sebum excretion by 22.5 %, which correlates with an improvement in acne lesions. It
is believed that the mechanism by which this occurs is due to a decrease in duct
obstruction.
When comparing keratolytic efficiency, 2 % benzoyl peroxide with retinoic acid
0.05 % and salicylic acid 2 %. Benzoyl peroxide was found to be significantly more
effective than retinoic acid or salicylic acid in case of clutch in the cornea after 3 hours.
However, after 6 years, all three agents gave a similar keratolysis. These results
demonstrate the keratolytic properties of benzoyl peroxide. The drug is able to discolor
hair, so it is recommended for use when combined with acne and hypertrichosis [19,
23].
Widely used for external acne treatment Azelaic acid - a bicarbonate carboxylic
acid, which is naturally formed on the normal skin during lipid metabolism and in small
quantities (4 - 90 ng/ml of blood) is contained in the human body. After applying to
the skin azelaic acid preparations easily penetrate into the epidermis and dermis.
Systemic blood flow reaches 4% of the total dose. Azelaic acid exhibits a moderate
anti-inflammatory, antioxidant, antimicrobial and anticaratinizing effect. Due to the
presence of two carbonic groups, azelaic acid can form complexes with bivalent cations
of calcium and magnesium, cofactors of enzymatic reactions, and also bind free
radicals. There is evidence that azelaic acid inhibits the synthesis of melanin by means
of a tyrosinase enzyme block, which may be undesirable in long-term use of azelaic
acid in patients with dark skin color due to the appearance of depigmentation. On the
other hand, for the light-skinned patients, the effect of inhibition of tyrosine azelaic
acid is used to treat post-inflammatory hyperpigmentation. Azelaic acid also has
antiandrogenic effect, suppressing the synthesis of 5α-reductase type I, which leads to
a decrease in the content of dehydrotestosterone, thereby normalizing the processes of
keratinization and salivation. It has been shown that azelaic acid eliminates
hyperkeratosis of the sebaceous glands follicles, reduces the thickness of the epidermis,
with prolonged use leads to the normalization of the process of differentiation of the
epidermis cells [3, 23].
There is evidence of bactericidal action against gram-positive and gram-negative
microorganisms, including antibiotic-resistant strains. In the literature of recent years,
there is information about the antifungal effect of azelaic acid. Thus, in vitro
experiments showed that 1% of azelaic acid has an effect against fungi of the genus
Pityrosporum ovale, Candida albicans, resistant to antibiotics, and to azelaic acid
itself, resistance to microorganisms is not formed even with prolonged exposure [14].
Azelaic acid is widely used in the treatment of acne. According to clinical trials,
it is effective both in monotherapy and in combination with antibiotics, retinoids and
benzoyl peroxide. Azelaic acid monotherapy can be recommended for supportive
therapy, for the treatment of comedone acne, papulopustulous acne with mild to
- 1519 -