ABSTRACT
BACKGROUND: Clinical studies in cutaneous conditions other than actinic keratosis (AK) have revealed that the safety and efficacy profile of imiquimod is influenced by dosing frequency. OBJECTIVES: To evaluate dosing frequency response of imiquimod 5% for treatment of AK. METHODS: This was a phase II, multicentre, randomized, double-blind, placebo-controlled study. Adults with > or = 10 but < or = 50 clinical AKs, one of which was histologically confirmed, were randomized (4:1) to 2-6 packets of imiquimod or placebo cream applied to the dorsum of the forearms and hands once daily 2, 3, 5 or 7 times per week for 8 weeks. The primary endpoint was complete clearance of AKs in the treatment area at 8 weeks post-treatment. RESULTS: One hundred and forty-nine (94 men and 54 women) white subjects, with a mean +/- SD age of 71 +/- 10.2 years, were enrolled. Twenty-eight subjects (18.8%) discontinued from study: 0%, 3.1%, 6.9%, 30.0% and 33.3% withdrew for local skin reactions or adverse events in the combined placebo, and in the imiquimod 2, 3, 5 or 7 times per week groups, respectively. Seven serious adverse events occurred; none was related to the study drug. Median baseline lesions ranged from 38 to 40 for the treatment groups. Complete clearance was achieved in 0%, 3.2%, 6.9%, 3.3% and 6.7% of subjects, and partial clearance (> or = 75% lesion reduction) in 0%, 22.6%, 24.1%, 20.0% and 36.7% of subjects for the placebo and imiquimod 2, 3, 5 or 7 times per week regimens, respectively. CONCLUSIONS: Imiquimod 5% applied more frequently than 3 times per week to AKs was not well tolerated. Complete clearance rates were low; however, partial clearance rates increased with increased dosing frequency (P = 0.002).
