The presence of the AIDS virus in the blood supply caused a major change in the way we treat blood and products derived from it (plasma, proteins, platelets and red blood cells). Conventional methods of viral inactivation in plasma fractions were based on irradiation or treatment with detergents, but this is not applicable to cellular blood fractions due to collateral damage.

The use of photoactivable chemicals as antiviral agents in the blood industry is currently undergoing a rapid expansion. Photochemical agents based on the psoralen nucleus may be employed for viral inactivation in plasma and platelets, but endogenous haem absorption complicates their use in red blood cell concentrates and long wavelength absorbing photosensitizers based on the phenothiazine or phthalocyanine chromophores are more likely to be of commercial importance in this particular field.

The chemistry, photochemistry and cellular effects of the various agents are discussed, along with future prospects for this exciting area of medicine.