Gels and microemulsions are classes of dosage forms that have emerged as promising drug delivery system for the delivery of various drugs. The objective of this study is to prepare tenoxicam, a non-steroidal anti-inflammatory drug (NSAID), topical gel formulae using cellulose derivatives (Sodium carboxymethyl cellulose (NaCMC), Methyl cellulose (MC), Hydroxypropyl methyl cellulose (HPMC), Hydroxy ethyl cellulose (HEC), and Hydroxy propyl cellulose (HPC)) as gelling agents and to prepare topical microemulsions, microemulsion-gel formulae using (labrasol, tween 80 and tween 20) mainly as surfactants, (Oleic acid and isopropylmyristate (IPM)) as oils. Fifteen gel formulae were prepared (F1-F15) and evaluated for physical properties (color, clarity, homogeneity), rheological properties, pH measurements, in vitro drug permeation through cellulose dialysis membranes and in vitro drug permeation studies through natural rat skin. The gel formulae which showed best physical properties and highest drug permeation were chosen in the preparation of microemulsion-gel formulae. Ten microemulsion formulae were prepared (M1-M10) and those with the broadest microemulsion region as shown by the phase diagrams and those with the maximum loading capacity of tenoxicam were chosen to be formulated into microemulsion-gel formulae. Nine microemulsion-gel formulae were prepared (S1-S9) and evaluated for physical properties (color, clarity, homogeneity), rheological properties, pH measurements, in vitro drug permeation through cellulose dialysis membranes and in vitro permeation studies through natural rat skin. In vivo rat-paw edema tests were carried out to evaluate the activity of gel formulae and microemulsion-gel formulae which showed maximum tenoxicam permeation through rat-skin, and compared them with market product Feldene® gel (Piroxicam 0.5%) The obtained results showed that S3 microemulsion-gel formula possesses the maximum drug permeation as well as anti-inflammatory activity which proved to be even greater than Feldene® gel. Therefore, S3 is effectively promising as topical anti-inflammatory dosage forms, due to the permeation enhancement caused by using microemulsions together with the gel base.
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