Ketorolac is a pyrrolizine carboxylic acid derivative structurally related to indomethacin. It is an NSAID and is used principally for its analgesic activity and has been shown to decrease opioid requirements in post-operative patients. It does not affect consciousness or respiration but does have effects on gastric mucosa, renal perfusion, and platelet function. Ketorolac tromethamine ophthalmic solution is sold under brand name acular LS and is indicated for the reduction of ocular pain and burning/stinging following corneal refractive surgery. Ketorolac tromethamine is a racemic mixture of [-]S- and [ ]R-enantiomeric forms, with the S-form having analgesic activity. Its antiinflammatory effects are believed to be due to inhibition of both cylooxygenase-1 (COX-1) and cylooxygenase-2 (COX-2) which leads to the inhibition of prostaglandin synthesis leading to decreased formation of precursors of prostaglandins and thromboxanes from arachidonic acid. The resultant reduction in prostaglandin synthesis and activity may be at least partially responsible for many of the adverse, as well as the therapeutic, effects of these medication. Analgesia is probably produced via a peripheral action in which blockade of pain impulse generation results from decreased prostaglandin activity.

(R)- enantiomer does not exhibit COX inhibition – it was > 100-fold less active than (S)- enantiomer on both COX subtypes. (R)- enantiomer is about 60 times less potent than the (-)-S isomer in the carrageenan edema test and ca. 230 times less active than the (-)-S isomer in the mouse phenylquinone writhing assay. R-ketorolac is an inhibitor of fatty acid amide hydrolase, but not at physiological concentrations.

(S)-ketorolac is the enantiomer of ketorolac, a nonsteroidal anti-inflammatory drug. (S)-ketorolac exhibited potent cyclooxygenase (COX1 and COX2) enzyme inhibition. (S)-ketorolac is considered to be active enantiomer of racemic ketorolac.