Fast-dissolving mucoadhesive microparticulate delivery system containing piroxicam

We have studied the feasibility of preparing fast-dissolving mucoadhesive microparticulate delivery systems containing amorphous piroxicam to improve drug residence time on sublingual mucosa and drug dissolution rate. Two new mucoadhesive carriers, Eudragit((R)) L100 (EuLNa) and Eudragit((R)) S100 (EuSNa) sodium salts, both characterized by a fast intrinsic dissolution rate, have been selected. Microparticles containing piroxicam and EuLNa (series 1) or EuSNa (series 2) in ratios from 15/85 to 85/15% (m/m) were prepared by spray drying. The morphology and physical state of the microparticles and the effect of the microparticle composition on the piroxicam release and mucoadhesion were investigated. Piroxicam loaded into the microparticles was found to be in the amorphous form at all drug/copolymer ratios. This feature was ascribed to the presence of an H-bond between the NH of piroxicam and a CO of the copolymers. The formation of solid solutions improved the dissolution rate and the apparent drug solubility. The mucoadhesive properties were affected by the drug/copolymer ratio and in series 2 the microparticles containing more than 50% (m/m) of piroxicam did not show mucoadhesive properties. The delivery system made of piroxicam and EuLNa in the ratio 70/30% (m/m) appears to be the most promising because it contains the lowest amount of polymer able to confer mucoadhesive properties and increase apparent drug solubility.