Vitamin A acid: a review of its pharmacological properties and therapeutic use in the topical treatment of acne vulgaris.

Vitamin A acid (retinoic acid: tretinoin) is a vitamin A derivative used in the topical treatment of acne. It acts by 'unseating' comedones, improvement developing slowly over a period of 2 to 3 or more months, and is also said to prevent the formation of new lesions. About three-quarters of patients with acne vulgaris benefit from treatment. In controlled studies, results achieved after a 3 to 4 months course of treatment were superior to those with sulphur-resorcinol-salicylic acid. When compared with benzoyl peroxide, results were variable and appear to depend on the length of treatment, the types of formulations used, and the concentrations compared. Application of vitamin A acid should be continued until the patient has been free of new lesions for several months. Further continued application at a less frequent interval or using a less active dosage form may help to prevent exacerbations of acne. A systemic antibacterial agent such as tetracycline can be given as well as in patients with moderate to severe lesions. Vitamin A acid is used in conjunction with gentle washing (to remove surface oil) but should be applied to a dry skin to avoid unnecessary irritation. Patient education and encouragement are crucial during the initial phase of treatment when microcomedones may be converted to pustules prior to desquamation.