Solid dispersions of nitrofurantoin, ethotoin, and coumarin with polyethylene glycol 6000 and their coprecipitates with providone 25,000.

The influence of two linear polymers, polyethylene glycol 6000 and povidone 25,000, on the dissolution rate of three poorly soluble drugs, nitrofurantoin, ethotoin, and coumarin, was studied. Povidone 25,000 produced better drug solubilization than polyethylene glycol 6000 with the drug-polymer ratios studied, and an increase in the weight fraction of either polymer gave more rapid dissolution. TLC and IR studies ruled out any interaction between the drugs and polyethylene glycol 6000. IR spectrophotometry provided evidence that there was complex formation between nitrofurantoin and povidone 25,000, probably via hydrogen bonding.