Binary melting phase diagrams of nifedipine-PEG 4000 and nifedipine-mannitol systems

The phase diagrams of nifedipine-polyethylene glycol (PEG) 4000 and nifedipine-mannitol systems have been determined. Heating experiments on thermodynamically equilibrated co-melts revealed eutectic behaviour for nifedipine-PEG 4000 mixtures, with the composition of the eutectic point between 40 and 45%w/w of nifedipine. These observations were supported by optical and hot stage microscopy. Nifedipine and mannitol were negligibly miscible in the solid-state, behaving as a binary system with monotectic characteristics. Application of phase diagrams to the production of solid dispersions is shown to be rational, since they provide valuable information on the state of the binary systems under preparation. This revised version was published online in July 2006 with corrections to the Cover Date.