Azelaic acid: Pharmacology, toxicology and mechanism of action in acne

Azelaic acid: Properties and mode of action

Acne is a common skin disorder that can be problematic for adults as well as for adolescents. It has several key pathophysiological features such as follicular hyperkeratosis, elevated Propionibacterium acnes proliferation, and reactive inflammation, all of which should be targeted for an optimal outcome. Azelaic acid (AzA) has profound anti-inflammatory, antioxidative effects, and is bactericidal against a range of Gram-negative and Gram-positive microorganisms as well, including antibiotic-resistant bacterial strains. In addition, AzA's antikeratinizing effects are inhibitory toward comedones. AzA is effective overall in targeting multiple causes of acne and has been proven to be well tolerated in numerous clinical trials.

Finasteride inhibits 5 alpha-reductase activity in human dermal fibroblasts: prediction of its therapeutic application in androgen-related skin diseases

BACKGROUND

The potential role of finasteride in treating androgen related skin disorders was investigated.

METHODS

Pooled human dermal fibroblasts were used to assess the effect of finasteride on the 5 alpha-reductase activity in skin tissue. Vmax and Km were estimated in the presence of 0, 10, and 200 nM finasteride.

RESULTS

Vmax values remain constant near 1.20 pmol/mg protein/h in the presence of increasing concentrations of finasteride; however, apparent Km increases from 0.27 nM at 0 nM finasteride to 0.31 nM and 0.44 nM at 10 nM and 200 nM finasteride, respectively. This suggests that finasteride competes with testosterone and has a high affinity for same binding site of the 5 alpha-reductase enzyme. Apparent Ki was estimated at 282 nM, indicating that a high concentration of finasteride is required to significantly suppress the enzyme activity.

CONCLUSIONS

This study confirms that finasteride inhibits the conversion of testosterone to dihydrotestosterone in human reticular dermal fibroblasts. Finasteride may have therapeutic potential in treating skin disorders influenced by the action of dihydrotestosterone.

Percutaneous absorption of azelaic acid in humans

Six healthy male volunteers received a single topical treatment with 5 g of an anti-acne cream containing 20% azelaic acid (AzA) onto the face, the chest and the upper back. One week later 1 g of AzA was given orally to the same subjects as aqueous microcrystalline suspension. Following the two treatments the renal excretion of the unchanged compound was measured. Analysis included ether extraction of the urine, derivatization of extract and HPLC with UV detection. After topical application 2.2 +/- 0.7%, and after oral administration 61.2 +/- 8.8% of the dose had been excreted unchanged with the urine. By comparing both amounts, the percutaneous absorption of AzA from the cream was assessed to 3.6% of the dermally applied dose.