Amorphous Indomethacin

Fig. 6 Water vapor sorption isotherm for crystalline and amorphous samples of indomethacin. ( ) Amorphous ( ) crystalline. (From Ref. " l)...

The possibility of different chemical behaviour of polymorphic modifications has been explored before only in the case of indomethacine amorphous and crystal forms reacted with ammonia by StoweU, Griesser, Bym et al. [62]. We have investigated two rather different systems, namely the polymorphic forms of barbituric acid [63] and of ferrocene dicarboxylic acids [64], which have been reacted with... 

Liu, Q. and G. Zogra. 1998. Phase behavior of binary and ternary amorphous mixtures containing indomethacin, citric acid, and PVPharm ReSl5 1202-1206. 

Taylor, L. S. and G. Zogra. 1997. Spectroscopic characterization of interactions between PVP and Indomethacin in amorphous molecular dispersi[Pg.528]

Carstensen JT, Morris T. Chemical stability of indomethacin in the solid amorphous and molten states. J Pharm Sci 1993 82 657-659. 

The combination of solid-state ATR-IR and solid-state NMR data supported the conclusion that the presence of crystalline material was responsible for changes in the dissolution profiles of the different lots. The results appear consistent with historical examples of changes in API physical form of solid, high molecular weight, polyethylene glycol dispersion formulations of amorphous indomethacin and griseofulvin (92-95). 

Andronis, V. and Zografi, G. (2000). Crystal nucleation and growth of indomethacin polymorphs from the amorphous state. J. Noncryst. Solids, 271, 236 8. [252] Anex, B. G. (1966). Optical properties of highly absorbing crystals. Mol. Cryst., 1, 1-36. [226]... 

Amorphous materials typically have a higher rate of dissolution and a higher kinetic solubility that their crystalline counterparts (Fig. 1). These characteristics can be exploited to enhance the rate and extent of absorption of poorly water-soluble APIs from the gastrointestinal tract. Such formulation approaches have been described for many APIs including indomethacin, griseofulvin, and several barbiturates. ... 

Fig. 1 Aqueous solubility of the amorphous and crystalline forms of indomethacin. (From Ref...

Fig. 7 Glass transition vs. water content relationship for amorphous indomethacin. Lines show fit to the Gordon-Taylor equation with K values of 0.33 (predicted) and 0.11...

Andronis, V. Yoshioka, M. Zografi, G. Effects of sorbed water on the crystallization of indomethacin from the amorphous state. J. Pharm. Sci. 1997, 86 (3), 346-351. 

Andronis, V. Zografi, G. The molecular mobihty of supercooled amorphous indomethacin as a function of temperature and relative humidity. Pharm. Res. 1998, 15 (6), 835-842. 

Crowley, K.J. Zografi, G. Cryogenic grinding of indomethacin polymorphs and solvates assessment of amorphous phase formation and amorphous phase physical stability. J. Pharm. Sci. 2002, 91, 492-507. 

Crystallinity of the particles. For example, amorphous form of indomethacin is more soluble than the crystalline one. ... 

Watanabe, T. Wakiyama, N. Usui, E. Ikeda, M. Isobe, T. Senna, M. Stability of amorphous indomethacin compounded with silica. Int. J. Pharm. 2001, 226, 81-91. 

The pathways of polymorphic transitions for cephalexin, chloramphenicol palmitate, and indomethacin have been studied, and the composition of partially transformed samples determined by XRPD.27 The metastable forms of chloramphenicol palmitate were found to transform into the stable phase when found at room temperature, confirming the results of a previous study.28 In contrast, cephalexin became amorphous upon grinding. Indomethacin exhibited the interesting behavior of becoming amorphous when ground at 4°C, but could be transformed into a metastable phase when ground at 30°C. 

Taylor LS and Zografi G. Spectroscopic Characterization of Interactions between PVP and Indomethacin in Amorphous Molecular Dispersions. PharmRes 1997 14 1691-1698. 

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