Abstract: Poly (methacrylic acid co-poloxamer) hydrogel networks were synthesized by free-radical solution polyme-rization, and the dynamic swelling and in vitro release properties of model drugs, dextromethorphan hydrobromide (DMP) and vitamin B12 (VB12) were studied. These gels exhibited pH-dependant swelling and sustained drug release properties, and the water uptake rate and drug release rate in neutral or basic media were higher than that in acidic media. The results showed that the water uptake followed non-Fickian or zero order process in neutral or basic media, and the release of model drugs from hydrogels of appropriate composition was of zero order kinetics over a period of several hours.

Key words: methacrylic acid, methacrylic acid, poloxamer, poloxamer, pH dependent hydrogel, pH dependent hydrogel, swelling, swelling, drug release, drug release