POTENTIAL OF ENZYMES FOR TOPICAL APPLICATION 259 portions of sebum which would otherwise be completely removed with fat solvents) that the development of such products would be well worth the added effort. IV. SUMMARY Whether or not an enzyme can be used for a given topical application depends on the nature of the cutaneous disorder as well as the limitations associated with the enzyme activity. To a large extent, the physiology and anatomy of the skin dictate the degree of success an enzyme prepara- tion might enjoy as a cosmetic or therapeutic agent. (The distinction between "cosmetic" and "therapeutic" has become extremely difficult to define and is in all probability more a question of semantics than of practical importance.) The enzyme group that has proved to be quite useful is the proteases, some of which have more suitable specificities than others. In addition, the search by suppliers for new enzymes active on the more refractory substrates continues. Recent studies of enzyme formulations suitable for topical use have shown that such dosage forms are relatively easy to handle. However, the choice of base, surface active agent, etc., is important to provide for a stable formulation. The choice of base is also important in determining the ease with which the enzyme present can be assayed. Since enzymes can act only in an aqueous environment, proper vehicle selection is also critical for the proper activity in silu. The mild conditions associated with the enzymatic process, dovetailed with the characteristics of healthy and pathological skin, provide for op- timism as far as the potential of enzymes for topical application is con- cerned. While all of the requirements of the cosmetic chemist cannot be met with currently available products, enzyme research and development is being conducted with these in mind. (Received February 8, 1963) REFERENCES (1) F. Haurowitz, Chemistry and Biology of Proteins, Academic Press, Inc., New York (1950). (2) W. H. Ward and H. P. Lundgren, Atdvances in Protein Chemistry, IX, Academic Press Inc., New York (1954). (3) Drug Topics, 106, July 16 (1962). (4) D. G. Welton, Skin Dermatol. in Practice, 4, 131 (1962). (5) R. G. Harry, Cosmetics: Their Principles and Practices, Chemical Publishing Co., New York (1956). (6) D. M. Pillsbury, et al., At Manual of Cutaneous Medicine, W. B. Saunders Co., Phil- adelphia (1961). (7) S. Rothman, Physiology and Biochemistry of the Skin, University of Chicago Press, Chicago (1954), p. 300. (8) H. W. Siemens, General Diagr. osis and Therapy of Skin Diseases, University of Chicago Press, Chicago (1958), p. 53. (9) D. R. Goddard and L. Michaelis, 5'. Biol. Chem., 106, 605 (1934). (10) D. R. Goddard and L. Michaelis, Ibid., 112, 361 (1935). (11) D. J. Millin and M. H. Smith, Nature, 189, 664 (1961).

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