Journal
JOURNAL OF PHARMACEUTICAL SCIENCES
Volume 94, Issue 12, Pages 2591-2605Publisher
ELSEVIER SCIENCE INC
DOI: 10.1002/jps.20469
Keywords
solid state NMR; spectroscopy; amorphous; polymorphism; relaxation time; thermal analysis; quantitation
Ask authors/readers for more resources
Although most drugs are formulated in the crystalline state, amorphous or other crystalline forms are often generated during the formulation process. The presence of other forms can dramatically affect the physical and chemical stability of the drug. The identification and quantitation of different forms of a drug is a significant analytical challenge, especially in a formulated product. The ability of solid-state C-13 NMR spectroscopy with cross polarization (CP) and magic-angle spinning (AUS) to quantify the amounts of three of the multiple crystalline and amorphous forms of the artificial sweetener neotame is described. It was possible to quantify, in a mixture of two anhydrous polymorphic forms of neotame, the amount of each polymorph within 1-2%. In mixtures of amorphous and crystalline forms of neotame, the amorphous content could be determined within 5%. It was found that the crystalline standards that were used to prepare the mixtures were not pure crystalline forms, but rather a mixture of crystalline and amorphous forms. The effect of amorphous content in the crystalline standards on the overall quantitation of the two crystalline polymorphic forms is discussed. The importance of differences in relaxation parameters and CP efficiencies on quantifying mixtures of different forms using solid-state NMR spectroscopy is also addressed. (c) 2005 Wiley-Liss, Inc. and the American Pharmacists Association.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available