Curcumin, extracted from the rhizomes of turmeric, has been reported to possess anti-oxidative,
anti-inflammatory and anti-carcinogenic activities. Tetrahydrocurcumin (THC) is one
of curcumin metabolites. THC exhibits similar pharmacological activities as curcumin;
nevertheless, it shows the more potent antioxidant than curcumin [1, 2]. However,
the pharmacological effect of THC is limited due to its low aqueous solubility. Self-microemulsifying
drug delivery systems (SMEDDS) have been used for the improvement of oral bioavailability
of insoluble lipophilic compounds. SMEDDS are isotropic mixtures of oils and surfactants
that form fine oil-in-water microemulsions upon mild agitation in aqueous media such
as GI fluids [3]. The optimized SMEDDS used for THC formulations in liquid form contained
70% mixtures of two surfactants: Cremophor EL and Labrasol (1:1), and 30% mixtures
of oil: Labrafac PG and Capryol 90 (1:1). The liquid THC-SMEDDS rapidly formed fine
oil-in water-microemulsions, with particle size of less than 50nm. The in vitro rate
and extend of release of THC from liquid-SMEDDS was about 16- fold higher than that
of unformulated THC. Our studies demonstrated the potential use of self-microemulsifying
drug delivery system for the delivery of hydrophobic compounds, such as THC by the
oral route.
Acknowledgements: Financial support from Thailand Research Fund under the Royal Golden Jubilee Ph.D.
programme (PHD/0150/2549) and the Royal Thai Government through Prince of Songkla
University.
References: 1. Anand, P. et al. (2008) Molec. Pharm. 4:807–818.
2. Yoysungnoen, P. et al. (2008) World J. Gastroenterol. 14:2003–2009.
3. Constantinides P.P. (1997) Int. J. Pharm. 158:57–68.
