fluoroquinolone

Fluoroquinolones are broad-spectrum synthetic antibiotics such as ciprofloxacin, levofloxacin and moxifloxacin. They are absorbed well by mouth, reach high levels in many tissues, and cover a wide range of bacteria, which once made them popular all-purpose drugs. That same convenience led to overuse, and they are now reserved more carefully.

They kill bacteria by inhibiting two enzymes essential for managing DNA: DNA gyrase and topoisomerase IV. These enzymes untangle and re-coil the bacterial chromosome during replication; block them and the DNA strands snap and the cell dies, making fluoroquinolones bactericidal. Because the targeted enzymes are distinct from the human equivalents, they exemplify selective toxicity, though the resemblance is closer than for some other classes.

Fluoroquinolones carry a notable burden of serious adverse effects, which is why regulators have issued strong warnings. They can cause tendon inflammation and rupture, peripheral nerve damage, central nervous system effects, QT-interval prolongation and aortic problems, some of which may be lasting. For this reason they are generally not recommended for mild infections when safer options exist, and are best kept for situations where their broad reach is genuinely needed.