In Vitro Percutaneous Absorption of Tenoxicam from Pressure- sensitive Adhesive Matrices across the Hairless Mouse Skin

To investigate the feasibility of developing a new tenoxicam plaster, the effects of vehicles and penetration enhancers on the in vitro permeation of tenoxicam from a pressure-sensitive adhesive (PSA) matrices across the dorsal hairless mouse skin were studied. Vehicles employed in this study were propylene glycol (PG)-oleyl alcohol (OAI), PG-oleic acid (OA), and diethylene glycol monoethyl ether (DGME)-propylene glycol monolaurate (PGML) cosolvents with/without fatty acids. In this study, amines such as triethanolamine (TEA) and tromethamine (TM) were additionally used as a solubilizer. Among PSAs used, Duro-Tak® 87-2510 showed much higher release rate than either Duro-Tak® 87-2100 or Duro-Tak® 87-2196. The relatively high flux rate was obtained with the formulation of DGME-PGML (40:60, v/v) with 3% OA and 5% TM, and the flux increased as a function of the dose; the initial flux up to 12 h was 4.98 ± 1.38 μg/cm²/h at the tenoxicam dose of 50 mg/70 cm². This flux was much higher than that of a commercial piroxicam patch (Trast®) (1.24 ± 0.73 μg/ cm²/hr) with almost only one-third that of the commercial patch. Therefore, these observations indicated that these composition of tenoxicam plaster may be practically applicable.