Therapeutic use of curcumin is strongly limited by low oral bioavailability [1]. Our
work was focused on the development and characterization of different lipid nanovectors,
namely solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and microemulsions
containing curcumin. A comparison of their in vitro performance was carried out by
Parallel Artificial Membrane Permeability Assay (PAMPA), a validated artificial method
easy to use for predicting in vivo gastro-enteric permeability. The vectors were fully
characterized, and stability and in vitro drug release were also investigated. The optimized Compritol® 888 ATO SLN formulation
showed a mean particle size lower than 300nm, a zeta potential of -33 mV and 80% drug
entrapment efficiency. It was stable over one month. The presence of round shape SLN
with homogeneous size distribution was confirmed by TEM analysis. NLCs formulations
contain 80% Compritol, 20% vitamin E or 95% glyceryl monostearate, 5% vitamin E. Both
contain Poloxamer 188 and 20 mg of curcumin. Sizes were below 300nm and drug entrapment
efficiency was about 60%. In both NLCs and SLNs, an immediate release of the curcumin
within 30 minutes was evidenced, followed by a plateau phase for ca. 5 – 6 hours.
PAMPA systems showed a considerable increasing of the amount of curcumin permeated
in both SLNs and NLCs compared to curcumin suspension. Three microemulsions were developed
using Cremophor EL, Tween 20, Tween 80 or Lecitin, olive oil, wheat germ oil, vitamin
E. The optimized microemulsion contains vitamin E (3.3%), Tween® 20 (53.8%), ethanol
(6.6%) and water (36.3%). It resulted the best in terms of size, polidispersity, encapsulation
efficiency and positive influence on the solubility of curcumin (14.57 mg/ml). The
microemulsion is stable for two months and showed a permeation % through the artificial
membrane of about 70%. SLNs, NLCs and microemulsions offer a promising delivery systems
for improving oral bioavailability of curcumin.
Keywords: Curcumin, lipid nanovectors, solid lipid nanocapsules, nanostructured lipid carriers,
microemulsions, gastro-enteric permeability
References:
[1] Anand, P. et al. Mol Pharmacology 2007; 4: 807 – 818.
