Quinolones for Cystic Fibrosis

Quinolones are synthetic broad-spectrum antibacterial agents. They kill bacteria by stopping an important enzyme needed for their replication.1 Quinolones, which include the antibiotics ciprofloxacin and levofloxacin, are FDA-approved to treat conditions such as lower respiratory tract infections, skin infections, and urinary tract infections — all of which are common in people with cystic fibrosis (CF).2

History of quinolones

Quinolones were discovered more than 50 years ago, synthesized by scientists in the lab. In 1962, Dr. George Lesher and his team accidentally discovered nalidixic acid as a secondary product of the synthesis of the antimalarial drug chloroquine. The accident led to the development of next-generation quinolone drugs, some of which are still used today. Ciprofloxacin is part of the second generation of quinolones and levofloxacin the third generation, with ciprofloxacin a potent agent against Pseudomonas aeruginosa.Pseudomonas infections, however, are becoming more difficult to treat because of increasing antibiotic resistance.

How quinolones work

Quinolones have broad spectrum activity, making them effective against gram-positive and gram-negative bacteria. They kill bacteria by stopping the bacterial DNA gyrase enzyme, which is needed for DNA replication. Since a copy of DNA must be made each time a cell divides, if an antibiotic interferes with replication, it makes it more difficult for bacteria to multiply.4

Other details about quinolones

Ciprofloxacin or levofloxacin come in tablet form, and each can also be injected. Some of their common side effects are nausea, vomiting, diarrhea, stomach pain, constipation, heartburn, vaginal itching and/or discharge, pale skin and unusual tiredness.5,6

There are important warnings with quinolones. Taking ciprofloxacin or levofloxacin may increase the risk of developing tendinitis or having a tendon rupture even several months after finishing the treatment. The treatment also may lead to changes in sensation and nerve damage that may not go away even after the treatment is finished. Quinolones may also cause serious brain and nervous-system side effects, even after the first dose. People with muscle disorders may feel a worsening of symptoms.5,6


Cystic Fibrosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider for questions you may have about a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.


  1. https://www.drugs.com/drug-class/quinolones.html
  2. https://www.cff.org/Living-with-CF/Treatments-and-Therapies/Medications/Antibiotics/
  3. http://cid.oxfordjournals.org/content/41/Supplement_2/S113.long
  4. http://www.scienceprofonline.com/microbiology/mode-of-action-of-quinolone-antibiotics.html
  5. https://medlineplus.gov/druginfo/meds/a697040.html
  6. https://medlineplus.gov/druginfo/meds/a688016.html