Abstract: Objective To investigate the drug delivery and mechanism of topical administration of piroxicam in rats. Methods Four milligrams of piroxicam were administered to Wistar rats by either oral or topical routes. The drug concentrations in plasma, local tissues were determined by HPLC. Results After oral application, the Tjoint/Plasma and Tmulcle/Plasma ratios kept unchanged. During most of the experimental time(0-24 h), the values varied between 0.06 and 0.2. In contrast,the Tjoing/Plasma and Tmuscle/Plasma ratios after local application varied from 0.2 to 1.26 and from 1.89 to 5.4 respectively and were much higher than the ones by oral application. Conclusion The results showed that most piroxicam reaching the local deep tissues was attributed to the direct penetration and topical delivery is superior to oral application when the drug's target is local tissues under skin.

Key words: Pharmacokinetics, Pharmacokinetics, Piroxicam, Piroxicam, Topical drug delivery, Topical drug delivery, Oral administration, Oral administration