Ibuprofen is a non-steroidal anti-inflammatory drug with diverse biochemical actions, most notably inhibiting COX-1 and COX-2 (IC50s = 2.6 and 1.53 μM, respectively). It is commonly synthesized as a racemic mixture of (S) and (R) isomers . (R)-Ibuprofen is an enantiomer that is generally not considered a COX inhibitor and is instead thought to be involved in pathways of lipid metabolism as it is incorporated into triglycerides along with fatty acids. The (R) enantiomer can, however, inhibit NF-κB activation (IC50 = 121.8 μM) in response to T-cell stimulation as well as block superoxide formation, β-glucuronidase release, and LTB4 generation by stimulated neutrophils (IC50 values range from 40-100 μM). 50-60% of (R)-ibuprofen is inverted to (S)-ibuprofen in humans after oral administration.
