This work investigates Ethyl cellulose (EC) and polyethylene glycol (PEG) microparticles for prolonged delivery of Metformin HCl.The microparticles were synthesised by emulsion solvent evaporation technique; characterized for encapsulation efficiency, particle size, flow properties, surface morphology, FTIR, PXRD and drug release pattern; and investigated for the effect of formulation parameters like EC:PEG ratio, drug to polymers ratio and stirring speed on various properties of the microparticles. The drug entrapment efficiency, percent yield, particle size and drug release behaviour were found to be influenced by various formulation parameters.SEM images and size analysis confirmed formation of spherical shaped microparticles, with slightly rough surface and good flowability. FTIR revealed absence of any drug-polymer interaction and PXRD confirmed the molecular dispersion of drug with in microparticles. All the formulations showed sustained drug release pattern at pH 6.8, up to 91.34% ±1.68 metformin was released in 12 h with fickian diffusion mechanism. The designed microparticles could possibly be advantageous in terms of prolonged release, to achieve reduced dose frequency and improved patient compliance.

The present work focused on the synthesis and evaluation of cross-linked poly (2-methoxyethyl methacrylate-co-itaconic acid) [p(MEMA-co-IA)] microgels for controlled and extended drug delivery, in an attempt to improve the bioavailability of the drugs and to get maximum therapeutic benefits. A series of p(MEMA-co-IA) microgels were prepared by modified free-radical suspension polymerization using ethylene glycol dimethacrylate as cross-linker. Characterization was performed through FTIR, TGA, DSC, XRD, DLS and SEM. pH responsiveness was evaluated by equilibrium swelling studies in phosphate buffer solutions of different pH values (pH 1.2, 4, 6.5, and 7.4) with constant ionic strength. To demonstrate the potential use of microgels for drug delivery, esomeprazole magnesium trihydrate (EMT) was loaded as model drug and in vitro dissolution studies were performed. FTIR and thermal analysis confirmed the formation of cross-linked p(MEMA-co-IA) microgels. XRD indicated dispersion of drug into the network at molecular level. SEM illustrated smooth, round and uniformly distributed microspheres. A remarkably higher swelling at higher pH values (pH 6.5 and 7.4) compared to pH 1.2 demonstrated the pH-responsive nature of the microgels. All the formulations showed pH-dependent drug release following Higuchi with non-fickian mechanism of drug diffusion. In light of the results obtained from this study, it was concluded that p(MEMA-co-IA) microgels have potential to release drug in controlled manner responsive to pH of the external environment.

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