites of action between AIC13 and ACH or AZAP is that the aluminum species of A1CI 3, being smaller, are able to diffuse down the sweat duct more rapidly than the larger polycationic species of ACH and AZAP.

ANTIPERSPIRANT ACTION OF ALUMINUM SALTS 73 CONCLUSIONS The relative site of action within the sweat gland was determined for three antiperspirant agents, ACH, AZAP and AIC13 using the Scotch © tape stripping procedure. It was found that the primary site of action of ACH and AZAP was at the level of the stratum corneum layer, whereas A1CI3's site was deeper. REFERENCES (1) W. B. Shelley and P. N. Horvath, Comparative study on the effect of anticholinergic compounds on sweating,J. Invest. Derre. 16, 267-274 (1951). (2) H. M. Emrich and K.J. Ulrich, Auscheidung verscheidener Stoffe in Schweiss in Abhangigheit yon der Schweissfiussrate, Pflugers Archiv. 290, 298-314 (1%9). (3) K. Sato, J. R. Taylor and R. L. Dobson, The effect of ouabain on eccrine sweat gland function, J. Invest. Derre. 53,275-282 (1%9). (4) C. M. Papa and A. Kligman, Mechanism of eccrine anhidrosis. II. The antiperspirant effect of aluminum salts,J. Invest. Derre. 49, 139-145 (1%7). (5) H. H. Relier and W. L. Luedders, Pharmacologic and toxicologic effects of topically applied agents on the eccrine sweat glands. Part II. Mechanism of action of metal salt antiperspirant$, Adv. Mod. Tox. 4, 18-54 (1977). (6) J. M. Einbinder and R. A. Walzer, Separation of epidermis from dermis by use of disodium cantharadin,J. Invest. Derre. 41,109 (1%3). (7) B. I. Gordon and H. I. Maibach, Studies on the mechanism of aluminum anhidrosis, J. Invest. Derre. 50, 411-413 (1968). (8) J. Zahejsky and J. Rovensky, A comparison of the effectiveness of several external antiperspirants,J. $oc. Cosm. Chem. 23,775-789 (1972). (9) M. Wada and T. Takagaki, A simple and accurate method for detecting the secretion of sweat, Tokohu, J. Exp. Med. 49, 284 (1948). (10) Readi-Band ©, Parke Davis & Co., Detroit, MI. (11) Scotch Tape ©, 3M Company, St. Paul, MN.