The dissolution rate of piroxicam, a nonsteroidal anti-inflammatory drug (NSAID) was markedly increased by the surface hydrophilization technique using Tween 80, polyvinylpyrrolidine K-30 (PVP) and polyethylene glycol 4000 (PEG). The in- vitro release of hydrophilized piroxicam from hard gelatin capsules and directly compressed dispersible tablets was tested in 0.1N HCI (pH 1.2) and phosphate buffer (pH 7.4) and was compared with two commercially available formulations of piroxicam (Feldene 20 mg capsules and Feldene 20 mg dispersible tablets, Pfizer Inc., USA). The dissolution rate of hydrophilized piroxicam was higher for PVP and PEG 4000 as compared to Tween 80. Hydrophilized piroxicam tablets gave higher dissolution rates than capsules. The drug release was found to be affected by the pH of the dissolution medium and was higher in pH 7.4 than pH 1.2.
A two-way crossover design was performed to compare the bioavailability of piroxicam. After oral administration of the selected formulations to six healthy individuals, serial blood samples were collected over 24 hours. Piroxicam was determined in the plasma by using high-performance liquid chromatograhy (HPLC). The obtained pharmacokinetic data indicated shorter t_max and higher C_max for the hydrophilized piroxicam preparations using PVP as compared to the commercial formulations of piroxicam. These results cleary indicate the usefulness of the utilized surface hydrophilization technique for the enhancement of the dissolution rate and bioavailability of piroxicam.