Possible advantages of aluminum-chloro-tetrasulfonated phthalocyanine over hematoporphyrin derivative as a photosensitizer in photodynamic therapy.

The potency of aluminum-chloro-tetrasulfonated phthalocyanine (AlS4Pc) as a photosensitizer in photodynamic therapy was evaluated in in vitro and in vivo studies. Compared with hematoporphyrin derivative (HpD), the following advantages of AlS4Pc were revealed: (1) AlS4Pc was less toxic than HpD in vitro without light irradiation. (2) AlS4Pc showed more photodynamic-dependent cytotoxicity and anti-tumor effect in the red area of the spectrum (> 660 nm) at which tissue penetration is high. (3) AlS4Pc appeared to be removed more rapidly from normal tissues such as muscle and skin. (4) AlS4Pc showed less photodynamic-dependent cytotoxicity in vitro and milder cutaneous phototoxicity in vivo with UVA irradiation. On the basis of these observations, AlS4Pc shows considerable promise as a photosensitizer for PDT.