Soybean Oil in Nifedipine-Loaded Nanostructured Lipid Carriers: Enhancing Drug Loading and Release

Nanostructured lipid carriers (NLCs) are widely recognized for their ability to improve drug loading (DL) capacity and release characteristics for poorly water-soluble drugs. In this study, nifedipine-loaded NLCs (NLC-NIs) were prepared using an ultrasonic emulsification method. The effects of dispersion energy and sonication time on the optimization of the preparation process were systematically investigated. The influence of soybean oil (SO) content, ranging from 5% to 25% w/w of the total lipid, on the physicochemical properties, entrapment efficiency (EE), and drug loading capacity (DL) was evaluated and compared with nifedipine-loaded solid lipid nanoparticles (SLN-NI). Results indicated that both %EE and %DL increased with higher SO concentrations. At the highest SO content, EE and DL were achieved at 97.66% ± 0.06 and 19.52% ± 0.01, respectively, while SLN-NI exhibited significantly different (p < 0.05) lower EE and DL values of 41.63% ± 0.10 and 8.32% ± 0.01, respectively. The particle size of NLC-NI 5 was 281.9 ± 16.4 nm, which was slightly larger with significantly different (p < 0.05) than that of SLN-NI (220.3 ± 14.5 nm). Additionally, NLC-NI demonstrated a superior sustained release profile in vitro compared to SLN-NI. In conclusion, the incorporation of SO in NLC formulations markedly improved drug EE, DL, and sustained release characteristics compared to solid lipid nanoparticles.