The aim of this study is to determine the efficacy, safety and tolerability of either a once or twice daily topical application of LAS41007 compared to a twice daily application of LAS106521 in the treatment of actinic keratosis.

Inclusion Criteria:

• At least 4-10 clinically assessed actinic keratosis grade I to II (according to Olsen et al, 1991) in the face/forehead and/or on the bald scalp
• The diameter of each AK target lesion is not less than 0.5 cm and not greater than 1.5 cm
• The target lesions must be located in overall 2 treatment areas with a size of 25 cm2 per treatment area

Exclusion Criteria:

• Have evidence of clinically significant or unstable medical conditions such as:

  • metastatic tumor or tumor with high probability of metastatic spread
  • heart failure (NYHA class III or higher)
  • immunosuppressive disorder (e.g. HIV)
  • hematologic, hepatic, renal, neurologic or endocrine disorder.
  • collagen-vascular disorder (e.g. cerebrovascular disorder or other bleedings).
  • gastrointestinal disorder (e.g. active ulcera or history of recurrent peptic ulcera or hemorrhage)

• Suffer from paresthesia in the treatment areas

• Show Cornu cutaneum of the skin and/or hypertrophic AK lesions in the treatment areas