PHOTODEGRADATION OF INCLUSION COMPLEXES OF NAPROXEN AND NIFLUMIC ACID WITH β-CYCLODEXTRIN

M. Bogdan, C.Floare, Diana Bogdan, S. I. Farcas

National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania

The paper presents results of the studies on photochemical stability of naproxen (NAP) and niflumic acid (NIF) in their liquid inclusion complexes with β-cyclodextrin (β-CD). Formation of inclusion complexes was confirmed in aqueous solution by proton nuclear magnetic resonance spectroscopy (1H-NMR). The process of photodegradation was studied by UV spectrophotometry. Quantitative evaluation of the photochemical decomposition was performed on the basis of the calculated photoderadation rate constantm, k0, for the non-catalized reaction (i.e. in the absence of β-CD), k, the photodegradation rate constant of the guest in the form of inclusion complex and the stability constant Kst of the complex. Formation of the inclusion complexes of NAP and NIF with β-CD was proved to increase the photostability of the drugs. The nonlinear mathematical model used is particularly suitable for the study of cyclodextrin as a stabilizing system for compounds that are sensitive to light, oxygen, temperature or the media which contain them.