Non-selective COX inhibitor. The IC50 values for human recombinant COX-1 and -2 are 0.6-4.8 µM and 2.0-28.4 µM, respectively. Naproxen is a potent, non-steroidal, non-selective anti-inflammatory compound that acts as a Cox (cyclooxygenase) inhibitor, and inhibits both Cox-1 and Cox-2. Research indicates that the S-naproxen is a more active form than the R-naproxen. The S-naproxen enantiomer was observed to inhibit platelet aggregation, and both enantiomers decrease production of thromboxane B2. Naproxen has been demonstrated to block Abeta fibril growth and form a complex with copper (II).