title: Inhibition of indomethacin crystallization in poly(vinylpyrrolidone) coprecipitates.
abstract: Differential scanning calorimetry and powder X-ray diffraction studies have been carried out with amorphous coprecipitates of indomethacin and poly(vinylpyrrolidone), PVP, to measure the glass transition temperature, Tg, as a function of mixture composition and the nonisothermal and isothermal crystallization of the indomethacin. Values of Tg as a function of mixture composition followed the ideal Gordon-Taylor equation up to about 50% w/w PVP. Inhibition of crystallization occurred at levels as low as 5% PVP and very significant inhibition was observed at and above 20% PVP. Inhibition of crystallization of indomethacin in the absence of PVP required a storage temperature 40-50 degrees C below Tg, whereas comparable inhibition with PVP was observed at storage temperatures 5 degrees C above Tg. This suggests that the inhibition of indomethacin crystallization by PVP may involve mechanisms other than just the general antiplasticizing effect (raising Tg) by PVP.
mesh_terms: D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D007213:Indomethacin / Q000737:chemistry*; D010968:Plasticizers / Q000737:chemistry; D011205:Povidone / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D010968:Plasticizers; D014867:Water; D011205:Povidone; D007213:Indomethacin