An O-acetyl, S-alkyl thio ether of 2-thio phenol. It is a potent inhibitor of both COX-1 and COX-2, with IC50 values of 17 and 0.8uM for human recombinant COX-1 and COX-2 respectively. APHS exhibits 20-fold selectivity toward the inhibition of COX-2, yet it is still more potent than aspirin in the inhibition of COX-1.