Acne vulgaris topical agents

Tretinoin or retinoic acid is the acid form of vitamin A. Actually it is the all-trans isomer of retinoic acid. It is an effective topical agent for acne vulgaris. Its mechanism of action is believed to be associated with increased epidermal cell turnover. Some 10% of the topically applied dose is absorbed, metabolized by the liver and excreted in the urine and bile. To be effective tretinoin should be applied in a concentration that results in mild irritation and erythema. Patients should be advised to avoid or minimize sun exposure and use a protective sun screen as animal studies have raised some concern about possible carcinogenic effects under the influence of ultraviolet radiation. There are no indications that topical tretinoin is associated with an increased risk for birth defects. 

Benzoyl peroxide is an effective topical agent in the treatment of acne vulgaris. It penetrates the stratum corneum or follicular openings unchanged and is converted metabolically to benzoic acid within the epidermis and dermis. Less than 5% of an applied dose is absorbed from the skin in an 8-hour period. 

Azelaic acid is an antibiotic agent that inhibits microbial cellular protein synthesis. It is indicated in the topical treatment of mild to moderate inflammatory acne vulgaris (cream) topical treatment of papules and pustules of mild to moderate rosacea. 

Treatment has been difficult as the modalities that are useful in acne vulgaris are often ineffective in chloracne. Topical application of retinoic acid (0.005-0.3% concentration) or of tretinoin (Retin-A) gel or cream is of some benefit in controlling comedones, but other topical agents are of little use (Caputo et al. 1988). A combination of tetracycline and short courses of orally administered prednisone helped with severe inflammatory cases. A trial regimen of methotrexate, 25 mg every 10 days for several months was unsuccessful (Taylor et al. 1977). 

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