Photopolymerization of multilaminated poly(HEMA) hydrogels for controlled release

A novel approach to immobilize nonuniform initial drug concentration profiles in multilaminated matrix devices utilizing photopolymerization techniques is presented. Solution polymerization of 2-hydroxyethyl methacrylate (HEMA) and diethylene glycol dimethacrylate (DEGDMA) in the presence of a model compound, acid orange 8 (AO8), was conducted using UV light and photoinitiators to construct a laminated matrix device. In this process, each layer was polymerized with a different AO8 concentration to form a nonuniform initial concentration profile in the matrix devices. The AO8 diffusion coefficients measured in this work were used in a concurrently developed model to predict the effects of nonuniform AO8 concentration profiles on AO8 release patterns. The release data predicted by the model agreed well with the experimentally determined data. The results indicate that a zero-order release pattern can be approximated by employing a suitable nonuniform initial drug concentration profile.