Mannitol, enzyme stabilization

Lyoprotectants can affect enzyme stability in both stages of lyophilization the freezing and the drying stages. In the freezing stage of lyophilization, ice crystals form and have been shown to be a cause of enzyme denaturation. Studies have shown that when added as a lyoprotectant, the amorphous polyol mannitol stabi-... 

K. Izutsu, S. Yoshioka, and T. Terao, Effect of mannitol crystallinity on the stabilization of enzymes during freeze drying, Chem. Pharm. Bull. (Tokyo), 42, 5 (1994). 

Summarizing the results of many investigations, monosaccharides and such derivatives as D-mannitol and D-glucitol are rather weak acceptors. Disaccharides, including such acceptor products as isomaltose, are much better acceptors, except for certain molecules, for instance leucrose, which is not an acceptor.29,46,47 The decrease of enzyme activity with time has been described in terms of a first-order reaction. The inactivation parameters have been calculated for the immobilized enzyme. The inactivation constants kd were 0.0135 (1/d) when maltose was the acceptor (stabilizing), and 0.029 (1/d) when fructose was the acceptor.38... 

Protein drugs have been formulated with excipients intended to stabilize the protein in the milieu of the pharmaceutical product. It has long been known that a variety of low molecular weight compounds have the effect of preserving the activity of proteins and enzymes in solution. These include simple salts, buffer salts and polyhydroxylated compounds such as glycerol, mannitol, sucrose and polyethylene glycols. Certain biocompatible polymers have also been applied for this purpose such as polysaccharides and synthetic polymers such as polyvinyl pyrrolidone and even nonionic surfactants. 

Many proteins and peptides are susceptible to degradation upon spray drying due to relatively high temperatures. In a recent study, the effects of inlet and outlet temperatures on some spray-dried peptides and proteins were reported (46). In another study, enzyme activity was found to be susceptible to spray-drying temperature and only half of its activity remained after spray drying without additives at outlet temperatures <50°C (47). In this study, it was found that the activity of a formulation consisting of enzyme and mannitol was maintained at outlet temperatures <50°C and compromised at temperatures >50°C. Replacing mannitol with trehalose stabilized the spray-dried enzyme and its activity was maintained at 100% at an outlet temperature of 100°C. 

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