306 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS SUMMARY We have attempted to examine an animal model which would be more relevant to man than the animals used in the past to determine percutaneous absorption of compounds. We have an animal model, the rhesus monkey, in which some absorption data was comparable to man. We realize that the data are limited to the few comparative studies reviewed, and therefore the animal model must still be assumed limited and experimental in nature. The results are encouraging enough to warrant continued use of this animal model when the opportunity is available. We have attempted to design percutaneous absorption studies which we believe to be more relevant to the clinical situation than the classical procedures used previously. Our results at times have been as expected, and at other times the results have been quite different than what was expected. However, these are first attempts in new areas of endeavor and they should hopefully provoke new interest in explaining percuta- neous absorption. Future studies in both animals and man with new approaches in experimental design will lead to results which will impact greatly in the toxicology and clinical efficacy of topical compounds. REFERENCES (1) R. C. Wester and H. I. Maibach, Percutaneous absorption in the rhesus monkey compared to man, ToxicoL Appli. PharmacoL, 32, 394-8 (1975). (2) M.J. Bartek, J. A. LaBudde and H. I. Maibach, Skin permeability in vivo.' comparison in rat, rabbit, pig and man,J. Invest. DermatoL, 58, 114-23 (1972). (3) R.J. Feldmann and H. I. Maibach, Percutaneous penetration of steroids in man,J. Invest. Dermatol., 52, 89-94 (1969). (4) R.J. Feldmann and H. I. Maibach, Absorption of some organic compounds through the skin in man, J. Invest. Dermato/., 54, 399-404 (1969). (5) R. C. Wester and H. I. Maibach, Relationship of topical dose and percutaneous absorption in rhesus monkey and man,J. Invest. DermatoL, 67, 518-20 (1976). (6) R.J. Feldmann and H. I. Maibach, Regional variation in percutaneous penetration of •4C cortisone in man, J. Invest. DermatoL, 48, 181-3 (1967). (7) H. I. Maibach, R.J. Feldmann, T. H. Milby and W. F. Serat, Regional variation in percutaneous penetration in man, Pesticides Arch. Environ. Health, 23, 208-11 (1971). (8) R. C. Wester, Unreported observations. (9) R. C. Wester and H. I. Maibach, Rhesus monkey as an animal model for percutaneous absorption, in H. Maibach, "Animal Models in Dermatology," Churchill Livingstone: New York, N.Y., 1975 pp 133-137. (10) R. C. Wester and H. I. Maibach, Percutaneous absorption in man and animal: a perspective, in V. Drill and P. Lazar, "Cutaneous Toxicity," Academic Press, Inc.: New York, N.Y., 1977 pp 111-126. (11) M.J. Bartek andJ. A. LaBudde, Percutaneous absorption, in vitro, in H. Maibach, "Animal Models in Dermatology," Churchill Livingstone: New York, N.Y., 1974 pp 103-120. (12) A.J.W. Sinha, S. R. Shaw and D.J. Weber, Percutaneous absorption and excretion of tritium-labeled diflorasone diacetate, a new topical corticosteroid in the rat, monkey and man, J. Invest, Dermatol., 71, 372-7 (1978).- (13) F. N. Marzulli, D. W. C. Brown and H. I. Maibach, Techniques for studying skin penetration, ToxicoL AppL Pharmacol. Suppl. 3, 76-83 (1969). (14) R. J. Scheuplein and L. W. Ross, Mechanism of percutaneous absorption. V. Percutaneous absorption of solvent deposited solids,J. Invest. Dermatol. 62,353-60 (1974). (15) R. C. Wester, P. K. Noonan and H. I. Maibach, Frequency of application on percutaneous absorption of hydrocortisone, Arch. Dermatol. 113, 620-2 (1977).

PERCUTANEOUS ABSORPTION IN RHESUS MONKEY 307 (16) R. C. Wester, P. K. Noonan and H. I. Maibach, Percutaneous absorption of hydrocortisone increases significantly with chronic application, Clin. Res., 27, 138A (1979). (17) M. K. Polano and M. Ponec, Dependence of corticosteroid penetration on the vehicle, Arch. Dermatol. 112,675-80 (1976). (18) R. C. Wester, P. K. Noonan and H. I. Maibach, Effect of salicylic acid on the percutaneous absorption of hydrocortisone. In vivo studies in the rhesus monkey, Arch. Dermatol. 114, 1162-4 (1978). - (19) M. S. Roberts and E. Horlock, Effect of repeated skin application on percutaneous absorption of salicylic acid,J. Pharm. $ci., 67, 1685-7 (1978). (20) R. C. Wester, P. K. Noonan, M.P. Cole and H. I. Maibach, Percutaneous absorption of testosterone in the newborn rhesus monkey: comparison to the adult. Pediat. Res., 11,737-9 (1977).