EFFECT OF LOADING METHOD ON NSAIDS RELEASE FROM ETHYLENE-GLYCOL DIMETHACRYLATE CROSS-LINKED POLY(2-HYDROXYETHYL METHACRYLATE) MICROSPHERES

Different loading methods: soaking in aqueous solutions or drug incorp oration in the reaction mixture were analyzed in poly(HEMA) EGDMA cros s-linked microspheres for a series of NSAIDs. The influence of the loa ding method on both loading levels and release kinetics was studied. I ncorporation in the reaction mixture gave higher loading levels than s oaking. The release rate was higher in the presence of drug incroporat ion in the reaction mixture due to a higher dispersion of the drug in the polymer promoting a higher dissolution rate. Release kinetics appr oaches zero order both during and after the microsphere swelling perio ds.