A drug used to treat actinic keratosis (a skin condition that may become cancer). The drug is also being studied in the treatment of squamous cell and basal cell skin cancers and other types of cancer. When Levulan Kerastick is taken up by cells, including cancer cells, and then exposed to certain types of light, it becomes active and kills the cells. It is a type of photosensitizing agent. Also called aminolevulinic acid hydrochloride and Levulan.