Drug loading into and drug release from pH- and temperature-responsive cylindrical hydrogels

• Published in: Biotechnology progress Vol. 27; no. 5; pp. 1442 - 1454
• Main Authors: Ninawe, Pravin R., Parulekar, Satish J.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.09.2011; Wiley
• Subjects: Biological and medical sciences; Biotechnology; Diffusion; Drug delivery; Drug Delivery Systems; drug loading; Fundamental and applied biological sciences. Psychology; hydrogel deswelling; hydrogel swelling; Hydrogels; Hydrogen-Ion Concentration; Mathematical models; Models, Theoretical; pH effects; pH-responsive hydrogels; polymer network displacement; Porosity; Pressure; Solvents; Stress; Temperature; Temperature effects; thermally responsive hydrogels; Drug; pH; Temperature; Hydrogel; Release
• ISSN: 8756-7938; 1520-6033; 1520-6033
• DOI: 10.1002/btpr.632

Hydrogels that undergo deformation upon appropriate changes in pH or temperature have considerable promise as drug delivery vehicles. Drug uptake in swelling and nonswelling cylindrical hydrogels and drug release from these into a target fluid are investigated here. A mathematical model for hydrogel‐solution composite, a composite of a distributed parameter system (cylindrical hydrogel) and a lumped parameter system (surrounding solution), is developed. The polymer network displacement in a swelling/deswelling hydrogel is described by a stress diffusion coupling model. The analytical solution for network displacement is used to predict solvent intake by swelling hydrogels, solvent efflux from deswelling hydrogels, and changes in pressure, porosity, and effective drug diffusivity. These in turn influence drug uptake during and after hydrogel swelling and drug release from hydrogel during and after deswelling. Numerical results illustrate benefits of hydrogel swelling for drug loading and merits of different modes of drug release. Drug uptake and drug release by temperature‐responsive hydrogels are compared with those by hydrogels not subject to deformation. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011