What is the role of class II NSAIDs in the etiology of cyclooxygenase (COX) deficiency?

Updated: Feb 19, 2019
  • Author: George T Griffing, MD; Chief Editor: George T Griffing, MD  more...
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Answer

Class II NSAIDs, which include indomethacin, flurbiprofen, meclofenamate, and diclofenac, are defined as competitive, time-dependent COX inhibitors. Their interaction with COX active sites is laggard relative to class I inhibitors. After initial formation of the EI complex, the inhibitor causes a slow, but reversible, conformational change in the protein to form an EI* complex. This non–covalently bound, semistable complex is less susceptible to proteases and dissociates from COX active sites at a slower rate than do EI complexes.

Several studies have indicated that different class II inhibitors possess different k2 and k-2 values for COX-1 and COX-2 active sites based on in vivo selectivity. Although the biochemical mechanism of EI* complex formation is unknown, researchers attribute the kinetic properties of class II inhibitors to structural differences.


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