Enhancement of dissolution and bioavailability of piroxicam in solid dispersion systems.

Solid dispersion systems of water-insoluble piroxicam in polyethylene glycol (PEG) 4000 and in urea were prepared by fusion and solvent methods and were characterized in this study. The in vitro dissolution studies showed that the dispersion systems containing piroxicam and PEG4000 or urea gave faster dissolution than the corresponding simple mixtures. The differential scanning calorimetry (DSC) study indicated that the piroxicam-PEG system prepared by the fusion method is a solid dispersion, while the piroxicam-urea system prepared by the solvent method is likely to be a solid solution of piroxicam in urea. The storage testings showed that all dispersions were stable, except that uptake of water during storage may occur in the PEG system. A single-dose study with rabbits showed that the dispersion systems provided statistically significant to a higher extent and rate of bioavailability than the corresponding physical mixture (p < 0.05).