15 The internal matrix network between drug and polymer at the core of particles may be stronger than EC100 than EC45 used polymeric nanoparticles. After drying high molecular weight polymer (EC300) may confer stronger film with increased tensile strength and elasticity due to more polymer chain length. Subsequently, high viscosity confer fast solidification of the dispersed phase may contributed to reducing porosity of the particles also.16 Such stronger film may resist hydrostatic pressure and certain less structural damage to the film due to stress fractures. On the other hand, low viscosity grade polymer is more soluble in organic solvent and undergoes

Vandetanib solubility dmso slow solidification to produce more porous particles. It can

also be attributed to the smaller size of particles, which provide more surface area for drug diffusion in dissolution medium. Therefore higher viscosity grade ethylcellulose at given maximum drug-polymer ratio was more sustained than lower viscosity grade ethylcellulose at given minimum drug-polymer ratio. In drug release kinetic determination the correlation coefficients (R2) between the observed release data and fitted profiles are summarized in Table 2. According to correlation coefficients, release data fitted best to the zero order kinetics for EC45, EC100 and EC300 nanoparticles than First order, Higuchi and Korsmeyer models. The zero order rates describe the systems where the drug release rate is independent of time and its concentration mTOR inhibitor within pharmaceutical dosage form. Zero order release kinetic refers to the process of constant drug release over time; minimizing potential peak or trough fluctuations and side effects, while maximizing the time drug concentration remain within the therapeutic window. This constant drug release will help to maintain the drug level in blood throughout the delivery period. To explain the mechanism of drug release ‘n’ values were beyond limits of Korsmeyer–Peppas model, so it called power law which would account for a release Mephenoxalone mechanism of metformin other than Fickian

diffusion. In present release study, particle size distribution or matrix macromolecular network of ethylcellulose or drug loading in matrix could be influenced on release exponent values.17 and 18 This cannot be predicted clearly as it appears to be a complex mechanism of swelling, diffusion and erosion. From all these results it was revealed that different viscosity grade ethylcellulose polymers can encapsulate and sustained highly water soluble metformin HCl efficiently. Oil in oil is the best method to encapsulate maximum amount of highly water soluble drug. Different viscosity grade ethylcellulose polymers affect the particle size, drug content and drug release profile of obtained nanoparticles. Viscosity of internal phase was the main reason behind changing all these characteristics.