New drugs and future developments in photodynamic therapy.

New photosensitizing drugs are becoming available which should improve on some of the disadvantages of haematoporphyrin derivates for photodynamic therapy (PDT). The main features are shorter duration of systemic photosensitisation, activation by longer and more penetrating light and better tumour to normal tissue drug uptake ratios. These drugs together with better understanding of in vivo light dosimetry promise to improve both results and clinical acceptability for PDT in future studies.