:296 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Strongly Basic, •,uaternary Type .,tnion Exchange Resin 1. Exchange of Anions Rz•-OH - 4- Na•-C1 - • Rz•C1 - 4- Na•-OH - 2. Neutralization Rz•-OH - 4- H •C1- • Rz •-C1- 4- H20 14Zeakly Basic, Polyamine Type .,tnion Exchange Resin 1. Exchange of Anions RzNHvH•O 4- Na•-C1 - .• RzNHvHC1 4- Na•-OH - 2. Neutralization RzNHvH•.O 4- H•-C1 - • RzNHvHC1 4- H•.O Figure 7.--Typical Equilibrium Reactions C. ztbsorption qf Skin [rritants--ztmberlite XE-87--zt Mixed Cation and zfnion Exchange Resin System A mixture of a sulfonic type cation exchange resin in the hydrogen form and of a quaternary ammonium resin in the hydroxyl form is useful com- mercially for the deionization of water and the processing of chemicals. Simultaneous exchange of cations for hydrogen ions and of anions for hydroxyl ions takes place, and the resulting hydrogen and hydroxyl ions neutralize one another. The application of such a mixture in powdered oeorm to body surfaces encounters some disadvantages and difficulties. The pH of the skin is not properly controlled as these two resins do not act as a buffering system however, when a cation exchange resin having carboxylic groups and an anion exchange resin possessing amino groups are added to the mixture, an effective buffer system is formed. The strong acid and strong base resin components absorb irritating electrolytes on the skin, while the weakly ionized carboxylic and polyamine resins buffer the first pair of resins. In a mixture of the four types of ion exchange resins, the amount of a sulfonic type cation exchange resin used is stoichiometrically equivalent to the amount of the strongly basic, quaternary ammonium resin. Similarly, the pair of weakly ionized carboxylic cation exchange resins and polyamine4 type anion exchange resins is stoichiometrically balanced. The ratio of the first pair of exchange resins (sulfonic and quaternary ammonium) to the second pair (carboxylic and polyamine) ranges from two-to-one to about one-to-five by weight. Any such mixture yields a careful com- promise between two conflicting properties. A larger proportion of the first pair would give higher capacity for absorbing undesirable substances, while higher proportions of the second pair would increase the buffering capacity of the total system. One of these mixtures used dermatologically is identified by the commercial designation Amberlite XE-87. As an example of the applications of these principles of action, Thurmon has shown the effectiveness of cation-anion exchange resin systems in hand creams as a means of correcting the development of alkalinity on the

RESINS AND THEIR APPLICATION TO DRUG AND COSMETIC PRODUCTS 297 skin from contact with common soap. This information is summarized in Table 2. Thurmon has also applied the principles of skin deionization by ion exchange to the treatment of dermatitis resulting from skin contact with poison ivy, oak and sumac (17, 18). His studies included in vitro patch tests using simulated irritant solutions containing urushiol, which is closely related in structure to the main skin irritant of the poison ivy plant. In vivo studies with an Amberlite XE-87 system in a variety of bases re- vealed that the ion exchange resin system gave greater relief for longer periods of time and cleared the positive reaction sites days sooner than other medications studied. D. Deodorant-dntiperspirant Compositions--.dmberlite XE-6•t--.d Car- boxylic Resin The combination of aluminum salts and Amberlite XE-64, a carboxylic type cation exchange resin in the hydrogen cycle, as an admixture was TABLE 2--T•r. ACTION OF AMBEKLITE XE-64 AND AMBEKLITE XE-87 IN VAKIOUS OINTMENT BASES t APPLIED TO ADULT MALE PALM* Concentra- Time tion of Applied pH pH Amberlife in Before After Difference, Amberlite Base Resin, % Minutes Application Application pH XE-64 Hydrophilic 25 10 10.0 6.3 3.7 U.S.P. XIV XE-64 Beelet Base 25 10 8.5 4.9 3.6 XE-87 Hydrophilic 25 10 8.3 5.8 2.5 U.S.P. XIV XE-64 Beelet Base 25 5 8.8 5.3 3.5 XE-64 Hydrophiiic 25 1 8.4 5.2 3.2 U.S.P. XIV XE-64 Glycerol 25 1 8.6 4.8 3.8 Methocel XE-64 Polyethylene 25 1 8.7 5.0 3.7 * Normal measured pH of this palm 4.7. • Tests with Yardley Shaving Bowl Soap. shown by Thurmon (19) to be unique in respect to its absence of irritant effects in individuals who are sensitive to common aluminum antiperspirant products. This combination effectively removes such materials as amino acids, which, through decomposition or putrefactive action by bacteria, can lead to irritating or malodorous products. Levels of Amberlite XE-64 as low as 2 per cent and as high as 35 per cent combined with from 5 to 25 per cent of a water soluble aluminum salt have proved to be effective. PREVENTIVE MAINTENANCE APPROACH TO SKIN HEALTH The ability of ion exchange resins to react upon demand by means of an ion exchange interreaction with invading skin irritants provides a means of developing an effective skin protective system.