EFFICACY OF ANTIDANDRUFF FORMULATIONS 85 Table II Comparison of 2.0% Zinc Pyrithione Shampoo with the Detergent Base Alone Corneocyte Count Clinical Grades Material Day 0 Day 14 Day 28 Day 0 Day 14 Day 28 Detergent base 1 256 000 1 148 000 1 174 000 5.4 4.9 4.7 Zinc pyrithione 968 000 678 000 732 000 5.6 3.1 1.9 Table III Comparative Efficacy of ZPT and Selenium Sulfide by Comeocyte Counting (Geometric Means) Shmnpoo Subjects Before Treatment Post-Treatment (/cm 2) (/cm2) Selenium sulfide 16 1 056 000 214 200 Zinc pyrithione 24 904 000 622 700 ZPT detergent base 18 I 169 000 1 041 000 Druco 1'8 I 150 000 1 040 000 Example/-Complete analysis: A shampoo containing 2% zinc pyrithione* was compared to the .detergent base in two groups of 10 men each. The re- sults are shown in Table II. With the base, the corneocyte count decreased slightly and the clinical grade by only 0.7. This difference was not significant (p= 0.05). Highly significant decreases occurred with the active ma- terial. The mean grade decreased from 5.6 to 1.9 and the count fell by almost a quarter of a million cells, highly significant differences. Effectiveness was already apparent by 14 days. Example H-Abbreviated test with corneocyte counts: The refinements provided by corneocyte counting are illustrated by the following short-term study. Dandruff subjects were shampooed twice weekly for only four times with a final count 4 days after the last shampoo. Two nonmedicated shampoos were compared to 2.5% selenium sulfide shampoo (Selsun Suspension©*) and 2% zinc pyrithione (Head and Shoulders). The results are shown in Table III. The counts were not lowered by the two bland shampoos. Significant decreases occurred with both active ma- terials (p = 0.01). The effect of the selenium shampoo was greater than zinc pyrithione this difference was significant (p = 0.05). It has repeatedly been our experience that zinc pyrithione acts less rapidly than selenium sul- fide. It should be noted that such rapid abatement of dandruff can only be ap- preciated with highly effective shampoos. Agents of lesser efficacy must be evaluated over a longer period of use. *Hea.d and Shoulders, Procter & Gamble Co., Cincinnati, Ohio 45224. tAbbott Co., Chicago, Ill.

86 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Assay o[ Antidandruff Grooming Agents Procedure The test material is applied once daily for 3 weeks the scalp is shampooed once weekly with a bland shampoo. The control reading is made 7 days after a preparative shampoo and the final one the 28th day (7 days after the last application and shampoo). The longer interval between shampoos increases the reliability of clinical grading by allowing more time for scales to accumu- late. Example Two per cent zinc pyrithione in Hydrophilic Ointment U.S.P. was compared with Hydrophilic Ointment U.S.P. alone in two groups of 10 men each. The agents were applied once daily for 4 weeks with bland shampooing once weekly. We now recommend 3 weeks of treatment. As a further point of interest, within each group, 5 had dandruff (grade 5) and 5 did not (grade 3). Grades and corneocyte counts were done once weekly. Results The corneocyte counts again provided the most eloquent evidence of the difference between treatments. In the dandruff subjects ZPT caused a great reduction from 1.75 x 106 to 4 x 105/cm 2 by 2 weeks (Fig. 5). Grades paral- leled the counts falling from 5.8 to 3.8 by 2 weeks and to 2.7 by 4. These were statistically significant changes (p = 0.01). With hydrophilic ointment, the grades only decreased from 5.2 to 4.6. The counts decreased but not signif- icantly so. In the nondandruff group the counts decreased modestly with both formulations. These differences were not significant. Comment Only tentative conclusions can be derived from such small samples. It seems unmistakable that effective grooming agents can be recognized with great confidence within 2 weeks provided that the subjects actually have dandruff. Further study is required to establish whether the mild suppressive effect of hydrophilic ointment in subjects with and without dandruff is a real phenom- enon. The results suggest that unmedicated cream bases may promote des- quamarion of finer scales from the surface. It need hardly be questioned that antidandruff effects are obtained more promptly with daily topical applica- tion than by twice weekly shampooing with the same active agent. Discussion It may be well to state the conceptions which form the foundation for the methods we have described. Dandruff occurs only on the scalp and has a sin-