The aims of this study are to prepare and characterize a microemulsion-based hydrogel containing celecoxib (CLX) for transdermal delivery. Pseudo-ternary phase diagrams containing 0.74% (w/w) CLX were constructed usingawater titration method. The mixture exhibiting the largest area of the microemulsion region was selected. The effect of the ratio of oil to themixtureof surfactant and cosurfactant (O/Smix) on in vitro skin permeation was investigated. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) was employed to investigate the effects of the CLX microemulsion on skin. Rheological measurementswereperformed, and in vitro skin permeation of the CLX microemulsion-based hydrogel was tested.

Based on pseudo-ternary phase diagrams, the Capryol PGMC-Tween 80-Transcutol P mixturewasselected because it had the largest microemulsion area. A CLX microemulsion with O/Smix ratio of 3/7 was chosen because it had the greatest in vitro skin permeation. ATR-FTIR demonstrated that CLX microemulsion led to a transition in the alkyl chain of SC lipids and permeated hairless mouse dorsal skin. TheCLXmicroemulsion-based hydrogel was elastic and suitable for application to skin. The incorporation of a gelling agent controlled the drug release of CLX, implying improved therapeutic effects of CLX for arthritis.