The solubility and viscosity of sugars (glucose, lactose, leucrose, maltose, raffinose, sucrose, and trehalose), polyols (maltitol, mannitol, sorbitol, and xylitol), and polysaccharides ( -cyclodextrin, dextrans, and inulin) in water and water-ethanol mixtures was investigated at 310 K. The increase in ethanol fraction caused a decrease in solubility in all cases. The viscosity of a 10 % (w/w) solution of any of those sugars was (1 to 1.25) mPa s except dextran solutions, which reached 5 mPa s. The viscosity of saturated solutions varied strongly from one compound to another even though the solubilities were similar. The metastable zone widths of sucrose, maltose, and lactose precipitated with ethanol were significantly larger than the one measured for mannitol. IntroductionData on the solubility and viscosity of sucrose and lactose in aqueous solution are widely available in the literature. [1][2][3][4][5] However, little information is available for many other sugars, polyols, and polysaccharides. [6][7][8][9] Even though the effect of ethanol on a few of these solutions has been investigated, 10-20 the information available is fragmented and limited to the most common sugars. Still, some work on the prediction of the solubility of sugars in water-ethanol mixtures was done using the basic and modified UNIFAC 21-24 and UNIQUAC models, 10,13,25 or the Redlich-Kister expansion model, 20 but only for some common small sugars: sucrose, glucose, and lactose.The addition of an antisolvent, such as ethanol, to an aqueous solution containing a solute poorly soluble in water would result in the precipitation of the solute by a process called antisolvent precipitation, dilution, salting-out, or drowning-out crystallization. Antisolvent precipitation investigation has been mainly devoted to kinetic studies under batch or continuous operations [26][27][28][29] or to the experimental and theoretical study of the influence of the process conditions on the particle size and shape. [29][30][31][32][33][34][35][36] Also, other data on crystallization-related parameters are scarce. Compared with other crystallization processes, limited information is available on the metastable zone width caused by the addition of antisolvent 34,37,38 during antisolvent precipitation.These physicochemical data are of interest in the fields of pharmaceutical formulation and food, where various sugars, polyols, and polysaccharides are commonly used. The properties measured in this study might then be required for the design of new processes. In this work, solubility, viscosity, and supersaturation measurements were conducted on various sugar, polyol, and polysaccharide solutions prepared with waterethanol mixtures at 310 K. Materials and MethodsMaterials. D-Saccharose (crystalline, Riedel-de Haen), lactose anhydrous (crystalline, Fluka), and D-mannitol (crystalline, Fluka) of European Pharmacopoeia grade, dextrose anhydrous (crystalline, glucose, Sigma) of USP grade, D-trehalose dihydrate (crystalline, Sigma), D-leucrose (+98 %) (crystalline, Fluka...

The solubilities of R-, -, and γ-glycine in aqueous solutions containing methanol, ethanol, 2-propanol, or acetone were measured at 310 K. The solubility of all the polymorphs dropped rapidly as a function of the concentration of antisolvent. The solubility of the glycine polymorphs in water-antisolvent mixtures was, in decreasing order: methanol > ethanol > 2-propanol > acetone. The solubility of R-glycine was slightly higher than that of γ-glycine, but the solubility of -glycine was significantly higher by up to 17 %. The induction time for the recrystallization of -to R-glycine in those water-antisolvent mixtures was, in decreasing order: methanol > ethanol > acetone > 2-propanol. This signifies that the selection of an antisolvent for preparation of -glycine can have an important effect on the product.

Therapeutic proteins have become essential in the treatment of many diseases. Their formulation in dry form is often required to improve their stability. Traditional freeze-drying or spray-drying processes are often harmful to labile proteins and could be replaced by supercritical fluid (SCF) drying to produce particles with defined physicochemical characteristics in a mild single step. A survey of the current SCF drying processes for proteins is presented to give insight into the effect of SCF drying on protein stability and to identify issues that need further investigation. Methods used for drying aqueous and organic protein solutions are described. In particular, effects of process and formulation parameters on particle formation and protein stability are discussed. Although SCF methodology for drying proteins is still in its infancy, it can provide a serious alternative to existing drying methods for stabilizing proteins.

NIR imaging is a useful tool for studying the homogeneity of dried protein-sugar formulations.

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