Effect of enhancers on the in vitro percutaneous absorption of piroxicam from compounding formulations

Abstract

Formulations of piroxicam in Lanette® (L) or Net Fs® (N) vehicles, with or without permeation enhancers, the ethanol (E) or propylene glycol (P) were developed. The piroxicam permeation through porcine ear skin, in a Franz Cell was evaluated, comparing with a commercial product. The permeate was analyzed by high performance liquid chromatography (HPLC) using a 5 mm C18 column with mobile phase methanol:phosphate buffer (60:40), at 354 nm and the run time of 10 min. This method was validated and the limit of quantification was 0.138 mg/mL, with linearity over 0.02-5 µg/mL, without endogenous skin interference. The order of piroxicam permeation after 24 h was: LE >; L>; Feldene® >; N >; LP >; NP >; NE. The L based formulations showed greater piroxicam permeation compared with N based formulations, particularly up to 10 h of experiment. The ethanol enhancer provided the highest piroxicam permeation. The commercial product shows a different behavior, providing piroxicam permeation almost after 10 h. These results show the development of effective, simple and economic percutaneous formulations of piroxicam allowing the choice of formulations for higher or lower piroxicam permeation.