Medically reviewed on May 28, 2018
What are Quinolones?
Quinolones are a type of antibiotic. Antibiotics kill or inhibit the growth of bacteria.
There are five different quinolone classes. In addition, another class of antibiotic, called fluoroquinolones, were derived from quinolones by modifying their structure with fluorine. Quinolones and fluoroquinolones have many things in common, but also a few differences such as what organisms they are effective against. Some people use the words quinolones and fluoroquinolones interchangeably.
Quinolones and fluoroquinolones detrimentally affect the function of two enzymes produced by bacteria, topoisomerase IV and DNA gyrase, so that they can no longer repair DNA or help in its manufacture.
What are quinolones and fluoroquinolones used for?
Quinolones and fluoroquinolones are considered broad-spectrum antibiotics. This means that they are effective against a wide range of bacteria.
However, because of their risk of serious side effects, the FDA has advised that they should only be used to treat conditions such as sinusitis, bronchitis, and uncomplicated urinary tract infections when other, less toxic antibiotics are not appropriate.
Quinolones and fluoroquinolones may also be used to treat unusual infections such as anthrax or plague. Doctors may also decide to use them for other types of infection when other alternative treatment options have failed or cannot be used.
What are the differences between quinolones and fluoroquinolones?
Quinolones and fluoroquinolones differ in their activity against the two enzymes produced by bacteria, topoisomerase IV and DNA gyrase. Those that are more active against topoisomerase IV have more of an effect against gram-positive bacteria, those that are active against DNA gyrase, are more active against gram-negative bacteria. Newer fluoroquinolones tend to target these enzymes equally.
Quinolones and fluoroquinolones also differ in the way they are absorbed, metabolized and excreted in the body.
Table: List of common quinolones and fluoroquinolones
|Generic name||Brand name examples|
|cinoxacin||Discontinued in the U.S.|
|ciprofloxacin||Cipro, Proquin XR|
|nalidixic acid||Discontinued in the U.S.|
|norfloxacin||Discontinued in the U.S.|
|sparfloxacin||Discontinued in the U.S.|
Are quinolones and fluoroquinolones safe?
Quinolones and fluoroquinolones should be avoided in children under the age of 18 years unless they have a serious infection that cannot be treated with any other antibiotic. This is because they can damage the weight-bearing joints in children, and children are also more susceptible to other adverse effects of quinolones and fluoroquinolones, including tendinitis and tendon rupture.
Quinolones and fluoroquinolones are considered safe when taken by adults for short periods of time and exactly as directed by a doctor. However, they have been associated with some serious effects, including tendinitis (inflammation of a tendon) and tendon rupture. In addition, some people have reported peripheral neuropathy (nerve pain in the fingers and toes) and central nervous system effects such as psychosis, convulsions, and hallucinations while taking quinolones or fluoroquinolones.
The risk of tendinitis and tendon rupture is increased in people over the age of 60, in those taking corticosteroids, or with a history of organ transplant. Previous tendon disorders or strenuous activity may also increase risk.
Occasionally, liver damage and allergic reactions have occurred in people taking quinolones or fluoroquinolones.
If any of these very severe side effects happen, the quinolone or fluoroquinolone should be discontinued immediately, and all other quinolones and fluoroquinolones avoided in the future.
What are the side effects of quinolones and fluoroquinolones?
Quinolones and fluoroquinolones may also cause anxiety, insomnia, psychotic reactions, nerve pain or a loss of feeling in the extremities, electrocardiogram (ECG) abnormalities, increased sensitivity to light and other effects.
In people with diabetes, quinolones and fluoroquinolones may affect blood glucose levels requiring extra monitoring.
Quinolones and fluoroquinolones increase the sensitivity of the skin to the sun and may cause photo-sensitivity reactions and severe sunburn on exposed areas of skin.
Quinolones and fluoroquinolones are not suitable for people with myasthenia gravis, certain heart rhythm disturbances, or children and adolescents under the age of 18 (unless the infection cannot be treated by another antibiotic).
List of Quinolones:
Medical conditions associated with quinolones:
- Anthrax Prophylaxis
- Bacterial Infection
- Bladder Infection
- Bone infection
- Campylobacter Gastroenteritis
- Chlamydia Infection
- Crohn's Disease, Acute
- Cutaneous Bacillus anthracis
- Epididymitis, Non-Specific
- Epididymitis, Sexually Transmitted
- Febrile Neutropenia
- Gonococcal Infection, Disseminated
- Gonococcal Infection, Uncomplicated
- Granuloma Inguinale
- Infection Prophylaxis
- Infectious Diarrhea
- Intraabdominal Infection
- Joint Infection
- Kidney Infections
- Leprosy, Borderline
- Leprosy, Lepromatous
- Meningococcal Meningitis Prophylaxis
- Methicillin-Resistant Staphylococcus Aureus Infection
- Mycobacterium avium-intracellulare, Treatment
- Nongonococcal Urethritis
- Nosocomial Pneumonia
- Otitis Media
- Pelvic Infections
- Pelvic Inflammatory Disease
- Plague Prophylaxis
- Pneumonia with Cystic Fibrosis
- Prevention of Bladder infection
- Rabbit Fever
- Salmonella Enteric Fever
- Salmonella Gastroenteritis
- Skin and Structure Infection
- Skin or Soft Tissue Infection
- Strep Throat
- Streptococcal Infection
- Surgical Prophylaxis
- Transurethral Prostatectomy
- Traveler's Diarrhea
- Tuberculosis, Active
- Typhoid Fever
- Urinary Tract Infection