A particular type of skin lesion called actinic keratosis, caused by long-term exposure to the sun, responds well to thrice-weekly application of Aldara cream, which contains a 5 percent concentration of the drug imiquimod, US researchers report.

Actinic keratosis consist of abnormal skin cells, probably resulting from immune suppression caused by ultraviolet light, and they can sometimes become cancerous. Imiquimod stimulates the immune system, Dr. Neil Korman and colleagues note in the Archives of Dermatology, and so it could be “ideal” for treating actinic keratoses.

Korman, at University Hospitals of Cleveland in Ohio, and doctors at 26 study centers recruited 492 patients who had four to eight actinic keratoses in a 25 square centimeter area of the face or balding scalp.

The participants were randomly given cream containing 5 percent imiquimod or an inactive sham cream, and were instructed to apply it to the keratoses three times per week for 16 weeks - although they could take “rest periods” to minimize adverse effects.

The skin lesions cleared up completely in 48 percent of the imiquimod group but only 7 percent of the vehicle group. Corresponding rates of partial clearance were 64 percent and 14 percent.

The team notes that the clinical response to imiquimod applied three times per week was higher than that seen with twice-weekly appication in another study.

Localized itching occurred in 29 percent of those in the imiquimod group and 4 percent of those in the placebo group. Although local skin reactions were generally well tolerated, they led 10 subjects in the imiquimod group to discontinue treatment.

However, some discomfort seems to be the price of a good result. Korman’s group found that clearance rates were significantly associated with the intensity of local skin reactions, especially redness.

SOURCE: Archives of Dermatology, April 2005.