Preparation and evaluation of self-microemulsifying drug delivery system of oridonin

The objective of this study was to develop self-microemulsifying drug delivery system (SMEDDS) to enhance the oral bioavailability of the poorly water-soluble drug, oridonin. The influence of the oil, surfactant and co-surfactant types on the drug solubility and their ratios on forming efficient and stable SMEDDS were investigated in detail. The SMEDDS were characterized by morphological observation, droplet size and zeta-potential determination, cloud point measurement and in vitro release study. The optimum formulation consisted of 30% mixture of Maisine 35-1 and Labrafac CC (1: 1), 46.7% Cremopher EL, and 23.3% Transcutol P. In vitro release test showed a complete release of oridonin from SMEDDS in an approximately 12 It. The absorption of oridonin from SMEDDS showed a 2.2-fold increase in relative bioavailability compared with that of the suspension. Our studies demonstrated the promising use of SMEDDS for the delivery of oridonin by the oral route. (C) 2007 Elsevier B.V. All rights reserved.