THE CLINICAL EVALUATION OF ANTIDANDRUFF SHAMPOOS 449 The progress made by individual subjects in a dandruff trial is well illustrated by means of a ternary diagram (Fig. $) showing the cumulative effect of continued usage this indicates in concise form not only the bene- ficial effect of a product but also the proportion of subjects whose dandruff level remains unchanged or increases. In this trial the product was consid- ered to have a beneficial effect when the dandruff level after treatment was half, or less, of that before treatment. IDO•. OF • SUBJECTS UNCHANGED COOKE lOO• OF O PLACEBO SHAMPOO, after I months' use SUBJECTS IMPROVED ß • • ACTIVE SHAMPOO, after I manlbs' use 0•, OF SUBJECTS IMPROVED SU•ECTS WORSE Figure $ Proportion of subjects showing improvement, no change, or worsening of their dandruff' (Rapid method of inspection). The results shown here cannot justifiably be taken to indicate the numbers of subjects necessary in antidandruff trials generally, since this will also depend on the efficacy of the treatment under test these numbers were nevertheless clearly adequate in the examples quoted. DISCUSSION Experience has taught us that treatments to combat dandruff require to be evaluated no less stringently than medicaments for correcting other chronic disorders. Good organization and, in particular, utilizing the "double-blind" method of clinical trial are exceedingly valuable. Unfortun- ately, it does not seem to have been appreciated in the past that the clinical impressions of a busy consultant, undertaking a trial as an isolated experiment and with no proper controls, will scarcely do more than

450 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS confirm the obvious and confuse the more subtle differences between various treatments. Nevertheless the supervision of a dermatologist is essential to provide guidance on correct diagnosis and to safeguard the interests of the volunteer participants. For the purpose of taking measurements, however, it is desirable to employ specially-trained observers, the reliability of whose results has been rigorously tested such observers need not be medically qualified. Despite the supposedly ubiquitous occurrence of dandruff, we have never found it easy to recruit large numbers of severe sufferers for trials this may have been a blessing in disguise, insofar as it has inspired us to devise techniques applicable to the available numbers of volunteers. The clinical studies reported here should not, however, be considered to be adequate to establish fully the efficacy of the proposed formulation. It is, for example, necessary to determine whether efficacy is maintained over many months of usage or whether resistance develops in this particular case, another experiment continuing for 12 months has, in fact, shown that reductions in dandruff levels were satisfactorily maintained but the short term studies are naturally undertaken first, primarily for screening pur- poses. It is interesting to note the finding that about 10 weeks are required to re-establish starting levels of dandruff when treatment has reduced it virtually to zero. The true induction period for dandruff is probably rather less than this, however, since the treatment is likely to have exerted some "carry over" effect. Whenever clinical trials are conducted, according to the patterns discussed here or in other ways, it is important to keep detailed records of any adverse effects (in addition to worsening of the condition under examination). These will generally be confined to mild episodes of transient erythema or itching but the supervising dermatologist will certainly wish to examine anything more than this in some detail. Comparison between test and control products on the incidence of physiological reactions should be made, to show whether irritancy is due to the active constituents or the shampoo base itself or even to establish whether the active constituents may have an anti-irritant effect. ACKNOWLEDGEMENTS The authors wish to thank Dr. W. G. Tillman, who supervised the work reported here as consulting dermatologist. (Received: 2$th August 1966)