Drug-Eluting Polyacrylate Microgels: Loading and Release of Amitriptyline

Area of Science:

• Materials Science
• Chemical Engineering
• Pharmaceutical Sciences

Background:

• Amphiphilic drugs require specialized delivery systems for controlled release.
• Hydrogel swelling and drug self-assembly significantly impact drug loading and release kinetics.

Purpose of the Study:

• To investigate the loading and release mechanisms of amitriptyline hydrochloride (AMT) in sodium polyacrylate hydrogels.
• To elucidate the influence of drug self-assembly and hydrogel network swelling on controlled-release kinetics.
• To inform the development of improved parenteral controlled-release systems for amphiphilic drugs.

Main Methods:

• Equilibrium studies using micro- and macrogels to observe swelling transitions.
• Time-resolved micropipette-assisted microscopy to visualize drug loading and release dynamics.
• Kinetic modeling incorporating drug self-assembly, phase separation, and volume changes.

Main Results:

• Observed discrete and gradual swelling transitions in microgels and macrogels, respectively, at critical drug concentrations.
• Drug self-assemblies formed dense shells during loading and dense cores during release.
• Mass transport in different gel phases and surrounding liquid influenced loading and release rates.

Conclusions:

• Drug self-assembly and hydrogel network dynamics dictate AMT loading and release mechanisms.
• A developed kinetic model accurately describes the observed loading and release processes.
• Findings are crucial for designing effective controlled-release hydrogel systems for parenteral drug delivery.