ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 27 April 2007
Page Count: 8

Fast Scan Differential Scanning Calorimetry Distinguishes Melting, Melting-Degradation/Sublimation and Thermal Stability of Drugs

Riga, Alan T.
Cleveland State University, Cleveland, OH
College of Pharmacy, University of Toledo, Toledo, OH

Golinar, Michael
TA Instruments, New Castle, DE

Alexander, Kenneth S.
College of Pharmacy, University of Toledo, Toledo, OH

(Received 7 March 2006; accepted 15 February 2007)

Abstract

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 endohyphtherm with heating rate. The USP thermally stable standards evaluated in this study include vanillin (melt temperature, T_m, 80.4°C), acetanilide (T_m, 114°C), acetophenetidin (T_m, 135°C), sulfanilamide (T_m, 165°C), sulfapyridine (T_m, 191°C), and caffeine (T_m, 235°C and T_sublimation, <220°C). In addition to the USP samples a number of commercial and model drugs, like benzoic acid (T_m, 122°C and T_sublimation, <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
DOI: 10.1520/JAI100528
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