Related Experiment Video
Updated: May 30, 2026

PLGA Nanoparticles Formed by Single- or Double-emulsion with Vitamin E-TPGS
Published on: December 27, 2013
Extending residence time and stability of peptides by protected graft copolymer (PGC) excipient: GLP-1 example
Gerardo M Castillo1, Sandra Reichstetter, Elijah M Bolotin
1PharmaIN Corporation, 720 Broadway Suite 511, Seattle, Washington 98122, USA. gcastillo@pharmain.com
Purpose:
To determine whether a Protected Graft Copolymer (PGC) containing fatty acid can be used as a stabilizing excipient for GLP-1 and whether PGC/GLP-1 given once a week can be an effective treatment for diabetes.
Methods:
To create a PGC excipient, polylysine was grafted with methoxypolyethyleneglycol and fatty acid at the epsilon amino groups. We performed evaluation of the binding of excipient to GLP-1, the DPP IV sensitivity of GLP-1 formulated with PGC as the excipient, the in vitro bio-activity of excipient-formulated GLP-1, the in vivo pharmacokinetics of excipient-formulated GLP-1, and the efficacy of the excipient-formulated GLP-1 in diabetic rats.
Results:
We showed reproducible synthesis of PGC excipient, high affinity binding of PGC to GLP-1, slowed protease degradation of excipient-formulated GLP-1, and that excipient-formulated GLP-1 induced calcium influx in INS cells. Excipient-formulated GLP-1 stays in the blood for at least 4 days. When excipient-formulated GLP-1 was given subcutaneously once a week to diabetic ZDF rats, a significant reduction of HbA1c compared to control was observed. The reduction is similar to diabetic ZDF rats given exendin twice a day.
Conclusions:
PGC can be an ideal in vivo stabilizing excipient for biologically labile peptides.
More Related Videos
11:27A Package of Established Analytical Tools to Investigate the Solid-State Alteration of Lipid-Based Excipients
Published on: August 9, 2022
15:33Microwave-assisted Functionalization of Poly(ethylene glycol) and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation
Published on: October 29, 2013
Related Concept Videos
Bioavailability Enhancement: Drug Stability Enhancement and GI Retention
Site-Targeted Drug Delivery Systems: Polymeric Carriers
Oral Drug Delivery Systems: Delayed-Release Systems
Modified-Release Drug Delivery Systems: Rate-Programmed II
Glucagon-like Receptor Agonists
GLP-1, when administered in high doses intravenously, triggers insulin secretion, inhibits glucagon release, slows gastric emptying, reduces food intake, and restores normal insulin secretion. However, its rapid inactivation by the...
Oral Drug Delivery Systems: Continuous-Release Systems