Characterization of a new photosensitizer (13(2)-hydroxy- bacteriopheophorbide-a methylester) for future treatment of ovarian carcinoma (an experimental study).

UNLABELLED

The photosensitizer 132-hydroxy bacteriopheophorbide-a methyl ester (13(2) OH- BPME) is characterized by a high absorption coefficient at the far red wavelength 750 nm and a good singlet oxygen quantum yield.

METHODS & RESULTS: The pharmacokinetics of 132-OH- BPME were studied in ovarian carcinoma on mice after i.v. administration of 7.8 micromole/kg body weight at different incubation intervals. The accumulated dye was chemically extracted from selected tissues and the concentrations were measured by absorption spectroscopy. The parenchymatous organs (liver, spleen and kidney) showed maximum 13(2)- OH- BPME concentrations after 2 hours incubation (liver, spleen), and 4 hours post injection (kidney). A high uptake was detected in the lung with maximum concentration at 2 hours. The malignant tissue accumulated high 13(2)- OH- BPME concentrations between 2-12 hours post injection with peaking at 8 hours. The 13(2)- OH- BPME concentrations in muscle tissue, representing the normal tumour surroundings, and in the skin were very low.

CONCLUSION

The results of our study suggest that PDT using 13(2)-OH-BPME could be effective at 8h post injection, where the tumour 13(2)- OH-BPME uptake is maximum and the muscle and skin uptake will be minimum.