NECROSIS OF MURINE TAIL SKIN FOLLOWING PHOTODYNAMIC TREATMENT WITH meso‐tetra‐(p‐SULPHOPHENYL) PORPHINE (TPPS)

Albino mice were injected intravenously with 2 mg of meso‐tefra‐(p‐sulphophenyl) porphine (TPPS) and subsequently their tails were exposed to a range of doses of full‐spectrum visible light. At a power density of 75 mW cm‐2, a 50% incidence of gross necrosis of the tail skin (ED50) occurred at a light dose of 130 J cm‐2. For haematoporphyrin derivative at the same administered dose, the ED50 was 33 J cm‐2. Increasing the interval between TPPS and light from 1 to 34 days did not spare the tail skin, in terms of an increase in ED50. The slopes of curves of incidence of tail necrosis vs light dose were steep: 1/slope ranged between 20 and 50 J cm‐2.