Photodynamic and Sonodynamic Therapy

Most clinically used PDT sensitizers are metal-free porphyrins and porphyrin derivatives such as 56. Hematoporphyrin and its deriva- 

The lutetium complex 57 is currently under clinical evaluation as a photosensitizer for the treatment of cancer. This complex possesses a strong broad absorption band centered at 732 nm (247). Upon absorption of light, 57 becomes activated to a long-lived triplet state and reacts with 302 to generate cytotoxic. Complex 57 is also on clinical trial as a photosensitizer for the treatment of atherosclerisis, a vascular disease caused by deposition of cholesterol and other fatty materials in the walls of blood vessels. 

Several other metal complexes have promising photodynamic activity and are currently under development (248). Metalloporphyrins inhibit the enzyme heme oxygenase for example, chromium porphyrin and mesoporphyrin are potent inhibitors of heme oxygenase both in vitro and in vivo (249, 250) and are being used for the treatment of the neonatal jaundice. 

Tin(IV) ethyl etiopurpurin 58 (SnET2) (251) is a second-generation photosensitizer currently under clinical evaluation (242). Once delivered to blood plasma, complex 58 interacts with lipoproteins and preferentially binds to high-density lipoproteins (252). The aggregation of 58 is slow and it binds to lipoproteins as a monomer (253). 

Tin(IV)-protoporphyrin (254), Ga-deuteroporphyrin (255), and Co-mesoporphyrin (256) complexes are potent inhibitors of heme oxygenase. The Sn(IV) complex significantly inhibits bilirubin production 

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