Study on the Efficacy of LAS41005 in the Treatment of Actinic Keratosis

Main Inclusion Criteria: * Have at least 4 but not more than 10 clinically confirmed AK target lesions of mild to moderate intensity within the face/forehead or bald scalp (excluding eyelids, lips, and mucosa), i.e. actinic keratosis grade I and II according to Olsen EA et al. 1991 * Woman of childbearing potential are allowed to participate in this study only if they use a highly effective method of contraception Main Exclusion Criteria: * Have received effective treatment of AK in the three months preceding this clinical trial * Have known hypersensitivity to LAS41005 or LAS106521 * Have currently other malignant or benign tumors of the skin within the treatment area (e.g. malignant melanoma, basal cell carcinoma, squamous cell carcinoma) * Patient's taking phenytoin * Show cornu cutaneum like alterations of the skin in the face or the bald scalp (target area)