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- Title
Solid-state mechanical properties of crystalline drugs and excipients.
- Authors
Thakur, Shravan; Maheswaram, Manik; Mantheni, Dhruthiman; Kaza, Lakshmi; Perara, Indika; Ball, David; Moran, John; Riga, Alan
- Abstract
Thermal mechanical analysis (TMA) of crystalline drugs and excipients in their pre-melt temperature range performed in this study corroborate their newly found linear dielectric conductivity properties with temperature. TMA of crystalline active pharmacy ingredients (APIs) or excipients shows softening at 30-100 °C below the calorimetric melting phase transition, which is also observed by dielectric analysis (DEA). Acetophenetidin melts at 135 °C as measured calorimetrically by DSC, but softens under a low mechanical stress at 95 °C. At this pre-melting temperature, the crystals collapse under the applied load, and the TMA probe shows rapid displacement. The mechanical properties yield a softening structure and cause a dimensionally slow disintegration resulting in a sharp dimensional change at the melting point. In order to incorporate these findings into a structure-property relationship, several United States Pharmacopeia (USP) melting-point standard drugs were evaluated by TMA, DSC, and DEA, and compared to the USP standard melt temperatures. The USP standard melt temperature for vanillin (80 °C) [], acetophenetidin (135 °C) [], and caffeine (235 °C) [] are easily verified calorimetrically via DSC. The combined thermal analysis techniques allow for a wide variety of the newly discovered physical properties of drugs and excipients.
- Subjects
PHENACETIN; CRYSTALS; EXCIPIENTS; SOLID state chemistry; STRUCTURE-activity relationship in pharmacology; PHARMACODYNAMICS; THERMAL analysis
- Publication
Journal of Thermal Analysis & Calorimetry, 2012, Vol 108, Issue 1, p283
- ISSN
1388-6150
- Publication type
Article
- DOI
10.1007/s10973-011-1859-0