Original article
Imiquimod 2.5% and 3.75% for the treatment of actinic keratoses: Results of two placebo-controlled studies of daily application to the face and balding scalp for two 3-week cycles

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Background

Imiquimod 5% cream is approved as a 16-week regimen for the treatment of actinic keratoses involving a 25-cm2 area of skin.

Objective

We sought to evaluate imiquimod 2.5% and 3.75% creams for short-course treatment of the entire face and scalp.

Methods

In two identical studies, adults with 5 to 20 lesions were randomized to placebo, or imiquimod 2.5% or 3.75% cream (1:1:1). Up to two packets (250 mg each) were applied per dose once daily for two 3-week treatment cycles, with a 3-week, no-treatment interval. Efficacy was assessed at 8 weeks posttreatment.

Results

In all, 490 subjects were randomized to placebo, or imiquimod 2.5% or 3.75% cream. Median baseline lesion counts for the treatment groups were 9 to 10. Complete and partial clearance rates were 5.5% and 12.8% for placebo, 25.0% and 42.7% for imiquimod 2.5%, and 34.0% and 53.7% for imiquimod 3.75% (P < .001, each imiquimod vs placebo; P = .034, 3.75% vs 2.5% for partial clearance). Median reductions from baseline in lesion count were 23.6%, 66.7%, and 80.0% for the placebo, imiquimod 2.5%, and imiquimod 3.75% groups, respectively (P < .001 each imiquimod vs placebo). There were few treatment-related discontinuations. Temporary treatment interruption (rest) rates were 0%, 17.1%, and 27.2% for the placebo, imiquimod 2.5%, and imiquimod 3.75%, respectively.

Limitations

Local effects of imiquimod, including erythema, may have led to investigator and subject bias.

Conclusions

Both imiquimod 2.5% and 3.75% creams were more effective than placebo and had an acceptable safety profile when administered daily as a 3-week on/off/on regimen.

Section snippets

Study population

Adults in general good health with 5 to 20 visible or palpable AKs in an area greater than 25 cm2 in size on either the face or the balding scalp, but not both, were eligible for participation in the studies. A study subject could not have any significant condition in the treatment area that might impair evaluation, have atypical AKs (eg, AK >1 cm2 in size), be pregnant or lactating, have a chemical or alcohol dependency, or have a known allergy to imiquimod or study cream excipients. Prior

Subject population

In the combined studies, 490 male and female patients (Fig 2) were enrolled and 463 completed the studies. The most frequent reason for discontinuation was for personal reasons (11 subjects), followed by AEs (7 subjects). The majority of subjects were male (79%), white (99%), and treated the face (72%); their mean age was 65 years (Table I). The treatment groups were considered comparable with respect to demographic characteristics within and across the two studies. Overall, 96% of subjects

Discussion

In two multicenter studies conducted in parallel, both imiquimod 2.5% cream and imiquimod 3.75% cream were safe and effective in treating AKs on the full face or balding scalp when applied as a 3-week on/off/on treatment regimen. Each of the imiquimod creams was superior to placebo cream with respect to complete clearance rates, partial clearance rates, and median percent lesion reductions. These efficacy outcomes were greater in the imiquimod 3.75% group compared with the 2.5% group, although

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  • Cited by (0)

    Supported by Graceway Pharmaceuticals LLC.

    Disclosure: Drs Hanke and Beer were investigators and consultants for Graceway and received compensation for services. Drs Stockfleth and Rosen were consultants for Graceway and received compensation for services. Drs Wu and Levy are employees of Graceway.

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