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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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.

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ABSTRACT:In this study, a series of novel pH-sensitive copolymeric butyl acrylate-co-itaconic acid (p(BA-co-IA)) hydrogel microspheres were prepared by modified suspension polymerization of butyl acrylate and itaconic acid with the addition of 5% ethylene glycol dimethacrylate as a cross-linker and 1% benzoyl peroxide as an initiator. Nifedipine, an antihypertensive drug, was successfully encapsulated into these hydrogel microspheres by the equilibrium swelling method. Prepared hydrogel micropsheres were evaluated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffractometry (XRD), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The chemical stability of the nifedipine after being encapsulated into prepared hydrogel microspheres was confirmed by FTIR, DSC, and XRD analysis. TGA indicates that prepared samples showed much better thermal stability than pure drug nifedipine. SEM images showed that prepared p(BA-co-IA) hydrogel microspheres are spherical in shape. The size distribution of prepared samples was found between 4.145 to 10 μm using a Malvern nanosize ZS instrument. The maximum percentage entrapment efficiency of nifedipine was found 67%, and % yield was about 72%. The maximum in vitro release studies of drug-loaded microspheres, which is 94.4% for the pH 7.4 buffer solution, demonstrated the pH sensitivity of prepared hydrogel microspheres. The cumulative drug release data were analyzed by using the Korsmeyer-Peppas equation to calculate a value of diffusion exponent (n), which follows non-Fickian diffusion. C

The development of a new drug entity is a time-consuming and an expensive process; therefore, the design of new drug delivery systems for an existing drug molecule can significantly improve the safety and efficacy of the drug with improved patient compliance. In recent years, polymeric carriers have been widely investigated and are playing an important role in controlled drug delivery, biomedical applications, and tissue engineering. Microgels are microscopic hydrogels and have attracted much attention as vehicle for drug delivery. Stimuli-responsive MGs are smart drug delivery carriers and have the capability to incorporate and release their host molecules in response to stimuli (pH, ionic strength, and temperature), for targeted drug delivery. Of the many stimuli, alteration in pH is markedly fascinating because of the availability of pH gradients admissible for drug targeting. For example, pH gradients between normal tissues and some pathological sites between the extracellular environment and some cellular compartments, and along the gastrointestinal (GI) tract, are well characterized. Microgels can be fabricated through different methods.

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