Quinolone

The quinolones - or fluoroquinolones - are chemically synthesised antibiotics. The process involves synthesis of 7-chloroquinoline, which has potent bactericidal action, from chloroquine. Nalidixic acid was the first quinolone to be developed and has been used to treat certain urinary tract infections since 1962. Other derivatives have been synthesised since then. These antibiotics have antibacterial action on Escherichia coli, Proteus, and Enterobacter in particular. They are therefore used to treat many genital, urinary, gastro-intestinal, and osteo-articular infections.

How do the quinolones work?

The quinolones act on bacterial DNA. They block the synthesis of bacterial DNA by selectively inhibiting the action of two enzymes, DNA-gyrase and topo-isomerase IV.

Do they have any contraindications or precautions?

The quinolones can cause side effects, particularly neurosensory effects: faintness, and dizziness. In addition, these antibiotics can occasionally trigger severe phototoxic reactions following either mild exposure to sunlight progressing as far as post-traumatic bullae. Patients should consult their doctor promptly if they develop pain, burning, or tingling. The other major side effect is tendinitis of the ankle, and even more serious, rupture of the Achilles tendon which occurs in some patients. In rarer cases the shoulders and fingers can be affected. Patients should therefore be monitored carefully on treatment. These antibiotics are contraindicated in pregnant women and children.

Sources:

• Catholic University of Louvain, Pharmacology and pharmacotherapy of the anti-infectious agents, 25 May 2011
• INRS, Photosensitisation, skin cancers, and occupational exposure to ultra-violet, 2004, accessed on 26 May 2011
• Association for the assistance of medicines accident victims (AAAM), 26 May 2011