Effect of the structure and concentration of cyclodextrins in the quenching process of naproxen

The effect of the formation of the naproxen:cyclodextrin inclusion complex on the quenching of the drug by iodide has been studied. The results show that α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), and hydroxypropyl-β-cyclodextrin (HP-β-CD) provide good protection for the drug against iodide quenching. The trend of protection is α-CD > HP-β-CD ≈ β-CD > H2O, in contrast to the binding constant values and the structure of these complexes. The effect of these cyclodextrins on the quenching process is discussed on the basis of the parameters obtained by fitting the experimental data to the modified Stern–Volmer, and finite-sink approximation models.