ids, salts, amides or esters thereof, and more particularly hydroxy acids such as glycolic acid, lactic acid, malic acid, salicylic acid, citric acid and the fruit acids in general, and 5-n-octanoylsalicylic acid;antiseborrhoeics such as progesterone;antidandruff agents such as octopirox or zinc pyrithione;anti-acne agents such as retinoic acid or benzoyl peroxide.substances such as substance P an