Studies On Piroxicam Organogels

Organogels are semisolid systems consisting of organic continuous phases. When topically applied, they are also termed as olegels or lipogels. Organogels have significant advantages and may be used as potential transdermal carriers.We prepared amphiphilogels, lecithin organogel, Pluronic lecithin organogel and Carbopol hydrogel. We evaluated rheological, in vitro drug release and transdermal permeability properties of organogels and Carbopol hydrogel with piroxicam and piroxicam -monoethanolamine as model drugs. We also investigated the tissues distribution of lecithin organogel, Pluronic lecithin organogel and cabopol hydrogel with piroxicam as the model drug.The rheological parameters of these gels were measured with cone-plate configuration rheometer under oscillation mode and within linear viscoelastic range. We found that amphiphilogels and Pluronic lecithin organogel had low phase angles (<30°) and their elastic modulus and viscous modulus were frequency-independent, which exhibited typically rheological characters of gels; at room temperature, lecithin organogel showed partial characters of viscous fluids (higher phase angles). Except for lecithin organogel, other organogels and Carbopol hydrogel had shear-thinning property. These organogels had suitable phase transition temperatures and good spreadability.In vitro drug release and transdermal permeability of model drugs from various organogels were performed by modified Franz cell method with nylon and rat full-skin as the penetrate membranes, respectively. Pluronic lecithin organogel exhibited the highest accumulative drug release, and the release percents were 81.56±3.09% for piroxicam and 66.21±1.74% for piroxicam- monoethanolamine at 48h. The highest percents of transdermal permeation were observed from lecithin organogel (43.52±4.17% for piroxicam and 10.44±0.24% for piroxicam-monoethanolamine at 48h, respectively).We investigated the tissues distribution of Carbopol hydrogel, Pluronic lecithin organogel and lecithin organogel after topical application to Wistar rat with piroxicam as the model drug. We found similar tissues distribution properties for these organogels and Carbopol hydrogel tested. The highest concentration of piroxicam in skin was that of Pluronic lecithin organogel (53.51±28.90μg/g), and concentrations of piroxicam in deep tissues (muscle and joint) of Pluronic lecithin organogel were also higher. The drug concentrations in local tissues on applied side were higher than that of tissues on the Contralateral side. Tissues (muscle and joint) /Plasma ratios on applied side were higher than that of the Contralateral side, and the presence of two peaks in tissues and underlying tissues had been observed. There were two absorptive routes: direct penetration by which drug was transferred from tissues of higher concentrations to tissues of lower concentrations, and redistribution of drug through topical blood capillary system.Organogels have suitable rheological properties, powerful drug-loading and transdermal permeability, which can be potential carriers for transdermal drug delivery.