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Form III (form + iii)
Selected AbstractsSupercritical CO2 induced phase transition of Form III in isotactic poly-1-buteneASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Lei Li Abstract The effect of supercritical or high-pressure CO2 on the recrystallization of Form II in isotactic poly-1-butene (iPB-1) during the melting of Form III was investigated using high-pressure differential scanning calorimetry (DSC). The results showed that the recrystallization of Form II was inhibited by CO2. The crystal,crystal transition of Form III to I, in ambient nitrogen and supercritical CO2 was studied using fourier transform infrared spectroscopy (FTIR) and DSC. The results showed that CO2 promoted the phase transition and the transition proportion of Form III increased with the CO2 pressure increasing. Form III completely transformed into Form I, at 18 MPa. Moreover, supercritical CO2 could induce the amorphous region to transit into Form I,. The probable mechanism of the CO2 effects on Form III multiple transitions was also proposed. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Conformational polymorphism in aripiprazole: Preparation, stability and structure of five modificationsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2009Doris E. Braun Abstract Five phase-pure modifications of the antipsychotic drug aripiprazole were prepared and characterized by thermal analysis, vibrational spectroscopy and X-ray diffractometry. All modifications can be produced from solvents, form I additionally by heating of form X° to ,120°C (solid,solid transformation) and form III by crystallization from the melt. Thermodynamic relationships between the polymorphs were evaluated on the basis of thermochemical data and visualized in a semi-schematic energy/temperature diagram. At least six of the ten polymorphic pairs are enantiotropically and two monotropically related. Form X° is the thermodynamically stable modification at 20°C, form II is stable in a window from about 62,77°C, and form I above 80°C (high-temperature form). Forms III and IV are triclinic (), I and X° are monoclinic (P21) and form II orthorhombic (Pna21). Each polymorph exhibits a distinct molecular conformation, and there are two fundamental N,HO hydrogen bond synthons (catemers and dimers). Hirshfeld surface analysis was employed to display differences in intermolecular short contacts. A high kinetic stability was observed for three metastable polymorphs which can be categorized as suitable candidates for the development of solid dosage forms. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:2010,2026, 2009 [source] Solvent-mediated solid phase transformations of carbamazepine: Effects of simulated intestinal fluid and fasted state simulated intestinal fluidJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2009Paula Lehto Abstract Solvent-mediated transformations of carbamazepine (CBZ) anhydrate form III were investigated in Simulated Intestinal Fluid, a simple USP buffer medium, and in FaSSIF, which contains sodium taurocholate (STC) and lecithin, important surfactants that solubilize lipophilic drugs and lipids in the gastrointestinal tract. Raman spectroscopy (in situ) was utilized to reveal the connection between the changes in solid phase composition and dissolution rate while simultaneously detecting the solid state and the dissolved amount of CBZ. Initial dissolution rate was clearly higher in FaSSIF, while the solid phase data revealed that the crystallization of CBZ dihydrate was inhibited in both the dissolution media, albeit by different mechanisms. In SIF this inhibition was related to extensive needle growth, which impeded medium contact with the solid surface by forming a sterical barrier leading to retarded crystallization rates. Morphological changes from the needle-like dihydrate crystals to plate-like counterparts in FaSSIF, combined with the information that the transformation process was leveled off, evidenced strong hydrogen bonding behavior between the CBZ and STC molecules. These results underline the importance of biologically representative dissolution media in linking the in vitro dissolution results of solids that are capable of hydrate formation to their in vivo dissolution behavior. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:985,996, 2009 [source] | ||||||||||