A polymeric controlled drug delivery device for peptides based on a surface desorption/diffusion mechanism

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Polymer Chemistry

Background:

• Continuous peptide delivery is crucial for effective therapeutic applications.
• Existing drug delivery systems face challenges in achieving long-term, stable release profiles.
• Understanding peptide-polymer interactions is key to designing advanced delivery modules.

Purpose of the Study:

• To investigate the mechanisms of continuous peptide delivery from a novel Accurel polypropylene/collodion device.
• To evaluate the pseudo-zero-order release kinetics of vasopressin (VP) from the developed module.
• To explore the role of peptide adsorption and desorption on polypropylene surfaces in controlling release.

Main Methods:

• Fabrication of a peptide delivery module by lumen-loading microporous Accurel polypropylene tubing with an aqueous peptide solution, followed by end-sealing and encapsulation with a collodion membrane.
• Utilizing vasopressin (VP) as a model peptide to study its adsorption and desorption characteristics on the polypropylene surface.
• Assessing peptide release kinetics under 'infinite sink' conditions over extended periods.

Main Results:

• Vasopressin exhibited prominent adsorption onto the polypropylene surface, characterized by a bimodal isotherm with limited desorption.
• The peptide-device interaction showed characteristics of semi-reversible protein/polymer surface interactions.
• The collodion membrane thickness ( > 60 microns) effectively prevented external protein exchange, ensuring sustained release.
• Linear cumulative release curves for vasopressin were observed for weeks under 'infinite sink' conditions, supporting a pseudo-zero-order release mechanism.

Conclusions:

• The developed Accurel polypropylene/collodion device enables sustained, pseudo-zero-order peptide delivery.
• Peptide adsorption to the polypropylene surface acts as a reservoir, controlling the release rate.
• This novel system, loaded with an unsaturated solution and not solely reliant on the encapsulating membrane for rate control, represents an advancement in reservoir-based drug delivery systems.