Development and Evaluation of Olmesartan Medoxomil Solid SEDDS: In Vivo Bioavailability Studies

The objective of present study was to develop solid self micro emulsifying drug delivery system (S-SEDDS) with Neusilin for enhancement of dissolution rate of model drug Olmesartan medoxomil. Olmesartan medoxomil SEDDS was prepared using oils - Captex 35, Capryol 90, Castor oil, Olive oil, surfactants - Gelucire 44/14, Kolliphor HS 15, Kolliphor RH 40, Labrasol, Tween 80, Lauroglycol, co-surfactants - PEG 400, PEG 600, Propylene glycol. Solid SEDDS were prepared using adsorbing agent Neusilin US2. A pseudo ternary phase diagram was constructed to identify the self-micro emulsification region. Further, the resultant formulations were investigated for clarity, phase separation, globule size, effect of pH and dilutions and freeze-thaw stability and found to be within the limits. The optimized SMEDDS (F6) formulation of Olmesartan contained Castor oil (Oil), Kolliphor RH 40 (Surfactant) and PEG 400 (Co-surfactant). The prepared liquid SEDDS was thermodynamically stable with good self emulsification efficiency and having globule size in nanometric range which may be physiologically stable. On the basis of different evaluation parameters F6 was found to be optimized formulation. S-SEDDS of Olmesartan medoxomil prepared with optimized SEDDS (F6) using adsorbing agent Neusilin US2 by adsorption technique have good flow property and drug content. This optimized formulation (F6) was converted in to solid SEDDS by adding required quantity of Neusilin US2 as adsorbing agent used for in vitro dissolution and bioavailability assessment. Results of SEM demonstrate that spherical S-SEDDS can be obtained without agglomeration. In vivo studies revealed that the oral bioavailability of Olmesartan medoxomil from solid SEDDS was 2.3-fold higher compared to that of Olmesartan suspension in rats, suggesting a significant increase (p < 0.05) in oral bioavailability of Olmesartan medoxomil from solid SEDDS. Hence it was concluded that S-SEDDS can be efficiently formulated by adsorption technique using Neusilin US2 as solid carrier to enhance dissolution rate of poorly soluble drug such as Olmesartan medoxomil.