Preparation and evaluation of drug release and stability of emulsified ointment base for burn

Physicochemical properties, drug release and stability of polymyxin B sulfate in an ointment prepared for the treatment of burn with use of o/w type emulsified base were studied. This ointment showed the equal consistency and spreadability to those of the commercial emulsified base for burn, and the washing-out time was appreciably shorter than that. The rate of the release of polymyxin B sulfate from the ointment was higher in the order of macrogol, emulsified and hydrophilic ointment. When polymyxin B sulfate were prepared with any of 3 ointment bases, their potencies lowered by about 10% when they were stored at 37°C for 2 months, but they were almost stable when stored at room temperature for a month