Stabilisation and determination of the biological activity of L-asparaginase in poly(DL-lactide-co-glycolide) nanospheres

Stabilisation and determination of the biological activity of L-asparaginase in poly(DL-lactide-co-glycolide) nanospheres
April 2003
M. Wolf, M. Wirth, F. Pittner and F. Gabor
International Journal of Pharmaceutics, Volume 256, Issues 1-2, 30 April 2003, Pages 141-152
Science Direct
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The preservation of biological activity of protein drugs in formulations is still a major challenge for successful drug delivery. The enzyme Image-asparaginase, which exhibits a short in vivo half-life and is only active against leukaemia in its tetrameric form, was encapsulated in poly(Image,Image-lactide-co-glycolide) nanospheres by the (w/o)/w-emulsion solvent evaporation technique in presence of various potential stabilisers. Elucidation of the preparation steps revealed that the enzyme is denaturated at the aqueous/organic interface and by sonication. The preparation of Image-asparaginase nanospheres with trehalose, PEG 400, and glycerol as components of the inner aqueous phase yielded colloidal formulations with increased biological activity as determined by an improved protocol for quantification of the active enzyme encapsulated. After lyophilisation the enzyme activity and particle size distribution were retained only by use of Pluronic F68 as a lyoprotectant. Despite the unaltered particle size and improved biological activity, the release profile of the enzyme was strongly altered by coencapsulation of the stabilisers resulting in increased first bursts. In consequence, the biological activity of Image-asparaginase during preparation and storage can be improved by combining appropriate additives but concurrently the release profile is influenced.