A double‐blind randomized vehicle‐controlled clinical trial investigating the effect of ZnPTO dose on the scalp vs. antidandruff efficacy and antimycotic activity

Synopsis Dandruff is a common problem in approximately 30% of the world's population. Reports in the literature regarding treatment of this condition with various antidandruff shampoos usually report the level of active ingredient within the formulation. However, we propose that a more important parameter relating to antidandruff efficacy is the amount of active ingredient delivered to the scalp from the shampoo. This report describes the results from two studies designed to investigate the relationship between the level of zinc pyrithione (ZnPTO) deposited onto the scalp and the resultant scalp condition. A double-blind randomized vehicle-controlled clinical study comparing three shampoos – a vehicle, a low-depositing ZnPTO shampoo and a high-depositing ZnPTO shampoo – was carried out in the U.K. with 53 panelists with dandruff or mild-to-moderate seborrheic dermatitis of the scalp. Both shampoos containing ZnPTO were significantly superior in antidandruff efficacy to the vehicle. Furthermore, the high-depositing ZnPTO shampoo was significantly superior compared with the low-depositing ZnPTO shampoo in terms of both antidandruff efficacy and antimycotic activity. Antidandruff performance and antimycotic activity of ZnPTO-containing shampoos is highly dependent on the amount of active ingredient delivered to the scalp. Furthermore, careful manipulation of the formulation parameters of an antidandruff shampoo can result in enhanced levels of delivery of the active ingredient without having to increase the level of active ingredient within the formulation. Resume Les pellicules sont un probleme courant rencontre par environ 30% de la population mondiale. Les rapports de la litterature relatifs a son traitement par des shampooings antipelliculaires mentionnent couramment le taux d'actif inclus dans la formule. Nous proposons cependant un parametre plus important, vis a vis de l'activite antipelliculaire, c'est a dire le taux d'actif delivre par le shampooing sur le cuir chevelu. Cet article decrit les resultats de deux etudes concues pour determiner les types de relation entre le taux de Zn PTO depose sur le cuir chevelu et l'etat de celui ci qui en resulte. Une etude randomisee, controlee par vehicule, a compare 3 shampooings (la base vehicule non traitante, un shampooing a faible deposition de Zn PTO et un shampooing a fort taux de depot de Zn PTO), a ete conduite au Royaume Uni sur 53 volontaires sujets pelliculaires ou a faible ou moderee Dermite Seborrheique. Les deux shampooings contenant le Zn PTO ont ete trouves significativement superieurs dans leur activite anti pelliculaire au vehicule. De plus, le shampooing a fort depot etait significativement plus efficace que celui a faible depot, tant dans l'activite anti pellicualire qu'anti mycotique. En conclusion, la performance anti pelliculaire et anti mycotique de shampooings a base de Zn PTO semble hautement dependante du taux d'actif delivre sur le cuir chevelu. De plus, un choix judicieux des parametres de formulation du shampooing anti pelliculaire peut amener a accroitre les taux de delivrance de l'actif sans avoir a augmenter celui ci au sein de la formule.