Self-double-emulsifying drug delivery system (SDEDDS): A new way for oral delivery of drugs with high solubility and low permeability

Water-in-oil-in-water (w/o/w) double emulsions are potential for enhancing oral bioavailability of drugs with high solubility and low permeability, but their industrial application is limited due to the instability. Herein, we developed a novel formulation, self-double-emulsifying drug delivery systems (SDEDDS) by formulating mixtures of hydrophilic surfactants and water-in-oil (w/o) emulsions, which were easier to be stable through formulations optimization. SDEDDS can spontaneously emulsify to water-in-oil-in-water (w/o/w) double emulsions in the mixed aqueous gastrointestinal environment, with drugs encapsulated in the internal water phase of the double emulsions. We employed SDEDDS to improve the oral absorption of pidotimod, a peptide-like drug with high solubility and low permeability. The optimized pidotimod-SDEDDS were found to be stable up to 6 months under 25 degrees C. Plasma concentration-time profiles from pharmacokinetic studies in rats dosed with SDEDDS showed 2.56-fold (p < 0.05) increased absorption of pidotimod, compared to the pidotimod solution. Histopathologic studies confirmed that SDEDDS exerted absorption promoting effect without serious local damages. These studies demonstrate that SDEDDS may be a promising strategy for peroral delivery of peptide and peptidomimetic drugs. (C) 2011 Elsevier B.V. All rights reserved.