Acta Pharm. 63 (2013) 305-334
Methods of amorphization and investigation of the amorphous state
TOMAŽ EINFALT, ODON PLANINŠEK and KLEMEN HROVAT
University of Ljubljana, Faculty of Pharmacy, 1000 Ljubljana, Slovenia
Accepted April 26, 2013
The amorphous form of pharmaceutical materials represents the most energetic solid state of a material. It provides advantages in terms of dissolution rate and bioavailability. This review presents the methods of solid-state amorphization described in literature (supercooling of liquids, milling, lyophilization, spray drying, dehydration of crystalline hydrates), with the emphasis on milling. Furthermore, we describe how amorphous state of pharmaceuticals differ depending on method of preparation and how these differences can be screened by a variety of spectroscopic (X-ray powder diffraction, solid state nuclear magnetic resonance, atomic pairwise distribution, infrared spectroscopy, terahertz spectroscopy) and calorimetry methods.
Keywords: amorphous solid preparation, crystallinity, spectroscopy, calorimetry