L-ASCORBIC-ACID RELEASE FROM PHEMA HYDROGELS

Controlled release of L-ascorbic acid from poly(2-hydroxyethyl methacr ylate) (PHEMA) hydrogels is reported. PHEMA hydrogels were synthesized from 2-hydroxyethyl methacrylate (HEMA) monomer in an oven. We studie d the swelling of PHEMA discs in water as a fuction of temperature and thickness of xerogel discs. The fractional swelling was linear in (ti me)1/2 at short times. Drug release has been examined as a fuction of temperature, initial drug load and thickness of the PHEMA discs. The f raction of avaible drug release was linear in (time)1/2 during the ini tial stage too. The release experiments were carried out at 308 K. The se studies allow to determinate a diffusion coefficient for transport of water into the hydrogels and a diffusion coefficient for L-ascorbic acid release from the hydrogel.