Azelaic acid 20% is a naturally occurring saturated dicarboxylic a.

Structural Formula: HOOC-(CH₂)7-COOH (9 carbon atoms)

Azelaic acid is used as a treatment for acne vulgaris and is one of the leading treatments for this condition in Europe where it has been marketed as a 20 % cream since 1989.

Azelaic acid has also been successful in malignant melanoma and hyperpigmentary conditions such as lentigo maligna & melasma.

The drug was approved for the treatment of acne vulgaris September 13^th, 1995

• Antibacterial effectm on the follicular epidermis
• Antikeratinizing effect on the follicular epidermis
• Anti-inflammatory effect on the follicular epidermis

1. Azaderm possesses bactericidal properties against a variety of aerobic&anaerobic microorganisms , specially Staphilococcus epidermidis &Propionibacterium acnes which are known to be elevated in acne - bearing skin . (by inhibition of synthesis of microbial cellular proteins )
   -By reducing the concentration of bacteria present on the skin, Azelaic a. decrease the inflammation associated with acne lesions .( indirect )
   Azaderm also possesses a direct anti-inflammatory effect by scavenging oxygen radicals.
    
2. The antikeratinizing effect of azaderm may be due to decreased synthesis of filaggrin ( keratin filament aggregating protein ).
   By inhibiting filaggrin , azaderm normalize the kiratinization of the follicle and produce a reduction in non inflamed acne lesions.
   
   N.B Azelaic a. does not affect sebum excretion.

The antiproliferative and cytotoxic actions of azelaic acid may be due to reversible inhibition of a variety of oxidoreductive enzymes including DNA polymerase, tyrosinase, and mitochondrial enzymes of the respiratory chain.

Chloasma, also known as melasma, appears as a blotchy, brownish pigmentation on the face that develops slowly and fades with time.
Chloasma usually affects women but occasionally is seen in young men who use after-shave lotions, scented soaps, and other toiletries.

Chloasma is especially common in young women and affects the forehead, cheeks and upper lips. It occurs frequently during pregnancy and is more common in dark skins than in fair skins. Often called "the mask of pregnancy", (or the left side - if you drive on the right).

chloasma is more pronounced during the summer months as a result of sun exposure. It usually fades a few months after delivery. Repeated pregnancies, however, can intensify the pigmentation.

Chloasma also occurs as a side-effect of taking contraceptive pills and injected depot contraceptive preparations. It may also be noticed in apparently healthy, normal, non-pregnant women where it is presumed to be due to some mild and harmless hormonal imbalance.

Sun exposure, following the use of deodorant soaps, scented toiletries, and various cosmetics can also produce this mottled pigmentation.

This is called a phototoxic reaction and is due to ultraviolet radiation being absorbed by the chemical substance (perfume, cologne and other types of fragrance) on the skin. This pigmentation often extends down to the sun-exposed areas of the neck and may be more pronounced on the right side of the forehead, face and neck due to sun exposure while driving a car.

When Azaderm cream is applied topically in these conditions, there is a reduction in epidermal melanogenesis and a replacement of abnormal melanocytes by normal cells, flattening of nodular areas may also occur.

Hyperactive and malignant melanocytes are much more susceptible to the effects of azelaic a. than normal melanocytes

Negligible cutaneous metabolism occurs after topical administration . Azelaic a. is mainly excreted unchanged in the urine but does undergo some beta - oxidation to shorter chain dicarboxylic acids.

N.B. The drug penetrates into the stratum cornium following a single application to human skin in vitro ,(approximately 3-5 % of the applied dose ).
Approximately 4% of the topically applied dose is absorbed systemically .

Plasma concentrations and daily urinary excretion of azelaic a. are highly dependent on dietary intake. Following topical administration ,plasma concentrations and urinary excretion of azelaic a. are not significantly different from baseline levels.

The results of a recent study demonstrate that azelaic a. efficacy can be enhanced and patient ratings of overall impression improved , when it’s used in combination with other topical medication such as Benzoylperoxide- Tretinoin- &erythromycin/Benzoylperoxide.
Another study has shown that azelaic a. + benzoylperoxide
achieves greater efficacy & higher patient ratings of convenience than monotherapy with erythromycin/ benzoylperoxide.

Reference: J Am Acad Dermatol 2000; 43:S47-50