PHYSICAL CHEMICAL ANALYSIS OF PERCUTANEOUS ABSORPTION PROCESS 85 (11). Cosmetics applied to skin previously exposed t'o solvents may be expected to penetrate more readily and possibly cause irritation. Depil- atory creams and cold-wave solutions may be alkaline only if their pH is g•eater than 11.5 will the barrier be sufficiently damaged to alter permea- bility. REFERENCES (1) Griesemer, R. D., "Protection Against the Transfer of Matter Through the Skin," In The Human Integument, Am. Assoc. Advance. Sci. Pub. No. 54 (1959), pp. 2546. (2) Mali, J. W. H., 2 •. Invest. Dermatol., 27, 451 (1956). (3) Blank, I. H., Ibid., 18, 433 (1952). (4) Higuchi, T., 2 •. Soc Cosmetic Chemists, 11, 85 (1960). (5) Blank, I. H., and Gould, E., "Penetration of Anionic Surfactants into Skin. I. Pene- tration of Sodium Laurate and Sodium Dodec51 Sulfate into Excised Human Skin," 2 •. Invest. Dermatol., 33, 327 (1959). (6) Szakall, A., Fette, Seifen, dnstrichmittel, 53, 399 (1951). (7) Stoughton, R. B., "Relation of the Anatom) of Normal and Abnormal Skin to its Pro- tective Function," In The Human Integument, Am. Assoc. Advance. Sci. Pub. No. 54 (1959), pp. 3-24. (8) Selby, C. C., 2 •. Invest. Dermatol., 29, 131 (1957). (9) Treherne, J. E., 2 •. Physiol. (London), 133, 171 (1956). (10) Blank, I. H., Personal communication. (11) Blank, I. H., Personal communication. PHYSICAL CHEMICAL ANALYSIS OF PERCUTA- NEOUS ABSORPTION PROCESS FROM CREAMS AND OINTMENT S BY T. HIotycm* Presented September 23-24, 1959, Seminar, New York City PROBI•EMS ^SSOCI.•TEt) with penetration of intact skin are, of course, of great interest to both pharmaceutical and cosmetic chemists. Not only are we concerned with maximizing the rate of penetration of beneficial drugs from ointments and lotions but also in minimizing the rate of entry of toxic chemicals, as such, or from drug and cosmetic preparations. In this brief discussion I hope to review from the viewpoint of a physicat chemist some'of the factors which may govern the rate of the penetratio- process. Despite the large amount of work already carried out in this field, there is very little agreement on the basis process which is largely responsible for percutaneous absorption through the intact skin. Many workers feel that essentially all penetration occurs through the transfollicular route. Other equally recognized investigators support the view that the major pathway of entry is transepidermal through the intact cornified and transition * School of Pharmacy, University of Wisconsin, Madison, Wis.

PHYSICAL CHEMICAL ANALYSIS OF PERCUTANEOUS ABSORPTION PROCESS 85 (11). Cosmetics applied to skin previously exposed t'o solvents may be expected to penetrate more readily and possibly cause irritation. Depil- atory creams and cold-wave solutions may be alkaline only if their pH is g•eater than 11.5 will the barrier be sufficiently damaged to alter permea- bility. REFERENCES (1) Griesemer, R. D., "Protection Against the Transfer of Matter Through the Skin," In The Human Integument, Am. Assoc. Advance. Sci. Pub. No. 54 (1959), pp. 2546. (2) Mali, J. W. H., 2 •. Invest. Dermatol., 27, 451 (1956). (3) Blank, I. H., Ibid., 18, 433 (1952). (4) Higuchi, T., 2 •. Soc Cosmetic Chemists, 11, 85 (1960). (5) Blank, I. H., and Gould, E., "Penetration of Anionic Surfactants into Skin. I. Pene- tration of Sodium Laurate and Sodium Dodec51 Sulfate into Excised Human Skin," 2 •. Invest. Dermatol., 33, 327 (1959). (6) Szakall, A., Fette, Seifen, dnstrichmittel, 53, 399 (1951). (7) Stoughton, R. B., "Relation of the Anatom) of Normal and Abnormal Skin to its Pro- tective Function," In The Human Integument, Am. Assoc. Advance. Sci. Pub. No. 54 (1959), pp. 3-24. (8) Selby, C. C., 2 •. Invest. Dermatol., 29, 131 (1957). (9) Treherne, J. E., 2 •. Physiol. (London), 133, 171 (1956). (10) Blank, I. H., Personal communication. (11) Blank, I. H., Personal communication. PHYSICAL CHEMICAL ANALYSIS OF PERCUTA- NEOUS ABSORPTION PROCESS FROM CREAMS AND OINTMENT S BY T. HIotycm* Presented September 23-24, 1959, Seminar, New York City PROBI•EMS ^SSOCI.•TEt) with penetration of intact skin are, of course, of great interest to both pharmaceutical and cosmetic chemists. Not only are we concerned with maximizing the rate of penetration of beneficial drugs from ointments and lotions but also in minimizing the rate of entry of toxic chemicals, as such, or from drug and cosmetic preparations. In this brief discussion I hope to review from the viewpoint of a physicat chemist some'of the factors which may govern the rate of the penetratio- process. Despite the large amount of work already carried out in this field, there is very little agreement on the basis process which is largely responsible for percutaneous absorption through the intact skin. Many workers feel that essentially all penetration occurs through the transfollicular route. Other equally recognized investigators support the view that the major pathway of entry is transepidermal through the intact cornified and transition * School of Pharmacy, University of Wisconsin, Madison, Wis.