In Vitro: Naproxen etemesil is a lipophilic, non-acidic, inactive prodrug of naproxen that is hydrolysed to pharmacologically active Naproxen once absorbed. Naproxen is a well known nonsteroidal anti-inflammatory drug. Naproxen is approximately equipotent inhibitor of COX-1 and COX-2 in intact cells with IC50s of 2.2 μg/mL and 1.3 μg/mL, respectively.
In Vivo: Naproxen exerts an anti-inflammatory and antifibrotic effect in mouse model of bleomycin-induced lung fibrosis. Naproxen also downregulates TGF-β levels and Smad3/4 complex formation. Naproxen is shown to inhibit the time-courses of pain, fever and PGE2 with similar potencies (IC50=27, 40, 13 μM).