Risperidone Release from Solid Lipid Nanoparticles (SLN): Validated HPLC Method and Modelling Kinetic Profile

A simple reverse-phase (RP) high performance liquid chromatography (HPLC) method was developed and validated, according to the International Harmonisation Guidelines (ICH), for the determination of risperidone (RISP) from solid lipid nanoparticles (SLN). Chromatographic runs were performed on a RP-C18 column, using an isocratic mobile phase of methanol, acetate buffer (0.05 M; pH 4.6) and triethylamine (60: 40: 0.02, v/v/v). The flow rate was 1 ml/min, the run time was 10 min and the RISP absorbance was measured at 280 nm, using UV detection. A linear response was obtained for a RISP concentration range of 0.25 - 10.00 mu g/ml (R-2 = 0.9996), with a detection and quantification limits of 0.011 and 0.034 mu g/ml, respectively. The method was shown to be specific, precise at the intra-day (RSD < 0.796%) and inter-day (RSD < 0.331%) levels, and accurate with recoveries between 86.86 - 100.3% (RSD < 0.613%). Method robustness was observed as well. The suitability of the method for RISP quantifications was assessed by the determination of encapsulation parameters (encapsulation efficiency and drug loading) and by studying the RISP release profile from SLN. Kinetic models (zero order, Higuchi, Korsmeyer-Peppas and Baker-Lonsdale) were used to fit the obtained release profile and to predict the in vivo performance of RISP-loaded SLN. A combined pattern of diffusion and erosion release mechanism (anomalous non-Fickian transport) was found for the RISP-loaded SLN, which shows the ability of the system for controlled drug release.