Effects of solution pH on ion distribution and drug release behaviors of a weak polyelectrolyte hydrogel

Abstract

A triphasic model is developed and the finite element method is adopted to investigate a weak polyelectrolyte hydrogel. The influence of HCl concentrations in external solution on ion concentrations inside the hydrogel and the evolution of water volume fraction are discussed. The conservation of charge can be satisfied everywhere in the hydrogel. Also, a drug release equation which considers both convection and diffusion effects is employed to analyze the drug release rate. The results show that the drug release rate has a very close relationship with the pH value. The simulated results are compared with experimental results of Beebe to validate the reliability and accuracy of this simulation. This work is significant for the study of oral drug controlled release in the gastrointestinal tract. © 2017 Society of Chemical Industry