5-Aminolevulinic acid hexyl ester

V - Various

QV - Various

In vitro studies have shown increased porphyrin fluorescence in normal urothelium after exposure to hexaminolevulinate hydrochloride intravesical solution. In the human bladder, a greater accumulation of porphyrins is proposed in neoplastic or inflamed cells, compared to normal urothelium. After bladder instillation of hexaminolevulinate hydrochloride intravesical solution for approximately 1 hour and subsequent illumination with blue light at wavelengths 360 – 450nm, the porphyrins will fluoresce red.

Hexaminolevulinate is an ester of the heme precursor, aminolevulinic acid. After bladder instillation, hexaminolevulinate enters the bladder mucosa and is proposed to enter the intracellular space of mucosal cells where it is used as a precursor in the formation of the photoactive intermediate protoporphyrin IX (PpIX) and other photoactive porphyrins (PAPs). PpIX and PAPs are reported to accumulate preferentially in neoplastic cells as compared to normal urothelium, partly due to altered enzymatic activity in the neoplastic cells. After excitation with light at wavelengths between 360 and 450 nm, PpIX and other PAPs return to a lower energy level by fluorescing, which can be detected and used for cystoscopic detection of lesions. The fluorescence from tumor tissue appears bright red and demarcated, whereas the background normal tissue appears dark blue. Similar processes may occur in inflamed cells.