Sensitive LC determination of piroxicam after in vitro transdermal permeation studies.

A direct, very sensitive, simple and rapid high-performance liquid chromatographic (HPLC) method for the determination of piroxicam, with tenoxicam as internal standard, has been developed and validated. Samples were chromatographed on a 5 microm Scharlau C(18) column. The mobile phase was a mixture of acetonitrile-acetic acid 4% (pH 2.8) (45:55, v/v). Detection was at 354 nm and the run time was 7 min. The limit of detection was 0.025 microg/ml. The detector response was found to be linear in the concentration range 0.05-9 microg/ml. This HPLC assay has been applied to measure the 'in vitro' percutaneous permeation of piroxicam through abdominal hairless rat skin, using Franz-type diffusion cells, in order to obtain the concentration-time profiles of piroxicam.