Naproxen: Hydroxypropyl-β-cyclodextrin: 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 = 24000 g/mol, on the complexation of the phototoxic anti-inflammatory drug naproxen, in its sodium salt form, with hydroxypropil-β-cyclodextrin (HP-β-CD). The data show that the polymer interacts with the free naproxen and with the naproxen:HP-β-CD inclusion complex. The presence of different proportions of PVP, in the 0–1%(w/w) range systematically increased the Kapp of the naproxen:HP-β-CDinclusion complex formation. The cause of this increase is that the polymer interacts with the HP-β-CD with a binding constant of K2 = 29000± 53M−1; and with the naproxen:HP-β-CD inclusion complex, to give a ternary complex naproxen:HP-β-CD:PVP. The binding constant of this process was K3 = 5350 ± 1 M−1. NMR data revealed that in the ternary system, PVP is outside of the cyclodextrin, and therefore must be wholly or partially recovering the naproxen:HP-β-CD inclusion complex.