Effect of vacuum drying on protein-mannitol interactions: The physical state of mannitol and protein structure in the dried state |
| |
Authors: | Vikas K Sharma Devendra S Kalonia |
| |
Institution: | (1) Department of Pharmaceutics, University of Minnesota, 308 Harvard Street SE, Minneapolis, Minnesota 55455, USA;(2) Human Genome Science, Inc., 9410 Key West Avenue, Rockville, Maryland 20850, USA; |
| |
Abstract: | The purpose of the present studies was to systematically investigate protein-mannitol interactions using vacuum drying, to
obtain a better understanding of the effect of protein/mannitol wt/wt ratios on the physical state of mannitol and protein
secondary structure in the dried state. Solutions containing β-lactoglobulin (βLg):mannitol (1∶1–1∶15 wt/wt) were vacuum dried
at 5°C under 3000 mTorr of pressure. The physical state of mannitol was studied using x-ray powder physical state of mannitol
was studied using x-ray powder diffractometry (XRPD), polarized light microscopy (PLM), Fourier-transform infrared (FTIR)
spectroscopy, and modulated differential scanning calorimetry (MDSC). XRPD studies indicated that mannitol remained amorphous
up to 1∶5 wt/wt βLg:mannitol ratio, whereas PLM showed the presence of crystals of mannitol in all dried samples except for
the 1∶1 wt/wt βLg:mannitol dried sample. FITR studies indicated that a small proportion of crystalline mannitol was present
along with the amorphous mannitol in dried samples at lower (less than 1∶5 wt/wt) βLg:mannitol ratios. The Tg of the dried 1∶1 wt/wt βLg:mannitol sample was observed at 33.4°C in MDSC studies, which indicated that at least a part of
mannitol co-existed with protein in a single amorphous phase. Evaluation of the crystallization exotherms indicated that irrespective
of the βLg:protein wt/wt ratio in the initial sample, the protein to amorphous mannitol ratio was below 1∶1 wt/wt in all dried
samples. Second-derivative FTTR studies on dried βLg and recombinant human interferon α-2a samples showed that mannitol affected
protein secondary structure to a varying degree depending on the overall mannitol content in the dried sample and the type
of protein. |
| |
Keywords: | |
本文献已被 PubMed SpringerLink 等数据库收录! |
|