Consequences of Formulation Variables on Physicochemical Properties of Indinavir Sulfate Microspheres

Indinavir sulfate with ethyl cellulose microspheres was successfully prepared by an oil-in-oil emulsion solventevaporation technique using acetonitrile: dichloromethane (1:1) and light liquid paraffin as primary andsecondary oil phases respectively with span 80 as a droplet stabilizer. In present study the effect of formulationvariable e.g., polymer to drug ratio, viscosity of ethyl cellulose, volume of light liquid paraffin and effect ofprocessing temperature on yield, encapsulation efficiency, particle size and in vitro drug release characteristicsof the Indinavir microspheres were investigated. The prepared microspheres were spherical with stable nature ofdrug within the formulations confirmed by Fourier transform infrared spectra. The mean sphere diameter andencapsulation efficiencies depended strongly on the drug to polymer ratio, viscosity of polymer, volume ofprocessing medium and processing temperature. The release of indinavir sulfate was diffusion controlled andinfluenced by the drug to polymer ratio, viscosity of polymeric phase, volume of light liquid paraffin used andprocessing temperature condition