Definition

The hydrochloride salt form of aminolevulinic acid, an aminoketone, used for local photosensitizing therapy. Aminolevulinic acid (ALA) is a metabolic pro-drug that is converted into the photosensitizer protoporphyrin IX (PpIX), which accumulates intracellularly. Upon exposure to light of appropriate wavelength (red, or blue), PpIX catalyzes oxygen to singlet oxygen, an intracellular toxin, which can further react to form superoxide and hydroxyl radicals. This leads to cellular cytotoxic effects.