Changchun BCHT Biopharm Co.
Changchun BCHT Biopharm Co.
Sun Y.,Jilin University |
Wang M.,Jilin University |
Wang M.,Changchun BCHT Biopharm Co. |
Sun B.,Jilin University |
And 6 more authors.
Biological and Pharmaceutical Bulletin | Year: 2016
The purpose of this study was to investigate the gastrointestinal stability of exenatide to determine the key factor(s) contributing to peptide degradation during the oral delivery process. The effects of pH and various digestive enzymes on the degradation kinetics of exenatide were determined. Moreover, the degradation clearances of peptide were also examined using rat everted intestinal rings and intestinal homogenates from various intestinal locations. Exenatide was comparatively stable within a pH range of 1.2-8. However, obvious degradation was observed in the presence of digestive enzymes. The order of enzymes, in terms of ability to degradate exenatide, was chymotrypsin>aminopeptidase N>carboxypeptidase A>trypsin>pepsin. Chymotrypsin showed the greatest ability to degrade exenatide (half-life t1/2, 5.784×10-2 h), whereas aminopeptidase N and carboxylpeptidase A gave t1/2 values of 3.53 and 10.16 h, respectively. The degradation of exenatide was found to be peptide concentration- and intestinal site-dependent, with a lower clearance in the upper part of the duodenum and the lower part of the ileum. When using intestinal homogenates as enzyme sources, the order, in terms of peptide degradation ability, was ileum>jejunum>duodenum. However, no significant difference was observed in the remaining peptide concentrations throughout 2 h of incubation, which may be due to the involvement of cytosolic enzymes. These results revealed key factors contributing to peptide degradation, and suggest that the inhibition of chymotrypsin and site-specific delivery of exenatide might be advantageous in overcoming metabolic obstacles during its oral delivery. Copyright © 2016 The Pharmaceutical Society of Japan.
Wang M.-S.,Changchun BCHT Biopharm Co. |
Zheng Y.,Changchun BCHT Biopharm Co. |
Guo L.-S.,Changchun BCHT Biopharm Co. |
Tag L.,Changchun BCHT Biopharm Co. |
And 2 more authors.
Chinese Journal of Biologicals | Year: 2014
Objective To optimize and verify the condition for determination of rabies virus titer by direct immunofluorescence assay (dFA). Methods The influences of inoculation method (stepwise and one-step inoculations) as well as temperature (34 and 37 °C) and time (6, 12, 24, 48, 72 and 96 h) on titer of rallies viius were evaluated bv direct immunofluorescence assay. The optimized method was verified for inter-precision and specificity, and the results were compared with those of intracerebral titration in mice. Results Hie cells were inoculated by one-step inoculation, while vims was cultured at 34 °C for 96 h and stained to evaluate the test result. Fluorescent foci were counted on dav 3 after virus culture to calculate the virus titer. The variation coefficient of 12 test results by two personnel was only 0. 05%. Specific fluorescence was observed onlv in rabies vims but not in canine distemper vims or canine parvovirus by the method. The determination results of virus titers by dFA showed no significant difference with that by intracerebral titration in mice (P> 0. 05 ). Conclusion The optimized dFA is precise, specific, easy to handle and time-saving, which may be used for the quantitative determination of rabies vims liter.