Improved oral bioavailability of poorly water-soluble vorinostat by self-microemulsifying drug delivery system

Background Vorinostat is a histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) with anticancer properties. However, it is plagued by low water solubility, low permeability (BCS class IV drug), and suboptimal pharmacokinetics. The purpose of the present study was to develop a self-microemulsifying drug delivery system (SMEDDS) to enhance the oral bioavailability of vorinostat. Capryol 90, labrasol, and polyethylene glycol (PEG 400) were selected as oil phase, surfactant, and co-surfactant, respectively. The vorinostat self-microemulsifying drug delivery systems were tested for self-microemulsifying time, phase separation, effect of pH, droplet size, zeta potential, dilution study, Fourier-transform infrared (FT-IR) spectroscopy analysis, and field emission scanning electron microscopy (FESEM). A rat model in vivo pharmacokinetic study was conducted for the optimized formulation against vorinostat pure drug powder. Results The results from the characterization studies showed that the optimized formulation (F7) self-microemulsification time was 1.4 +/- 0.05 min and no precipitation or phase separation was observed. The mean droplet size, polydispersity index (PDI), and zeta potential of the optimized formulation (F7) were found to be 272.9 +/- 82.7 nm, 0.415, and - 57.2 mV, respectively. The pharmacokinetic parameters of the optimized formulation (F7) showed a 1.6-fold increase in maximum concentration (C-max) and a 3.6-fold increase in area under the curve (AUC((0-infinity))), in comparison with pure drug in suspension. Conclusions The findings suggest that SMEDDS formulation could be an effective method for increasing the oral bioavailability of vorinostat, which is poorly water soluble.