Drug release from ion-exchange microspheres: mathematical modeling and experimental verification

Area of Science:

• Biomaterials Science
• Chemical Engineering
• Pharmaceutical Sciences

Background:

• Controlled drug delivery systems are crucial for therapeutic efficacy.
• Ion-exchange mechanisms offer a promising approach for drug release modulation.
• Understanding the interplay between ion exchange and diffusion is key to designing effective systems.

Purpose of the Study:

• To develop and validate a novel mathematical model for controlled drug release.
• To investigate the influence of various parameters on drug release kinetics.
• To provide a predictive tool for optimizing ion-exchange drug delivery systems.

Main Methods:

• Development of a mathematical model incorporating ion exchange and counter-diffusion.
• Numerical analysis of drug and counterion concentration profiles.
• Validation using a verapamil hydrochloride and sulfopropyl dextran microsphere system.

Main Results:

• Model predicts distinct regions within microspheres: unextracted, ion-exchange, and diffusion.
• Drug release rate is influenced by initial drug concentration, external salt concentration, and counterion valence.
• Release rate decreases with increasing Langmuir isotherm constant.

Conclusions:

• The developed mathematical model accurately predicts drug release kinetics and equilibrium.
• The model serves as a valuable tool for designing and optimizing ion-exchange drug delivery systems.
• This work advances the understanding of complex drug release mechanisms in microspheres.