Enhancement of dissolution of piroxicam using hydrophilic polymers by microsphere technology

The areas of current interest in pharmaceutical technology which have a significant impact on clinical therapy are enhancement of solubility, dissolution rate and bioavailability of insoluble and poorly soluble drugs and development of immediate and controlled release drug delivery systems. Many of the modern drugs belong to class II under biopharmaceutical classification system (BCS) which are characterized by low solubility and high permeability and exhibit low and variable dissolution and bioavailability and pose problems in the design of immediate and controlled release products, due to their insoluble character.;Piroxicam (anti-inflammatory agent) belongs to BCS class II and requires enhancement in solubility and dissolution rate for increasing its oral bioavailability. The dissolution rate of piroxicam was enhanced using microsphere technology employing hydrophilic polymers HPMC El5 LV, Na-CMC. Piroxicam microspheres were prepared by phase inversion microencapsulation method. The microspheres gave rapid and higher dissolution of piroxicam when compared to pure drug and followed first order kinetics. A 2.1 fold and 1.8 fold increase in dissolution efficiency was observed with microspheres of HPMC, Na-CMC respectively. Time for 50% of the drug to dissolve was 45, 20 and 17.5 minutes for pure drug, Na-CMC microspheres and HPMC microspheres respectively. The X-ray diffraction study has shown a halo pattern in which diffraction peaks of drug have disappeared indicating the drug in HPMC microspheres was in amorphous state but in case of Na-CMC microspheres some peaks of piroxicam were seen due to presence of some crystallinity. The DSC data confirmed that piroxicam was amorphous in HPMC microspheres and in case of Na-CMC microspheres a melting transition endothermic peak of piroxicam was present on DSC thermogram due to partial conversion into amorphous state. FTIR data further confirmed better conversion of drug into amorphous structure in HPMC microspheres than in Na-CMC microspheres. Microsphere technology could be considered as a promising system for drug delivery applications to enhance the dissolution rate of piroxicam, a poorly soluble drug by using hydrophilic polymers of which HPMC E15 LV has shown better results than Na-CMC.