Chemical instability of 5-aminolevulinic acid used in the fluorescence diagnosis of bladder tumours

Mercedes Novo*, Gereon Hüttmann, Heyke Diddens

*Corresponding author for this work
68 Citations (Scopus)


Aqueous solutions of 5-aminolevulinic acid (ALA) prepared for intravesical instillation in the framework of a clinical study on the fluorescence diagnosis of urothelial bladder cancer were found to be unstable. This chemical instability of ALA was studied in aqueous solution of 37°C as a function of concentration, pH and reaction time. Our investigations showed that the reaction of ALA is an irreversible process, which yields at least two reaction products in the pH range studied (pH lower than 8): the 2,5-(β-carboxyethyl)dihydropyrazine and the 2,5-(β-carboxyethyl) pyrazine. As a result of these studies, the conditions for the preparation of ALA solutions to be used for intravesical instillation were optimized: solutions of ALA in phosphate-buffered saline at a concentration of 0.18 M (3 g of ALA in 100 ml) neutralized to pH 5, were prepared and stored on ice until use. Solutions prepared under these conditions were stable and were used for fluorescence diagnosis of bladder tumours with successful results. The effect of the pH and the composition of the urine on the extent of the reaction of ALA and on the nature of its reaction products formed during instillation was investigated by comparing the urine of patients before and immediately after instillation of ALA.

Original languageEnglish
JournalJournal of Photochemistry and Photobiology B: Biology
Issue number2-3
Pages (from-to)143-148
Number of pages6
Publication statusPublished - 07.1996

Research Areas and Centers

  • Academic Focus: Biomedical Engineering


Dive into the research topics of 'Chemical instability of 5-aminolevulinic acid used in the fluorescence diagnosis of bladder tumours'. Together they form a unique fingerprint.

Cite this