Effect of the Essential Oil ofEryngium caeruleumon Percutaneous Absorption of Piroxicam through Rat Skin

Recently, in order to improve drug permeation trough the skin, penetration enhancers have attracted a great deal of interest in increasing percutaneous absorption. Natural compounds like terpenes have been suggested as promising non-toxic, non-irritating transdermal penetration enhancers. This investigation aimed to study the effect of different concentrations of essential oil of Eryngium caeruleum on the transdermal absorption of piroxicam. Piroxicam solubility was evaluated and several formulations were developed. The stable gel was chosen and enhancing effects of essential oil with different concentrations (0.25–5.0 % w/w) on the permeation of piroxicam were evaluated using Franz diffusion cells fitted by rat skin. PEG 200: buffer 7.4 (40:60) were used as suitable solvent for selected formulation. The results showed that in all cases (formulations containing plant essential oil) the greatest enhancement of the skin transport occurs at the highest concentration of the enhancer (P < 0.01). There is no direct linear relationship between E. caeruleum essential oil and the permeation rate. The most outstanding penetration enhancer was plant essential oil in 5 % w/w, providing an almost 8.56-fold increase in permeability coefficient of piroxicam. E. caeruleum essential oil have shown ability to enhance the permeation of piroxicam across rat skin. Based on anti-inflammatory and analgesic effects of this genus, and traditional uses, the enhancer effects of E. caeruleum will be emphasized.