ISSN: 1546-962X
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.

Golinar, Michael
TA Instruments, DE

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

Keywords:

Paper ID: JAI100528
DOI: 10.1520/JAI100528
ASTM International is a member of CrossRef.