Abstract
Screening of surfactants was carried out to develop an oil in water (o/w) emulsion type new vehicle for a soft gelatin capsule (SGC), using polyethyleneglycol 400 (PEG 400) as hydrophilic phase and medium chain triglyceride (Miglyol 810[○!R]), propyleneglycol dicaprylate (Sefsol 228[○!R]) or soybean oil as hydrophobic phase (PEG 400 : hydrophobic phase : surfactant=87 : 10 : 3) and by means of simple homogenization.Polyoxyethylene (20) cetylether (BC-20TX[○!R]), which can form homogeneous and viscous white gels using the above hydrophilic and hydrophobic phase combination, was selected as a model surfactant for developing the new vehicle. Using Miglyol 810[○!R] as hydrophobic phase, a model new vehicle formulation (PEG 400 : water : Miglyol 810[○!R] : BC-20TX[○!R]=77 : 10 : 10 : 3) was prepared, and its physicochemical properties were evaluated.The particle size distribution of the new vehicle, after diluting about 3000 times with water, ranged from about 0.5 to 50μm. Furthermore, the new vehicle had thixotropic property at room temperature (about 25°C) and temperature-dependent gel-sol transforming property with the transformation temperature of about 37°C.These properties meet the requirement for encapsulation of the new vehicle in SGC and suggest that it can be expected to form the o/w emulsion state in the aqueous environment in the stomach. The rheological properties would also make it advantageous for use in other dosage forms such as suppository, cataplasm or liniment.
