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Acid-sensitive Compounds (acid-sensitive + compound)
Selected AbstractsThe effect of bulking agents on the chemical stability of acid-sensitive compounds in freeze-dried formulations: Sucrose inversion studyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2009Enxian Lu Abstract The goal of the study was to evaluate the impact of amorphous bulking agents on the chemical stability of freeze-dried materials. Polyvinylpyrrolidone and dextran of different molecular weights and lactose were used as bulking agents, and sucrose was used as an example of an acid-sensitive compound. Lyophiles containing bulking agent and sucrose at 10:1 (w/w) ratio, citrate buffer, and optionally bromophenol blue (pH indicator) were tested by X-ray powder diffractometry, differential scanning calorimetry, and Karl Fischer titrimetry. Diffuse reflectance UV,vis spectroscopy was used to obtain the concentration ratio of the deprotonated (In2,) to the protonated (HIn,) indicator species, from which the Hammett acidity function (H2,) was calculated. The extent of sucrose inversion in lyophiles stored at 60°C was quantified by HPLC. The bulking agent had a major impact on both the apparent solid-state acidity (H2,) and the degradation rate, with the degradation rate constants value highest for dextran lyophiles (most "acidic", lower H2,) followed by lactose and polyvinylpyrrolidone lyophile (least "acidic", higher H2,). The Hammett acidity function can be used as an empirical solid-state acidity scale, to predict the rank-order stability of acid-sensitive compounds in lyophiles prepared with different bulking agents. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3387,3396, 2009 [source] An electrospray mass spectrometric method for accurate mass determination of highly acid-sensitive phosphoramiditesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2008Zoltán Kupihár An accurate mass determination method utilizing electrospray ionization mass spectrometry is described for analysis of several different types of phosphoramidites that are extremely acid-sensitive compounds. An earlier method, which applied a LiCl/acetonitrile system, was extended for this special application by using polymeric standards including poly(ethylene glycol) (PEG), poly(ethylene glycol) dimethyl ether (PDE) and poly(propylene glycol) (PPG). Concentrations of standards, samples and LiCl were optimized and potential impurities that affect the analyses were also investigated. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||