HPLC evaluation of diclofenac in transdermal therapeutic preparations

High-performance liquid chromatography (HPLC) was selected for analytical e valuation of sodium diclofenac in original transdermal therapeutic preparat ions containing adjuvant substances (capsaicin, hyoscyamine). After isolati on from laminated adhesive patches, diclofenac was analysed on columns with reversed phase, using the mobile phase ethanol and phosphate buffer (pH 6. 5) with an addition of tetrabutylammonium iodide and detection at 284 nm. N ot only the total amount of diclofenac in the patch was evaluated, but HPLC methodology was also employed to select a suitable acceptor medium for per meation experiments. In patches manufactured in the tested series, HPLC was also employed to examine the release of diclofenac and its in vitro permea tion through the human skin. (C) 2001 Elsevier Science B.V. All rights rese rved.