Kinetics of a drug release from a delayed release device

Reaction of sodium salt of benzoic acid with methacryloyl chloride provides an anhydride which is polymerized by the radical method or copolymerized with various percentages of ethylene glycol dimethacrylate to obtain crosslinked products. Hydrolysis reactions of the resulting polymers were carried out in various aqueous solutions and the rate of release of benzoic acid (simulator of drug) seems to depend both on the percentages of crosslinking comonomer and on the pH of the solution. A model of this delayed release of benzoic acid is also proposed.