5aminolevulinic

5-aminolevulinic acid (5-ALA) is a naturally occurring amino acid that serves as a key precursor in the heme biosynthesis pathway. In cells, ALA is normally formed in mitochondria from glycine and succinyl-CoA by the enzyme ALA synthase and is further processed through porphyrin intermediates to heme. When given exogenously, 5-ALA acts as a prodrug that leads to accumulation of protoporphyrin IX (PpIX), especially in malignant and dysplastic tissues where the porphyrin synthesis pathway is altered.

The clinical relevance of 5-ALA lies in photodynamic therapy and fluorescence-guided surgery. PpIX is a photosensitizer; upon exposure to light, it generates reactive oxygen species that can kill cells. In dermatology and oncology, topical or oral 5-ALA is used to induce PpIX in target tissues, enabling destruction of abnormal cells when activated by specific wavelengths of light. In neurosurgery and certain oncologic procedures, oral 5-ALA is used to cause tumor tissues, such as gliomas, to fluoresce under blue light, aiding resections. Brand-name products include topical formulations for actinic keratoses and systemic preparations used for fluorescence-guided tumor surgery in some regions.

Administration routes and timing depend on the indication: topical or oral applications are common, with light activation occurring several hours after administration to allow PpIX accumulation. Side effects are largely related to photosensitivity; patients must avoid strong light exposure for an extended period after dosing. Caution is advised in individuals with porphyria or during pregnancy.