Formulation optimization of meloxicam sodium gel using response surface methodology

The influences of a combination of different mechanisms of penetration enhancers on the penetration absorption properties of meloxicam sodium formulations through rat skin were investigated using response surface methodology. A uniform design was applied to prepare model formulations systematically that were composed of four independent variables: the content of ethanol (x1), propylene glycol (x2), menthol (x3), and azone (x4). The penetration rate (flux) of meloxicam sodium gel through rat skin was chosen as the response which had to be higher than 400 μg/h cm2 the required flux of meloxicam gel to maintain a therapeutic concentration. The result showed optimal formulation could be obtained from this response surface methodology. Menthol had the greatest potential influence on the penetration absorption of meloxicam sodium, followed by azone, ethanol and PG, respectively. By in vivo study, meloxicam could be determined 1 h after topical administration and reached steady-state concentration at about 12 h. The bioavailability (%) of the optimal meloxicam sodium gel was about 50.1%.