(R)-Flurbiprofen is a member of the 2-aryl propionic acid group of nonsteroidal anti-inflammatory drugs (NSAIDs). Only a small amount (<5%) of (R)-enantiomer is converted to the (S)-enantiomer in rats and humans; therefore, the biological effects are specific to each enantiomer. Although inactive as an inhibitor of cyclooxygenase (COX), this enantiomer reduces inflammation through inhibition of NF-κB and AP-1 activation. (R)-Flurbiprofen has also been shown to suppress prostate tumor cells by inducing p75NTR protein expression. (R)-Flurbiprofen inhibits the enzyme γ-secretase thereby preventing the formation of the amyloid β peptide (Aβ42) from amyloid β precursor protein (APP). Before being dropped as a drug candidate, (R)-flurbiprofen advanced to Phase III clinical trials, the first drug candidate to advance to late stage trials for the treatment of mild Alzheimer’s disease.
