Chemical stability studies

Chemical stability studies wiU also be conducted on aqueous solutions of the drug at varying pHs and temperatures and in a variety of solvents, experiments that may be coupled with determination of solubility. This information is important for determining the shelf life... 

Golakoti T, Ogino J, Heltzel CE, Husebo TL, Jensen CM, Larsen LK, Patterson GML, Moore RE, Mooberry SL, Corbett TH, Valeriote FA (1995) Structure Determination, Conformational Analysis, Chemical Stability Studies, and Antitumor Evaluation of the Cryptophycins. Isolation of 18 New Analogs from Nostoc sp. Strain GSV 224. J Am Chem Soc 117 12030... 

Orberholtzer, E. R., Brenner, G. S. Cefoxitin sodium solution and solid-state chemical stability studies. J Pharm Sci 68 863-866 (1979). 

Chemical stability studies are monitored by silica gel thin-layer chromatography (tic) or by high performance liquid chromatography (hplc) using a reverse- Ph ase Clg coated column (24). Hplc peaks or dc spots are visualized by their uv absorption at 245 nm the dc spots can also be detected by ceric sulfate or phosphomolybdic acid staining. 

To evaluate polymorph changes and can be combined with stress chemical stability studies... 

Mvo-inositol 1,4-diphosphate (38), the racemate of a metabolite of second messenger myo-inositol 1,4,5-triphosphate and its diphosphorothioate analogue (39) have been synthesised from f 1 -1 2.4 S-di-O-isopropylidene-mvo-inositol by way of phosphite intermediates. Similarly, (-mvo-inositol 1,3,4-triphosphate has been obtained from f W2.4.S-tri-O-benzyl-myo-inositol Phosphite chemistry was also employed in the preparation of diphosphorylated and diphosphonylated Lipid A monosaccharide analogues (40). Related Lipid A components are mentioned in Chapter 9. Methyl 3-deoxv-a-D-manno-oct-2-ulopyranosidonic acid 4-phosphate has been synthesised and its chemical stability studied. ... 

This capability for measuring chemical degradation over relatively short observation periods may prove to be an extremely powerful analytical technique that could greatly support conventional chemical stability studies or in some cases replace them altogether. The use of isothermal microcalorimetry in the study of chemical stability in the solution phase is relatively straightforward. The sample is placed in the reaction ampoule and measurements are made. However the difficulty arises in interpretation of the data and, in particular, with reaction kinetics. This is reflected in the literature where attempts to analyse reaction kinetics are normally reserved for first order reactions that are relatively easy to solve. However, there are some promising methods for data analysis which may be divided into three categories. The choice of method depends on the information required from the study. 

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