The
quinolones are generally considered to be inhibitors of CYP1A2; however, it should be noted that they varying in the strength of their effect.
Quinolones that are more potent inhibitors of CYP1A2 are likely to have greater effects on substrates of this isoenzyme, and therefore their use seems more likely to be associated with greater
clinical consequences. Caffeine is used as a probe substrate for CYP1A2. Therefore the magnitude of the effect the
quinolones have on
caffeine can be used as a guide to the strength of their effect on CYP1A2. The interactions of the
quinolones with
caffeine suggests that enoxacin has the greatest effects, ciprofloxacin and pipemidic acid have moderate effects, while
gatifloxacin,
levofloxacin,
lomefloxacin, moxifloxacin,
nalidixic acid,
norfloxacin,
ofloxacin, pefloxacin, rufloxacin and sparfloxacin only inhibit CYP1A2 to a small or clinically irrelevant extent.