In vitro characterization and in vivo evaluation of nanostructured lipid curcumin carriers for intragastric administration

Background: Curcumin has a variety of pharmacological effects. However, poor water solubility and low oral bioavailability limit its clinical utility. A delivery system for nanostructured lipid carriers has been reported to be a promising approach to enhancing the oral absorption of curcumin. The aim of the present study was to investigate the pharmacokinetics, tissue distribution, and relative bioavailability of curcumin in rats after a single intragastric dose of a nanostructured lipid curcumin carrier formulation. Methods: Nanostructured lipid curcumin carriers were prepared using the ethanol dripping method and characterized in terms of the particle size, polydispersity index, zeta potential, differential scanning calorimetry, drug-loading capacity, encapsulation efficiency, and in vitro release. The pharmacokinetics and tissue distribution of nanostructured lipid curcumin carriers and curcumin suspension were compared after intragastric administration. Results: Nanostructured lipid curcumin carriers showed a significantly higher peak plasma concentration (564.94 +/- 14.98 ng/mL versus 279.43 +/- 7.21 ng/mL, P<0.01), a shorter time taken to reach peak plasma concentration (0.5 +/- 0.01 hour versus 1.0 +/- 0.12 hour, P. 0.01), and a greater AUC(0-infinity) (820.36 +/- 25.11 mg x hour/L versus 344.11 +/- 10.01 mg x hour/L, P < 0.05) compared with curcumin suspension. In the tissue distribution studies, curcumin could be detected in the spleen, heart, liver, kidneys, lungs, and brain. Following intragastric administration of the nanostructured lipid curcumin carrier formulation, tissue concentrations of curcumin also increased, especially in the brain. The nanostructured lipid curcumin carrier formulation improved the ability of curcumin to cross the blood-brain barrier, with an 11.93-fold increase in the area under the curve achieved in the brain when compared with curcumin suspension. Conclusion: The nanostructured lipid carrier formulation significantly improved the oral bioavailability of curcumin and represents a promising method for its oral delivery.