In vitro drug release study

The dialysis bag method was selected for accomplishing the in vitro drug release study by using PBS 7.4 as the dissolution medium27 and dialysis membrane with a molecular weight of 12,000 Da which retains SLNs and permits the diffusion of free drug into the dissolution medium. The bags were initially soaked in PBS 7.4 for 24 h before being used; then 2 mL of PE-SLNs dispersion was transferred into the bag and the two ends tied by string.27 Subsequently, the bags were placed in 100 mL dissolution medium which was maintained at 37°C and shaken at 100 rpm in a thermostatically controlled shaking water bath (WSB-18, Daihan Scientific Co. Ltd, Gangwon-do, Korea). The first eight samples were withdrawn every hour and then one sample was withdrawn after 24 h and the final sample after 48 h. Samples were withdrawn at predetermined time intervals, replenished with fresh buffer to retain the sink condition and analyzed spectrophotometrically at 265 nm.30