Dry Adsorbed Emulsions: An Oral Sustained Drug Delivery System

Abstract

The oral sustained drug delivery system “dry adsorbed emulsion” was defined as an organized dispersion of hydrophilic and hydrophobic particles whose structure was initiated by the structure of a water‐in‐oil (W/O) emulsion. Sodium salicylate was dissolved in the aqueous phase of the primary W/O emulsion as an active drug. The aqueous phase of the W/O emulsion was absorbed by a hydrophilic silica and then a hydrophobic silica was added to the preparation to obtain a stable and solid pulverulent form. The physicochemical structure of a “dry adsorbed emulsion” was described and observed by electron microscopy. The effect of different oils, castor oil and a silicone oil, on the sustained drug release was studied at two different pH values, 1.2 and 7.4, to simulate the gastric and intestinal medium, respectively. The properties of these forms were retained for more than one year at room temperature storage.