Chapter 14: Singlet Oxygen Generation by Drugs and Their Metabolites

Photosafety is becoming an important issue to take into account in drug development. In this context, a deep knowledge of drug photoreactivity is necessary to understand the photobiological properties and to anticipate the appearance of photosensitivity side effects. In the present chapter, the capability to photoinduce singlet oxygen is summarized for the most relevant families of drugs like nonsteroidal anti-inflammatory drugs, antibacterial quinolones, statins and phenothiazines, among others. In some cases, the properties of drug photoproducts and metabolites are also given. From the critical examination of the existing data, it becomes clear that singlet oxygen may indeed mediate photosensitized oxidation of biomolecules by some therapeutic drugs, although this process seems to be efficient (Φ_Δ > 0.2) in a relatively limited number of cases.