2.7. In Vitro Release Studies

The dialysis bag diffusion technique and a USP paddle diffusion apparatus were applied to the study of the in vitro release profile of the drug from PPZ-SLNs [33]. The appropriate amount of lyophilized nanoparticles equivalent to 500 μg of PPZ was dispersed in previously prepared simulated intestinal fluid (pH = 6.8) as the release medium and was transferred to a dialysis bag with a molecular cutoff of 12400 Da. The dialysis bag was immersed in 250 ml of the preheated release medium and stirred at 50 rpm. Throughout the experiment, the temperature was kept constant at 37 ± 1°C using a temperature-controlled water bath. Samples (3 ml) were taken at predetermined time intervals of up to 48 hours, and the amount of PPZ released from nanoparticles was determined using HPLC. PPZ dispersed in purified water was used as the control.