Powders physical stability

Ward, G. H., and Schultz, R. K. (1995), Process-induced crystallinity changes in albuterol sulfate and its effect on powder physical stability, Pharm. Res., 12,773-779. 

P. York, A preliminary study of the physical stability of tablets prepared from powders stored under tropical conditions. Pharm., 31 (1976) 383. 

Clark, A. R., Dasovich, N., Gonda, I., and Chan, H. K. The balance between biochemical and physical stability for inhalation protein powders rhDNAse as an example, in Proceedings of Respiratory Drug Delivery V. Buffalo Grove, IL Interpharm Press, 1996. 

A distinction must be made between chemical and physical stability. While physical stability is important, particularly in the evaluation of solid propellants, the chemical stability is of prime importance in the estimation of the course of decomposition of nitrate esters. The nitrate esters which are processed for use as propellants - unlike nitro compounds, which are relatively stable under these conditions - undergo a steady decomposition, which is due to imperfect purification of the starting materials and to the effect of other parameters such as temperature and air humidity. The rate of this decomposition is auto-catalyzed by the acidic decomposition products and may in certain cases produce spontaneous ignition. In order to reduce the decomposition rate as much as possible, suitable stabilizers are added to the powders, which are capable of accepting the acid cleavage products with formation of the corresponding nitro compounds (- Stabilizers). The stability is controlled by means of several tests (- Hot Storage Tests). 

Powder color, texture, particle size, fill weight, smell, case of reconstitution, reconstitution volume, viscosity, taste, color stability after reconstitution, and physical stability of suspension are critical blinding parameters. 

Ohta KM. Fuji M, Chikazawa M. Effect of geometric structure of flow promoting agents on the flow properties of pharmaceutical powder mixture. Pharm Res 2003 20(5) 804—9. Swaminathan V. Kildsig D. The effect of particle morphology on the physical stability of pharmaceutical powder mixtures The effect of surface tou ness of the carrier on the stability of ordered mixtures. Drug Dev Ind Pharm 2000 26(4) 365. 

Chan HK. Clark AR, Feeley J. etal. Physical stability of. salmon calcitonin spray-dried powders for inhalation. J Pharm Sci 2004 93 792-804. 

Forb RT. Davis KG, Hindlc M, Clarke JG, Mass J. Water vapor sorption studies on the physical stability of a series of spray-dried protein/sugar powders for inhalation. J Pharm Sci 1998 87 1316-21. 

Some aluminosilicate minerals appear to meet the above criteria rather well, especially with regard to low leachability and chemical and physical stability 1, 2). A low-temperature process for converting the wastes to aluminosilicates with low leachability has now been found (3). Aqueous waste solutions containing NaOH, NaNOa, NaN02, NaAl02, mixed fission products, and minor amounts of other salts are mixed with powdered clays (kaolin, bentonite, halloysite, or dickite) and allowed to react at 30°-100°C to form small crystals of the mineral cancrinite. The sodium aluminosilicate crystal lattice of cancrinite contains large amounts of trapped salts and radioactive fission products. The process is applicable to caustic radioactive liquids such as neutralized Purex wastes or to salts or oxides produced by evaporation or calcination of these liquid wastes. 

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