Comparative Study of Stavudine Microspheres Prepared Using Ethylcellulose Alone and in Combination with Eudragit® Rs100

Stavudine microspheres were prepared using ethylcellulose alone and in combination with EudragitRS100 by emulsion solvent diffusion method to sustain the release of drug from microspheres. The effect of drug-polymer ratio and stirring speed on percentage yield, encapsulation efficiency, particle size, in vitro release profiles and kinetics of drug release of microspheres were evaluated. The size distribution of the prepared microspheres was done by microscopic method and in vitro dissolution studies were carried out in phosphate buffer (pH 6.8) as the dissolution media to study the drug release profile of the microspheres. Surface topography of microspheres was characterised using scanning electron microscopy (SEM). Fourier transformer infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were performed to evaluate interaction between drug and polymer(s) which revealed to be compatible. The encapsulation efficiency was found satisfactory and it decreased significantly (p 0.05) with increase in drug-polymer concentration. Both the drug-polymer ratio and stirring speed affects the physicochemical properties and release of drug from microspheres. The prepared microspheres satisfactorily released the drug in a sustained and uniform rate following Higuchian kinetics. Sustained release microsphere of stavudine has a potential for oral administration at least once every 12 h