Aminolaevulinic acid

A topically administered metabolic precursor of protoporphyrin IX. After topical administration, aminolevulinic acid (ALA) is converted to protoporphyrin IX (PpIX) which is a photosensitizer. When the proper wavelength of light activates protoporphyrin IX, singlet oxygen is produced, resulting in a local cytotoxic effect. (NCI04)