Development of SLN and NLC enriched hydrogels for transdermal delivery of nitrendipine: in vitro and in vivo characteristics.

The purpose of this research was to investigate novel particulate carrier systems such as solid lipid nanoparticles (SLN) and nanostructured lipid carrier (NLC) for transdermal delivery of nitrendipine (NDP). For this investigation, four different gel-forming agents were selected for hydrogel preparation. Aqueous dispersions of lipid nanoparticles made from trimyristin (TM) were prepared by hot homogenization technique followed by sonication and then incorporated into the freshly prepared hydrogels. The particle size was analyzed by photon correlation spectroscopy (PCS) using Malvern zetasizer, which shows that for all the tested formulations, more than 50% of the particles were below 250 nm after 90 days of storage at room temperature. DSC analysis was performed to characterize the state of drug and lipid modification. Shape and surface morphology were determined by scanning electron microscope (SEM) and transmission electron microscope (TEM), which revealed fairly spherical shape of the formulations. The antihypertensive activity of the gels in comparison with that of oral NDP was studied using desoxy corticosterone acetate (DOCA)-induced hypertensive rats. It was observed that both carbopol SLN (A1) and carbopol NLC (B1) gels significantly controlled hypertension from the first hour (p < .05). The developed gels increased the efficacy of NDP for the therapy of hypertension. Both the SLN and NLC dispersions and the gels enriched with SLN and NLC possessed a sustained drug release over a period of 24 h, but the sustained effect was more pronounced with the SLN and the NLC gel formulations. Further, they were evaluated for zeta potential, entrapment efficiency, in vitro release, ex vivo permeation, and skin irritation studies.