EFFICACY OF ANTIDANDRUFF FORMULATIONS 81 in the form of very fine scales. Visibility of scaling will mainly depend on the size of the flakes, while the corneocyte count chiefly reflects the rate of horny cell production. In any given scalp these may interact in different proportions. In consequence, the range of counts for any given grade may be quite large, especially in the nondandruff group. Some grade 2 individuals, for example, will have counts more typical of dandruff. Conversely, some grade 5 subjects will have counts in the nondandruff range. In these, cell turnover is not in- creased but aggregation is. On the other hand, counts and grades were strictly correlated when scaling was conspicuous. High grades in severe dandruff were almost always ac- companied by high counts. One can imagine a product that might be effective in dandruff without in any way altering the production of horny cells. Dandruff would "disap- pear" if the scales were simply dispersed into smaller aggregates. Tars might be examples of ancient antidandruff medications that depend on this mode of action. Restoration Time The quantity of scales on the scalp at any particular time will be depen- dent on the interval since the last thorough washing. By shampooing daily, dandruff cannot be visualized. It is important to know how long it takes after a vigorous shampoo for scaling to reach the prewashing level. Van Abbe and Dean estimate this to be about 5 days (4). This interval is, of course, not fixed and will become proportionately shorter as dandruff becomes severer. Without knowledge of the average restoration time one cannot sensibly lay out specifications for assaying antidandruff shampoos. If bland shampooing is done at intervals less than the restoration time, scaling must diminish pro- gressively. One could then falsely ascribe a beneficial effect to an inefllcaceous shampoo. If the intervals between shampoos are unusually long, say 10 days, this permits only 3 treatments a month. Each evaluation would then take months to complete. Effect of a Single Nonmedicated Shampooing Corneocyte counting and grading were done on 7 dandruff subjects. The scalps were then shampooed and counts made at the following times: im- mediately after shampooing, and 1, 2, and 4 days afterwards. Results-The initial grade before shampooing was 5.3. This fell to 2.0 one day later, increased to 2.8 on the second day, and reached 5.1 by the fourth. Immediately after the shampoo the mean count was 770,000/cm 2 com- pared to the 1,330,000/cm 2 originally. Twenty-four hours later, the count dropped still lower to 288,000/cm 2. It rose to 1,009,000/cm 2 by the fourth day.

82 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS In a further 8 subjects, 4 with heavy dandruff (average grade 5.7) and 4 with no dandruff (average grade 2.5), counts and gradings were done every 3 days for 12 days after a single shampoo. In the nondandruff group the counts returned to the preshampoo level of 763,000 cells/cm 2 by the sixth day and did not materialIy increase thereafter. The clinical grades probably decreased slightly at 24 hours. It is certain, however, that the scores did not continue to rise with time, they leveled off after the third day. The final grade at 12 days was no greater than .at 3. In the dandruff group, by contrast, the pretreatment average of 1,366,000 cells/cm 2 was surpassed by day 3 with a count of 1,450,000 cells. By day 6 the count had risen to 1,880,000 cells. The counts continued to increase there- after but only reached a final level 1,910,000/cm 2. A sharp levelling off clear- ly occurred after the 6th day. The grades increased to averages of 5.6 on day 3, to 7.4 by day 6, (the origi- naI level) 8.0 by 9, and 8.4 by 12 days. One subject reached grade 9 by 9 days. Effect o[ Shampooing Dandruff Subiects Every 4 Days It was necessary to know whether bland shampooing every 4 days would bring about a steady decline in counts. Accordingly, 15 subjects, each with grade 5 dandruff, were shampooed every 4 days. Counts and grades were determined initially (4 days after a preparative shampoo) and again at 8, 16, and 24 days, each time just before shampooing. Results-The mean initial count of 1,328,000 cells/cm • fell slightly to 1,- 270,000 at 8 days, did not change further by 16, and finally decreased a little more to 1,210,000 cells by 24 days. These reductions were not statistically significant even with a two-way analysis of variance. The grades likewise did not significantly decline throughout the 24-day period. Effect of Shampooing Dandruff Subjects Every 2 Days Six grade 5 dandruff subjects were shampooed every 2 days for 4 times. Results-The counts declined from 1,450,000/cm • to 860,000/cm • 2 days after the final shampoo. The signs of dandruff abated as the grades fell to 3.5 two days after the last shampoo. Comment-A single washing of dandruff subjects disclosed some interesting matters. Immediately afterward, the count was 60% of the preshampoo level, that is to say, two, vigorous 1-min shampooings removed only 40% of the cells. The two 1-min scrubs with a blunt rod for corneocyte counting is far more efficient. Curiously, the counts did not begin to rise immediately after shampooing. Indeed they were substantially lower 24 hours later. The effect .of washing is thus somewhat more complex than one might suppose. Perhaps thorough cleansing of the scalp removes oil and debris which tends to trap desquamat- ing material hence, loss of scales will be facilitated for perhaps a day or so