Polymorphism investigation

Dudley C, Keavney B, Casadei B, Conway J, Bird R, Ratcliffe P. Prediction of patient responses to antihypertensive drugs using genetic polymorphisms investigation of renin-angiotensin system genes. J Hypertens 1996 14 259-262. 

Over the past few years, materials scientists have designed and conducted research to determine the stable form in the conditions of the formulated dosage form. Luthra et al. identified that the thermodynamically stable form, anhydrous crizotinib free base, converted to a qnatemary complex (API, phosphate, water, sucralose) in the formulated oral solution in which precipitation was observed [9]. This spurred the design of new solid form/polymorph investigation designated as the Formulation Form Screen. In this case as well as research published by Arora et al. [10, 11] and Bak et al. [12], unintended cocrystal formation occurred between the stable form of the API and the formulation components. As the number of variables and conditions exponentially increase as the stable API form is exposed to a formulated environment, there becomes a need to develop new approaches to test the reactivity of the API with its formulation components. 

Indeed, when CP/MAS has become routinely employed in SSNMR characterization of pharmaceutical compounds, there are other nuclei, less used than the former, that can bring important and unique information when studding drugs in sohd form. One of these nuclei is Cl. The nuclear quadrupole resonance (NQR) has been widely used for polymorphism analysis [101,102], and in the past years, the use chlorine nuclei also started to be used in SSNMR experiments for polymorphism investigation. The NMR is an excellent probe of the Cl ion-binding envi-... 

Peterson, V. K., B. A. Hunter and A. Ray (2004). Tricalcium Silicate T1 and T2 Polymorphic Investigations Rietveld Refinement at Various Temperatures Using Synchrotron Powder Diffraction . Journal of the American Ceramic Society 87 (9) 1625-1634. 

Oxides. Owing to the importance as nuclear fuel material, actinide oxides have been intensively investigated. These are very compHcated compounds because of the formation of non stoichiometric or polymorphic materials. Actinide oxides are very heat-resistant and Th02 is the highest... 

Chemical development Proof of structure and configuration are required as part of the information on chemical development. The methods used at batch release should be validated to guarantee the identity and purity of the substance. It should be established whether a drug produced as a racemate is a true racemate or a conglomerate by investigating physical parameters such as melting point, solubility and crystal properties. The physicochemical properties of the drug substance should be characterized, e.g. crystallinity, polymorphism and rate of dissolution. 

Numerous theoretical and experimental studies have dealt with the properties of rutile (see 3 and references therein), while the other polymorphs have attracted less attention. This is due to the fact that rutile is easier to grow and characterize, and has a simpler structure that can be readily investigated using a variety of theoretical techniques. The fact that the experimentally reported bulk modulus of anatase is in the range from 59 GPa to 360 GPa illustrates the need for further studies of titanium dioxide polymorphs. 

Brand-Herrmann SM, Kuznetsova T, Wiechert A et al (2005) European Project on Genes in Hypertension Investigators. Alcohol intake modulates the genetic association between HDL cholesterol and the PPARgamma2 Pro 12Ala polymorphism. J Lipid Res 46 913-919... 

The CP/MAS NMR spectra are an important source of information regarding the structure of cellulose and its polymorphos. A number of groups have investigated these spectra 11 15) and also reviews on the subject have been published 16 17>. For an orientation in the field Table 1 shows the most important features of the solid-state NMR spectra of cellulose I, II and IV and in Fig. 3 the numeration of the carbon atoms of the cellulose basic unit is given. It is evident that the polymorphs... 

Many of the investigated mesogenic compounds show solid state polymorphism. In order to obtain useful information about the arrangement of the molecules in the mesophase from the X-ray data of the single crystals, it is important to investigate the crystal structure of those solid phase which transforms into the liquid crystalline phase. For instance, only the crystal structures of the low temperature solid phases of the compounds MBBA [138, 139], MHPOBC [159], and T15 [81] could be determined, but the... 

The feasibility of synthesizing oxovanadium phthalocyanine (VOPc) from vanadium oxide, dicyanobenzene, and ethylene ycol using the microwave synthesis was investigated by comparing reaction temperatures under the microwave irradiations with the same factors of conventional synthesis. The efficiency of microwave synthesis over the conventional synthesis was illustrated by the yield of crude VOPc. Polymorph of VOPc was obtained ttough the acid-treatment and recrystallization step. The VOPos synthesized in various conditions were characterized hy the means of an X-ray dif actometry (XRD), a scanning electron microscopy (SEM), and a transmission electron Microscopy (TEM). 

Phospholipids are amphiphilic compoimds with high surface activity. They can significantly influence the physical properties of emulsions and foams used in the food industry. Rodriguez Patino et al. (2007) investigated structural, morphological, and surface rheology of dipalmitoylpho-sphatidylcholine (DPPC) and dioleoyl phosphatidylcholine (DOPC) monolayers at air-water interface. DPPC monolayers showed structural polymorphisms at the air-water interface as a function of surface pressure and the pH of the aqueous phase (Fig. 6.18). DOPC monolayers showed a... 

The surface phase diagram of vanadium oxides on Rh(l 11) has been investigated in a series of papers of our group [4, 18, 19, 90, 101-103]. It is characterized by pronounced polymorphism and many different oxide structures have been detected as a function of coverage and growth temperature. The vanadium oxide structures for coverages up to the completion of the first monolayer formed on Rh(l 11) under the different preparation conditions may be subdivided into highly oxidized phases... 

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