Abstract

Hexaminolevulinate (HAL) is a diagnostic agent that allows the visualization of tumor tissue in the bladder by fluorescence cystoscopy. It is administered intravesically via a catheter for 1 hour, followed by blue light bladder inspection to induce selective red tumor fluorescence. Hexaminolevulinate should ideally be confined to the bladder only, but it is likely that some absorption occurs during administration, and therefore the systemic bioavailability is of interest. The bioavailability of HAL was determined by intravesical and intravenous administration of 14C-HAL hydrochloride to 8 human volunteers. To reduce the radiation dose as low as possible, the ultrasensitive analytical technique of accelerator mass spectrometry was used to measure 14C-HAL. The bioavailability of 14C-HAL after intravesical and intravenous administration was determined from the respective area under the curve based on total radioactivity and was determined to be 7% (range, 5%-10%; 90% confidence interval). The systemic absorption of 14C-HAL after intravesical administration is low and supports previous clinical experience with HAL showing no systemic side effects. ©2006 the American College of Clinical Pharmacology.