Abstract:
Nitrendipine (NDP), a dihydropyridines calcium antagonist which has a very low solubility in vitro was used as a poorly water-soluble model drug. The percutaneous permeation of nitrendipine was investigated in rat skin after application of a water–propylene glycol (50:50% v/v) using a diffusion cell technique. The effect of various surfactants such as sodium lauryl sulphate (SLS), benzalkonium chloride and Tween 80 with different concentrations on skin permeability were evaluated. Flux, Kp, lag time and enhancement ratios (ERs) of nitrendipine were measured over 12 h and compared with that of control sample. Furthermore, solubility in presence of surfactants was determined. The in vitro permeation experiments with rat skin revealed that the surfactant enhancers varied in their ability to enhance the flux of nitrendipine and the flux of benzalkonium chloride provided the greatest enhancement for nitrendipine flux (5.858±0.145 μg/cm²/h, 3 fold over control) at 1% w/w of the surfactant. SLS at a concentration of 5% w/w (the highest concentration) exhibited the greatest increase in flux of nitrendipine compared with control (6.103±0.221 μg/cm²/h, 3.5 fold over control). Tween 80 at a concentration of 1% w/w exhibited significant increase in flux of nitrendipine compared to control (5.607±0.187, 1.9 fold over control). The results also showed that the highest ER was obtained in presence of 1% w/w surfactant with the exception of SLS. The increase in flux at low enhancer concentrations is normally attributed to the ability of the surfactant molecules to penetrate the skin and increase its permeability. The results showed that the nature of enhancer greatly influences cutaneous barrier impairment. The surfactants have shown ability to enhance the permeation of nitrendipine across rat skin.

Keywords: Nitrendipine, Tween 80, Sodium Lauryl Sulfate, Permeability.