Swelling and dissolution kinetics during peptide release from erodible anionic gel beads

Area of Science:

• Polymer Science
• Materials Science
• Drug Delivery

Background:

• Investigating drug release from erodible polymers is crucial for controlled delivery systems.
• Poly(methyl methacrylate-co-methacrylic acid) (PMMA/MAA) beads are used for peptide delivery.
• Understanding swelling and dissolution dynamics is key to optimizing release profiles.

Purpose of the Study:

• To investigate the transient dynamic swelling and dissolution behavior of erodible PMMA/MAA beads during peptide release.
• To examine the effect of buffer concentration on these processes at pH 7.4.
• To document the synchronization of swelling and dissolution fronts in spherical erodible samples.

Main Methods:

• Dynamic swelling and dissolution behavior of [D-Trp2-D-Phe5]GHRP-loaded PMMA/MAA beads were studied.
• Experiments were conducted at pH 7.4 across varying buffer concentrations.
• Polymer bead diameter changes and peptide release were monitored over time.

Main Results:

• Swelling front penetration followed ionization-limited behavior.
• Bead diameter showed an initial rise then a linear decline due to dissolution.
• Synchronization of swelling and dissolution fronts was observed, influenced by buffer concentration.
• Lower buffer concentrations resulted in slower peptide release and longer release durations.

Conclusions:

• Synchronization of swelling and dissolution fronts in spherical erodible polymers was documented for the first time.
• Buffer concentration significantly affects the synchronization and peptide release kinetics.
• While synchronization occurs, spherical geometry prevents a constant release rate, leading to non-Fickian release characteristics.