Self-Emulsifying Drug Delivery Systems for Improving Oral Absorption of Ginkgo Biloba Extracts

Abstract

Self-emulsifying drug delivery systems (SEDDS) are mixtures of oils, surfactants, and cosurfactants, which are emulsified in aqueous media under conditions of gentle stirring and digestive motility that would be encountered in the gastrointestinal tract. We found that SEDDS could efficiently improve oral absorption of the sparingly soluble drugs by rapid self-emulsification and subsequently dispersion in the absorption sites. Ginkgo biloba extract (GBE) has become a widely used herbal remedy for increasing cognitive function in elderly people. The main purpose of our work is to prepare SEDDS for improving oral absorption of GBE. Pseudoternary phase diagrams were constructed to identify the efficient self-emulsification region, and particle size distributions of resultant emulsions were determined. The optimized formulation for bioavailability assessment consisted of 45% Tween 80-Cremophor EL35 (1:1, w/w), 10% 1, 2-propanediol, and 45% ethyl oleate. The mean droplet size distribution of the optimized SEDDS was ∼100 nm when diluted with 500-fold volume of the distilled water. The in vitro dissolution rates of the active components of GBE SEDDS form were significantly faster than those of the GBE tablets. After single oral administration of 800 mg GBE as SEDDS or tablets to fasted dogs, the relative bioavailability of SEDDS for bilabolide and ginkgolide A and B was 162.1, 154.6, and 155.8% compared with the reference tablets, respectively. Our results suggested the potential and promising use of SEDDS for the efficient delivery of the sparingly soluble drugs or traditional Chinese medicines, such as GBE by oral administration.

Keywords:

• Self-Emulsifying Drug Delivery Systems
• Ginkgo Biloba Extracts
• Bioavailability

We are grateful for the financial support by the National High Technology Research and Development Program of China (863 Program, no. 2004AA2Z3250) and by the Education Department of Liaoning Province, no. 2004D266.