Preparation, optimization by 23 factorial design, characterization and in vitro release kinetics of lorazepam loaded PLGA nanoparticles
The aim of this work was to formulate the lorazepam loaded poly(lactic co glycolic) acid (PLGA) nanoparticles by optimization of different preparation variables using 23 factorial design. The effect of three independent factors, the amount of polymer, concentration of the stabilizer and volume of organic solvent was investigated on two dependent responses, i.e. particle size and drug entrapment efficiency. By using PLGA as polymer, PVA as a stabilizer and dimethyl sulfoxide as organic solvent lorazepam loaded PLGA nanoparticles were successfully developed through modified nanoprecipitation method. FTIR and DSC studies were carried out to examine the interaction between the excipients used and to explore the nature of the drug, the formulation and the nature of drug in the formulations. These nanoparticles were characterized for particle size, shape, zeta potential, drug entrapment efficiency, process yield and in vitro drug release behavior. In vitro evaluation showed particles size between 161.0 5.4 and 231.9 4.9 nm, drug entrapment efficiency of formulations was in the range of 60.43 5.8 to 75.40 1.5, process yield at 68.34 2.3 to 81.55 1.3 was achieved and in vitro drug release for these formulations was in the range of 49.2 to 54.6% Different kinetics models, such as zero order, first order, Higuchi model, Hixson Crowell model and Korsmeyer Peppas model were used to analyze the in vitro drug release data. Preferred formulation showed particle size of 161.0 5.4 nm, PDI as 0.367 0.014, 25.2 mV zeta potential, drug entrapment efficiency as 64.58 3.6% and 72.48 2.5% process yield. TEM results showed that these nanoparticles were spherical in shape, and follow the Korsmeyer Peppas model with a release exponent value of n 0.658.