Composition comprises a compound of the avermectin family comprising lipidic nanocapsules dispersed in a continuous hydrophilic phase, where the lipidic nanocapsules contain an internal oily phase in which the avermectin is solubilized and a solid lipophilic surfactant containing lecithins coats the internal oily phase at ambient temperature. An independent claim is included for a preparation of the composition comprising solubilization of the avermectin in liquid fatty substance at room temperature to obtain oily phase, mixing the hydrophilic compounds to obtain hydrophilic phase, dispersing lipophilic surfactant in the oily phase or in the hydrophilic phase, mixing the oily phase with the hydrophilic phase, and introducing the obtained mixture in a high pressure homogenizer to obtain a nanoemulsion. ACTIVITY : Dermatological; Antiseborrheic. MECHANISM OF ACTION : None given. No biological data given.