Taxifolin, allocated from wood of larch, has a wide spectrum of biological activity,
showing antioxidative, capillaroprotective, anti-inflammatory and antithrombotic effects
[1,2]. Taxifolin is a poorly water soluble compound and has low bioavailability. There
is an actual development of new drug forms on the basis of taxifolin. Self-microemulsifying
drug delivery systems (SMEDDS) are perspective drug delivery systems for oral, nasal
and transdermal applications. They represent thermodynamically stable systems with
high bioavailability of the compounds.
The purpose of the present work was to prepare SMEDDS of taxifolin and to study the
release rate of taxifolin in vitro.
A water-in-oil nanoemulsion containing 2% taxifolin, surfactant (Tween 80) and cosurfactant
(propylene glycol), oil phase (Labrafil® M 1944 CS) and water was prepared. In vitro release was investigated by the USP 28 paddle over disc method at 100 rpm (temperature
32±1°C, dissolution medium water) at modeling of transdermal application and by using
the USP 28 paddle method at 100 rpm (temperature 37±1°C, dissolution medium 1-octanol
and water [3]) at modeling of oral application. Concentrations of taxifolin were analyzed
by RP-HPLC.
It was shown, that release of taxifolin from nanoemulsion is described by the equation
of first order kinetics, constants of rate release for modeling of transdermal and
oral application were 0,9306 and 0,8479h-1, accordingly. Taxifolin release from SMEDDS was about 95% in 2 and 3h in models of
transdermal and oral application, accordingly. Particle size in the nanoemulsion was
evaluated upon dilution with aqueous media as described by [4]. It was concluded that
bioavailability of taxifolin was enhanced greatly by SMEDDS. Alternative mechanisms,
such as improved lymphatic transport pathway, other than improved release may contribute
to enhancement of bioavailability of taxifolin.
References: [1] Middleton E. et al. (2000) Pharmacol. Rev. 52: 673–751. [2] Silva M.M. et al.
(2002) Free Radical Res. 36: 1219–1227. [3] Karlina M. et al. (2006) Voprosy Biol.
Med. Pharm. Chem. 9: 42–46. [4] Ghosh P.K. et al. (2006) AAPS Pharm Sci Tech, 7: art.
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