Encapsulation of nabumetone by means of -drug: (β-cyclodextrin)2:polyvinylpyrrolidone ternary complex formation

Abstract

[EN]The aim of the present study was to investigate the effect of the presence of the water-soluble polymer polyvinylpyrrolidone (PVP) MW=24,000 g/mol, on the complexing of the anti-inflammatory drug nabumetone, with β-cyclodextrin (β-CD). The data show that the polymer interacts with the free nabumetone and with the nabumetone:β-CD inclusion complex, in both cases with a stoichiometry of 1:1. The interaction constants are 1.3×104 M-1 and 1.6×104 M-1, respectively. The presence of PVP, changes the drug:cyclodextrin interaction, a nabumetone:(β-CD)2:PVP complex being formed. In addition, the presence of PVP, produces a strong increase in the global binding constant, β2=(22.12±0.22)×106 M-2 at 1% PVP. In the ternary complex, the nabumetone is wrapped at both ends for the β-CD. In this complex the polymer seems to act as a bridge between both β-CD molecules that bind the nabumetone.