Pharmacokinetics of 5-aminolevulinic-acid-induced porphyrins in tumour-bearing mice.
Photodynamic therapy and photodynamic diagnosis help to support efficient treatment of superficial and early-stage cancer. During the last few years, 5-aminolevulinic acid (5-ALA), a precursor of haemoglobin in the haem biosynthetic pathway, was used to stimulate endogenous porphyrin production. In the following the time dependence of 5-ALA-induced porphyrin concentration will be investigated on several tissues in an in-vivo tumour model. 5-ALA was administered intravenously at a concentration of 50 mg-1 body weight. According to a certain time schedule the animals were sacrificed and 12 different organs as well as the tumour were removed. During excitation with the violet light of a Kr+ laser, porphyrin fluorescence spectra in the range 550-750 nm could be detected on the tissue samples. The intensity of the emission spectra at lambda = 635 +/- 2 nm was taken as a measure of the porphyrin concentration. All tissues showed porphyrin fluorescence. Brightest fluorescence was found on the tumour. A maximum contrast of the fluorescence intensity between the tumour and the non-malignant organs of up to 30 was observed at 4-6 h post-injection. The kinetics of the porphyrin concentration depend on the organ. Simple mathematical models will be derived and discussed.
Sroka
R
R
Laser-Forschungslabor an der Urologischen Klinik of the University of Munich, Germany.
Beyer
W
W
Gossner
L
L
Sassy
T
T
Stocker
S
S
Baumgartner
R
R
D000622:Aminolevulinic Acid / Q000493:pharmacokinetics*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007275:Injections, Intravenous; D051379:Mice; D008812:Mice, Hairless; D008954:Models, Biological; D009369:Neoplasms / Q000378:metabolism*; D010778:Photochemotherapy; D011166:Porphyrins / Q000378:metabolism*; D013997:Time Factors
D011166:Porphyrins; D000622:Aminolevulinic Acid