Utility of a novel self-emulsifying system for a lipophilic drug with low oral bioavailability
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Date
2006
Authors
Wai Peng, Choy
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Abstract
The present study was conducted to formulate a self-emulsifying system (SES) for
enhancing the systemic absorption of poorly bioavailable lipophilic drugs, using
ubiquinone as the model drug. A simple high performance liquid chromatographic
method with the required specificity, precision and accuracy was first developed for
quantification of ubiquinone in rat and human plasma.
Several aspects leading to the formulation of a suitable SES for ubiquinone were first
studied. They included the determination of the ubiquinone lipid solubility (log
P octanoltaqueous), evaluation of various potential oily vehicles, type and concentrations of
surfactants, the self-emulsification efficiency and emulsion droplet sizes of various
surfactant and vehicle combinations and finally the drug loading and chemical stability
of ubiquinone in the self-emulsifying (SE) formulations. From these studies, an
optimised SE formulation comprising a 9:1 w/w mixture of a-linolenic acid and
Cremophor® EL loaded with 60 mg/g of ubiquinone was found to have the most
satisfactory in vitro performance.
An in vivo study conducted using Sprague-Dawley rats revealed that the oral
bioavailability of the optimised SE formulation was comparable to that of a
commercially available self-microemulsifying (SME) ubiquinone formulation, Q-Gel®
Forte. Another in vivo study was also carried out using healthy human volunteers,
comparing the optimised SE formulation to Q-Gel® Forte as well as another
commercially available oily suspension of ubiquinone, Bio-Quinone. It was found that
the extent of bioavailability of the optimised SE formulation was slightly higher
(although not statistically significant) than that of Q-Gel® Forte and both were
significantly (p<0.05) higher than the oily drug suspension, Bio-Quinone.
In conclusion, the optimised SE formulation comprising a 9:1 w/w mixture of a-linolenic
acid and Cremophor® EL could self-emulsify satisfactorily and also enhance the oral
bioavailability of lipophilic drugs such as ubiquinone.
Description
Keywords
Self-emulsifing system , Oral bioavailability