Photodegradation of Nabumetone in n-butanol solutions

Abstract

[EN]The photolability of the anti-inflammatory drug Nabumetone was studied in n-butanol. The photoproducts were followed by UV-Vis absorption, fluorescence and FTIR spectroscopies as well as gas chromatography–mass spectrometry (GC/MS). The photodegradation process in this organic medium followed first-order kinetics. In contrast with what was expected on the basis of the changes in the electronic spectra observed, the process seems to be more efficient than in water, with a Φ = 0.47 and a half-life, t1/2 = 3.0min, leading to different products. In this medium, the side chain is photo-oxidised to 6-methoxy-2-naphthaldehyde, as a major product. In addition the (4-(6-methoxy-2- naphthyl)-3-buten-2-one) was detected. The kinetic behaviour suggests that the photoproducts are formed from the singlet excited state (1NB∗) of the drug. Therefore the increase in the rate constant of the degradation of the Nabumetone, may be thought to be due to an increase in the concentration of this excited species via hydrogen bond formation with the solvent.