Abstract

Lysozyme, a model protein, was used to study the effects of excipients (lactitol, copovidone and gelucire 44/14) on the protein biological activity. Three different concentrations (0.1, 0.5 and 10 %w/v) of the excipients were used with a relatively high (10%w/v) lysozyme concentration. Analytical methods such as UV spectroscopy and fluorescence technique were used to study the effect of excipients on protein biological stability and integrity. The data obtained from analysis showed that gelucire 44/14 had a disadvantage effect on lysozyme stability as a single excipient. However, by combining gelucire 44/14 with lactitol, the protein activity was preserved. Also, the combination of lactitol and copovidone preserved the integrity and activity of 6% lysozyme to a great extent. Different excipients stabilised proteins to different degree. As conclusion, there is no excipient that works well for even one type of proteins. The most suitable excipient for each particular protein is found by extensive research studying the activity and stability of the protein in the presence of excipients. High efficacy and accuracy analytic methods should be used in order to give reliable information on protein stability and integrity.

Keywords: lysozyme, lactitol, copovidone, gelucire 44/14, stability, biological activity.