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Volume 4, Issue 3
(March 2007)
ISSN: 1546-962X
Fast Scan Differential Scanning Calorimetry Distinguishes Melting, Melting-Degradation/Sublimation and Thermal Stability of Drugs In order to establish a structure and property (melting and oxidative or thermal degradation, or both) relationship for a United States Pharmacopeias (USP) set of standard drugs, they were evaluated by fast scan differential scanning calorimetry. A critical problem in characterizing the endothermic melting of a drug is to determine the melting range and if a chemical melts and immediately degrades. The stability of standard drugs is based on a comparison of their thermal properties at widely varying ramp or heating rates from 10 to 100°C/min. A stable crystalline drug has an obvious melting endotherm followed by a stable baseline. An unstable crystalline drug melts and immediately degrades as viewed by a shifting melt endotherm with heating rate. The USP thermally stable standards evaluated in this study include vanillin (melt temperature, , 80.4°C), acetanilide (, 114°C), acetophenetidin (, 135°C), sulfanilamide (, 165°C), sulfapyridine (, 191°C), and caffeine (, 235°C and , <220°C). In addition to the USP samples a number of commercial and model drugs, like benzoic acid (, 122°C and , <120°C), lidocaine.HCl and procaine.HCl were also examined. Their melt profiles were ranked as stable or unstable post fusion by the fast scan DSC technique and are reported.
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Paper ID: JAI100528 | ||
