Preparation and characterization of nimodipine-loaded nanostructured lipid systems for enhanced solubility and bioavailability.

Purpose: Nimodipine (NMP) is a clinical dihydropyridine calcium antagonist. However, the clinical application of NMP is limited by poor water solubility and low oral bioavailability. To overcome these drawbacks, this study designed optimal NMP-incorporated nanostructured lipid carriers (NLCs). Methods: High-pressure homogenization was successfully applied to prepare NMP-NLC, and the nanoparticle morphology was observed by a transmission electron microscope. The existence form of NMP in NMP-NLC was investigated by powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy, respectively. The in vitro release study was performed by the dialysis method, and in vivo studies including in situ intestinal perfusion and pharmacokinetics were investigated in rats with NMP detected by high-performance liquid chromatography. Results: The obtained NMP-NLC shared a spherical shape of similar to 70 nm with a smooth surface and high encapsulation efficiency of 86.8%+/- 2.1%. Spectroscopy indicated that the drug was in an amorphous state. The NMP-NLC exhibited a sustained release and diverse release profiles under different release medium, which mimicked the physiological environment. Moreover, an in situ intestinal perfusion experiment revealed that NMP-NLC could be mainly absorbed by the small intestine. Remarkable improvements in C-max and AUC(0-infinity) from NMP-NLC were obtained from pharmacokinetic experiments, and the relative bioavailability of NMP-loaded nanostructured lipid systems was 160.96% relative to NMP suspensions. Conclusion: Collectively, the NLCs significantly enhanced the oral bioavailability of NMP and might provide a promising nanoplatform for hydrophobic drug delivery.