Actinometric and Φ-order photodegradation properties of anti-cancer Sunitinib.

The photodegradation reaction of Sunitinib (SUT), occurring via Z–E photoisomerization, has been evaluated in this study using the recently developed –order kinetics. In ethanol, the forward (Z E) photoreaction of SUT was invariant with irradiation (its quantum yield, 0.019) in contrast to the E Z isomerisation whose undergoes a 30‐fold, sigmoid–shaped, increase with increasing irradiation wavelength. This situation limited usefully the extent of Z– SUT photodegradation at the photostationary state to a maximum of c.a. 30 % of the initial concentration. Nevertheless, these results support a strong recommendation for a complete protection of SUT from light at all stages. Furthermore, a SUT‐actinometer was developed and was proven to be useful for the 320–480 nm spectral range. The latter wavelength interval defined as well SUT photodegradation causative range. The formalism of –order kinetics, proves to be a useful investigative tool for drugs’ photodegradation studies.