ActinicKeratosesNet Article
Patients' Responses to Imiquimod Vary
Studies find different doses can be safe and effective

In 2004, the U.S. Food and Drug Administration (FDA) approved imiquimod for the treatment of actinic keratoses (ak-'tin-nik ker-e-'to-ses), also called AKs, on the face and scalp. The recommended dosage for this cream is 2 times per week for up to 16 weeks.

Clinical trials conducted to obtain FDA approval determined the recommended dosage. During the trials, 436 patients who had four (4) to eight (8) AKs on their face or scalp were randomly assigned to receive either 5% imiquimod cream or a cream that resembled imiquimod but lacked the active ingredient. Patients were instructed to apply the cream they received 2 times per week.

The patients’ responses indicated that applying imiquimod twice a week was safe and effective. Almost half, 45.1%, of the patients applying imiquimod had complete clearing of their treated AKs within 16 weeks. More than half, 59.1%, of the patients applying imiquimod twice a week for 16 weeks had 75% or more of their AKs clear. Expected side effects, such as redness, flaking/scaling/dryness, and scabbing/crusting, were tolerable.

Recently, researchers conducted clinical trials to find out if applying imiquimod three (3) times per week instead of two (2) times per week for 16 weeks would increase AK clearance and still be well tolerated. Here’s what they discovered:

• Clearance increases when imiquimod is used three (3) times per week; however, the gain is slight.
  
  The percentage of patients who achieved complete clearance increased by 3.2%. Patients experiencing a clearance rate of 75% or more within 16 weeks grew by 4.9%. These increases were much less than expected.
   

• More patients report local skin reactions when imiquimod is applied three (3) times per week to treat AKs.
  
  In this study, 40.9% of the patients applying imiquimod 3 times per week required a rest period. In other words, they had to stop using imiquimod for a period of time during the 16 weeks due to skin reactions.
   

• About 13% of patients completely discontinued using imiquimod due to skin reactions when they applied it 3 times per week.
   

• Overall, applying 5% imiquimod cream 3 times per week for 16 weeks proves safe and effective.
  
  However, when used 3 times per week, patients may experience more skin reactions and need a rest period from imiquimod during the 16 weeks.

Individual Response Varies
These clinical trials indicate that individual responses to imiquimod will vary and that some AKs do not clear with imiquimod. Many factors, including overall sun damage and how the patient’s immune system behaves, influence how a person responds. However, it is not yet known which factors can help predict how a patient will respond.

The researchers concluded that this study and others suggest the amount of imiquimod to be applied and the frequency may need to be individually tailored.

Is imiquimod right for you?
No one treatment is appropriate for every patient. If you believe that imiquimod may be right for you, speak with a dermatologist. There are many factors that a dermatologist considers before prescribing treatment for AKs. These include the size, number, and location of the AKs as well as the patient’s age and medical history. The patient’s willingness to avoid sun exposure, not use artificial tanning devices, and use the medication as directed at home also must be considered.

References:
Korman, N et al. “Dosing with 5% Imiquimod Cream 3 Times per Week for the Treatment of Actinic Keratosis.” Archives of Dermatology. 2005 April;141(4):467-73.

Lebwohl, M et al. “Imiquimod 5% cream for the treatment of actinic keratoses: Results from two phase III, randomized, double-blind, parallel group, vehicle-controlled trials.” Journal of the American Academy of Dermatology. 2004 May;50(5):714-21.

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