Azelaic acid is a dicarboxylic acid derived from Pityrosporum ovale; it was discovered a few years ago, possibly by chance, to be beneficial in acne. Italian and UK authors have  demonstrated in open  studies that  the drug  is effective in acne, even in very  severe acne. More recently this author's department showed it to be better than placebo.

The same  team has also demonstrated  that  the  drug is quite  effective, almost as much so as tetracycline. (It needs however to be emphasized that in this study it was not possible to include any placebo). A large multinational trial showed azelaic acid to be as effective as benzoyl peroxide, retinoic acid and tetracycline. Note  that in this  large study  there  were no controls.

 

  In   the   laboratory  azelaic   acid  reduces  5-areductase activity but there is no convincing evidence in vivo that the drug reduces the sebum excretion rate.

Studies of the effect of azelaic acid  on follicular casts have  not  been  performed  but  clinical measurement shows that  it  reduces the number of noninflamed lesions. A possible mechanism for this clinical observation is the change in keratohyalin granules, which are morphological markers of filaggrin,  the keratin aggregating protein.

Azelaic acid reduces free fatty acids by about 20 per cent but this effect could be less than real since azelaic acid  is itself a fatty acid and is sampled when  collecting the skin surface  lipids. Azelaic  acid reduces P. acnes by 1 log cycle; this is less than the effect seen with  benzoyl peroxide but of the same order as that  observed with oral  tetracycline 1 g/day. Azelaic acid reduces Staph,  epidermidis by 2-3 log cycles , an effect very similar to that seen with benzoyl peroxide and with oral antibiotics. However,  in  contrast  to  oral  antibiotics,  in  which Staph, epidermidis resistance occurs within 2-3 weeks, no  such resistance occurs in azelaic acid treated patients nor in patients receiving benzoyl peroxide.

  Azelaic acid is well tolerated and does not bleach the patient's clothes.