Thermal behavior and dissolution properties of naproxen from binary and ternary solid dispersions

Solid dispersions of 10% w/w naproxen (NAP) in poly(ethylene glycol) (PEG) (4000 6000 or 20,000) as a carrier with or without incorporation of anionic (sodium dodecyl sulfate; SDS) or nonionic (Tween 80; Tw80) surfactant were prepared by the melting method. Physicochemical characteristics were deter mined by differential scanning calorimetry (DSC) and X-ray diffraction anal ysis. The results of dissolution studies showed that drug dissolution prope rties were better from ternary systems than from binary systems since in th e former the wetting and solubilizing effects of surfactant and polymer wer e additive. No influence of the PEG molecular weight was found. The best pe rformance given by anionic surfactant has been attributed to several factor s, such as higher hydrophilicity, better solubilizing power, and most facil e interaction with both drug and PEG. No important changes in solid-state c haracteristics or in drug dissolution properties were found after 30 months storage for dispersions with or without surfactant. Only a slight decrease in initial drug dissolution rate was observed at the highest concentration (10% w/w) of SDS.