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Weiche Materie Poster: Do., 13:00–15:30 D-P354
QENS and nuclear magnetic resonance studies of Q10-nanodispersions
Christoph Smuda 1 , Tobias Unruh 1
1 Technische Universität München, Forschungsneutronenquelle Heinz Maier–Leibnitz
FRM II, Lichtenbergstraße 1, 85747 Garching, Germany
In recent years it has become evident that the development of new drugs alone is not
sufficient to ensure progress in drug therapy. Today there are many drugs which in
spite of their high pharmacological potential cannot be administered using standard
formulations because of e.g. side effects, targeting problems or adverse release effects.
Reasons can be: poor drug solubility in aqueous solutions, chemical instability of the
drug, insufficient drug concentration due to poor absorption, rapid metabolism and
elimination.
A promising strategy to overcome these problems involves the development of suitable
drug carrier systems. The in vivo-fate of the drug is no longer mainly determined by
the properties of the drug, but by the carrier system, which should permit a controlled
and localized release of the active drug according to the specific needs of the therapy
[1].
We examine colloidal drug carrier systems like nanodispersions and solid lipid nanoparticles
(SLN). The dispersions are prepared by high pressure homogenization of a predispersion
of the molten lipid with water and emulsifiers.
The heart-protecting drug ubidecarenone (coenzyme Q10) is of special interest due to
its biological effects in the human body. Coenzyme Q10 is an antioxidant with very
poor solubility in aqueous media and is naturally found throughout the body.
High supercooling of Q10 and the formation of stable Q10-containing nanodispersions
have been observed. The virtual insolubility of Q10 in water results in a very poor
peroral bioavailability from conventional dosage forms. Processing into nanoparticles
of supercooled melts lead to improved bioavailability [2].
Q10-nanodispersions were investigated by means of QENS and pulsed field gradient
(PFG) nuclear magnetic resonance (NMR) for determination of self diffusion coefficients
and internal motions like methyl group rotations. These methods provide complementary
data: PFG-NMR allows the measurement of self diffusion coefficient of the
nanoparticle and QENS the determination of the diffusion coefficient of the drug inside
the nanoparticle.
[1] W. Mehnert et al., Adv. Drug Del. Rev. 47 (2001) 165.
[2] K. Westesen, Colloid Polym. Sci. 278 (2000) 608.