Photodynamic activity of liposome‐delivered Cd‐texaphyrin using tumor‐bearing nude mice

Photodynamic effects in bladder‐tumor bearing nude mice induced by a krypton ion laser (752.5 nm) after i.v. application of liposome‐delivered cadmium texaphyrin were investigated. Cd‐texaphyrin possesses strong absorption transitions in the far red spectral region (around 760 nm) and a high quantum efficiency of singlet oxygen production. No therapeutic effects were obtained using irradiation 24 hours after administration of the sensitizer, whereas phototreatment 2 hours after application led to significant tumor reduction. This corresponds well with studies on fluorophore‐labeled liposomes indicating highest tumor accumulation 1–2 hours after administration. However, the induced cytotoxic effects were lower than those of HpD. © 1993 Wiley‐Liss, Inc.