title: Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: a DSC study.
abstract: We report on the thermal behavior of freshly prepared binary drug/polymer physical mixtures that contained ibuprofen, ketoprofen, or naproxen as a drug, and polyvinylpyrrolidone (PVP), hydroxyethylcellulose (HEC), or methylcellulose (MC) as excipient. At 6-10 degrees C/min heating rates the DSC detected a sharp, single endotherm that corresponds to the melting of drug. On heating physical mixtures of PVP and racemic ibuprofen or ketoprofen at lower heating rates, another endotherm was registered in front of the original one. To observe the additional endotherm, specific minimal values of the heating rate and of PVP weight fraction were needed; for ibuprofen and ketoprofen they were 1.5 and 2.0 degrees C/min, and 5 and 15% (w/w), respectively. At greater PVP weight fractions the top temperatures, T(mp), of both peaks were reduced almost linearly indicating strong solid-state interfacial reaction between the drug particles and PVP matrix. The additional endotherm was abolished at greater heating rates (2 degrees C/min for ibuprofen, 3 degrees C/min for ketoprofen), by replacing the racemate with respective S+-enantiomer and by replacing PVP with HEC and MC. Hence, the possible inclusion of enantioselective component within the PVP/drug interaction, responsible for the amorphization of physical mixture over storage, is assumed.
authors.affiliation: Department of Physics, Biophysics, Roentgenology and Radiology, Medical Faculty, Thracian University, Stara Zagora, Bulgaria. ivanov_it@gbg.bg
authors.forename: Ivan T
authors.initials: IT
authors.lastname: Ivanov
authors.forename: Zhivka
authors.initials: Z
authors.lastname: Tsokeva
mesh_terms: D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D006358:Hot Temperature; D007052:Ibuprofen / Q000737:chemistry*; D007660:Ketoprofen / Q000737:chemistry*; D015394:Molecular Structure; D009288:Naproxen / Q000737:chemistry*; D011205:Povidone / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D009288:Naproxen; D007660:Ketoprofen; D011205:Povidone; D007052:Ibuprofen