The purpose of this study is to determine if the new ingenol derivative gels are as safe as and as well tolerated as ingenol mebutate gel when applied to AK lesions on the forearm for two consecutive days.

Various concentrations of new ingenol derivatives will be applied to AKs on the forearms. Reactions and safety will be compared to a US registered and marketed ingenol gel to ascertain if the new ingenol is at least as safe and as well tolerated as the registered ingenol.

Inclusion Criteria:

• Must be male or female and at least 18 years of age.
• Female patients must be of non-childbearing potential or if of childbearing potential then negative serum and urine pregnancy test and using effective contraception
• Ability to provide informed consent

Exclusion Criteria:

• location of the selected treatment area within 5cm of an incompletely healed wound or within 5cm of a suspected basal cell carcinoma or squamous cell carcinoma
• undergone Cosmetic or therapeutic procedures within 2cm of the selected treatment area in the 2 weeks prior to Visit 2
• use of acid-containing therapeutic products within 2cm of the selected treatment area in the 2 weeks prior to Visit 2
• use of topical moisturisers/creams/lotions, artificial tanners or topical steroids within 2cm of the selected treatment areas in the 2 weeks prior to visit 2 Treatment with immunomodulators, or interferon/interferon inducers or systemic medications that suppress the immune system within 4 weeks of Visit 2
• Treatment with 5-FU, imiquimod, diclofenac, or photodynamic therapy within 2 cm of the treatment area in the 8 weeks prior to visit 2
• use of systemic retinoids
• those who are currently participating in any other clinical trial
• females who are pregnant or are breastfeeding
• those known or suspected of not being able to comply with the requirements of the protocol or provide consent