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.