5-Aminolaevulinic acid (ALA) and its ester derivatives are used in photodynamic therapy. Despite extensive investigations, the differences in biodistribution and pharmacokinetics of protoporphyrin IX (PpIX) induced by ALA and its derivatives are still not well understood, notably for humans.
Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, 0310 Montebello, Oslo, Norway. asta.juzeniene@klinmed.uio.no