Preparation and in vitro evaluation of self-microemulsifying drug deliverysystems containing idebenone

A new self-microemulsifying drug delivery system (SMEDDS) was developed to increase the dissolution rate, solubility, and, ultimately, bioavailability of a poorly water soluble drug, idebenone. Pseudoternary phase diagrams we re used to evaluate the self-microemulsification existence area, and the re lease rate of idebenone was investigated. The mixtures consisting of Labraf ac hydro or Labrafil 2609 (HLB values > 4) with the surfactant (Labrasol co ntaining 80% Transcutol) and cosurfactant (Plurol oleique WL 1173) were fou nd to be optimum formulations. Using the SMEDDS formulations of 5% to 20% o f Labrafac hydro or Labrafil 2609 in combination with the surfactant/cosurf actant mixing ratio of 3, the microemulsion existence field was wider compa red to the other SMEDDS formulations due to high affinity for the continuou s phase. The in vitro dissolution rate of idebenone from SMEDDS was more th an twofold faster compared with that of tablets. The developed SMEDDS formu lation can be used as a possible alternative to traditional oral formulatio ns of idebenone to improve its bioavailability.