Novel solid lipid nanoparticles as carriers for oral administration of insulin.

The aim of this study was to propose novel solid lipid nanoparticles (SLNs) loaded with cell-penetrating peptide (CPP), and to evaluate their potential for oral administration of insulin. Octaarginine (R8) was used as the CPP. SLNs loaded with insulin and R8 (Ra-Ins-SLNs) were prepared using the spontaneous emulsion solvent diffusion method. The morphological study of R8-Ins-SLNs showed its spherical shape using transmission electron microscopy (TEM) photography. The mean particle size, zeta potential, encapsulation efficiency (EE %) of insulin and R8 were 150.8 +/- 23.4 nm, 32.65 +/- 2.02 mV, 62.29 +/- 0.52% and 58.05 +/- 0.66%, respectively. The in vitro release of insulin or R8 from R8-Ins-SLNs was characterized by an initial rapid release and subsequent sustained release in pH 6.8 dissolution media. In vivo absorption experiments provided a relative pharmacological bioavailability (PA%) value of R8-Ins-SLN of 10.39 +/- 0.46%. These results suggest that SLNs loaded with CPP could be a promising perioral carrier for insulin.