Drug–excipient interactions in ketoprofen: A vibrational spectroscopy study

Ketoprofen (3‐benzoyl‐α‐methylbenzeneacetic acid) is a widely used nonsteroidal anti‐inflammatory drug (NSAID), always administered in the form of drug–excipient physical mixtures (PMs). The occurrence of possible interactions between ketoprofen and two commonly used excipients—lactose (LAC) and polyvinylpyrrolidone (PVP)—was evaluated, through vibrational spectroscopy techniques [both Raman and Inelastic Neutron Scattering (INS)]. Spectral evidence of drug:excipient close contacts, which were enhanced by aging, was verified for the (1:1) (w:w) (ketoprofen:PVP) and (ketoprofen:LAC) PMs, both by Raman and INS. These interactions were found to involve mainly the central carbonyl and the terminal methyl‐carboxylic moieties of the ketoprofen molecule, this being reflected in particular vibrational modes, such as the methyl torsion, the out‐of‐plane COH bending, and the inter‐ring CO stretching. © 2006 Wiley Periodicals, Inc. Biopolymers 82: 420–424, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com