Fluoroquinolones antibiotic is any member of a large group of broad-spectrum bactericides that share a bicyclic core structure related to the compound 4-quinolone.They are used in human and veterinary medicine to treat bacterial infections, as well as in animal husbandry.Nearly all quinolone antibiotics in use are fluoroquinolones, which contain a fluorine atom in their chemical structure and are effective against both Gram-negative and Gram-positive bacteria. One example is ciprofloxacin, one of the most widely used antibiotics worldwide.
Types of Fluoroquinolones antibiotic
Quinolones can be classified into generations based on their antibacterial spectrum. The earlier-generation agents are, in general, more narrow-spectrum than the later ones, but there is no standard employed to determine which drug belongs to which generation. The only universal standard applied is the grouping of the non-fluorinated drugs found within this class (quinolones) within the first-generation heading. As such, there exists a wide variation within the literature dependent upon the methods employed by the authors.
The first generation is rarely used. Frequently prescribed drugs are Avelox (moxifloxacin), Cipro (ciprofloxacin), Levaquin (levofloxacin), and, to some extent, their generic equivalents.
First generation
- flumequine
- oxolinic acid
- rosoxacin
Structurally related first generation drugs, but formally not 4-quinolones, include cinoxacin ,nalidixic acid and piromidic acid(Panacid), pipemidic acid
Second generation
The second-generation class is sometimes subdivided into “Class 1” and “Class 2”.
- ciprofloxacin
- fleroxacin
- lomefloxacin
- nadifloxacin
- norfloxacin
- ofloxacin
- pefloxacin
- rufloxacin
A structurally related second generation drug, but formally not a 4-quinolone, is enoxacin
Third generation
Unlike the first and second generations, the third generation is active against streptococci.
- balofloxacin
- grepafloxacin
- levofloxacin
- pazufloxacin
- sparfloxacin
- temafloxacin
A structurally related third generation drug, but formally not a 4-quinolone, is tosufloxacin
Fourth generation
Fourth-generation fluoroquinolones act at DNA gyrase and topoisomerase IV. This dual action slows development of resistance.
- clinafloxacin
- gatifloxacin
- moxifloxacin
- sitafloxacin
- prulifloxacin
- besifloxacin
Two structurally related third generation drugs, but formally not 4-quinolones, are gemifloxacin (Factive) and trovafloxacin (Trovan) (removed from clinical use).
In development.
- delafloxacin
- ozenoxacin
FDA Officials Update Fluoroquinolone Warning
Officials with the FDA have updated a previous safety announcement that notes that “findings from published studies currently do not support reports that these medicines may result in detachment of the retina in the eyes, or bulges or tears in the aorta blood vessel called aortic aneurysm and aortic dissection.”
The FDA issued the drug communication this week as an update to a drug safety communication issued in May, 2016 that warned about the potential for these complications from these medications.
That communication noted that systemic use of fluoroquinolones is associated with “disabling and potentially permanent serious side effects that can occur together” involving the tendons, muscles, joints, nerves, and central nervous system, such as a torn Achilles tendon. It followed an advisory committee to review the risk-benefit balance for fluoroquinolones. The committee determined that the risk wasn’t worth the potential benefit for patients with sinusitis, bronchitis, and uncomplicated urinary tract infections, for which other treatment options exist.
Labels and medication guides for all fluoroquinolones were updated to reflect the FDA’s findings, and that update included the wording on the retina problems.
In the most recent safety communication, FDA officials noted: “We will continue to assess safety issues with fluoroquinolones and will update the public if additional actions are needed.”
Reference FDA Drug Safety Communication: FDA updates warnings for oral and injectable fluoroquinolone antibiotics due to disabling side effects. Gaithersburg, MD. FDA website. https://www.fda.gov/Drugs/DrugSafety/ucm511530.htm? Accessed May 10, 2017.
Mechanism of action
Quinolones exert their antibacterial effect by preventing bacterial DNA from unwinding and duplicating. The majority of quinolones in clinical use are fluoroquinolones, which have a fluorine atom attached to the central ring system, typically at the 6-position or C-7 position. Most of them are named with the -oxacin suffix.
Quinolones and fluoroquinolones are chemotherapeutic bactericidal drugs, eradicating bacteria by interfering with DNA replication. Quinolones inhibit the bacterial DNA gyrase or the topoisomerase IV enzyme, thereby inhibiting DNA replication and transcription. Topoisomerase II is also a target for a variety of quinolone-based drugs. High activity against the eukaryotic type II enzyme is exhibited by drugs containing aromatic substituents at their C-7 positions. First and second generation fluoroquinolones selectively inhibit the topoisomerase II ligase domain, leaving the two nuclease domains intact. This modification, coupled with the constant action of the topoisomerase II in the bacterial cell, leads to DNA fragmentation via the nucleasic activity of the intact enzyme domains. Third and fourth generation fluoroquinolones are more selective for the topoisomerase IV ligase domain, and thus have enhanced gram-positive coverage.
Indications of Fluoroquinolones antibiotic
Fluoroquinolones are often used for genitourinary infections and are widely used in the treatment of hospital-acquired infections associated with urinary catheters. In community-acquired infections, they are recommended only when risk factors for multidrug resistance are present or after other antibiotic regimens have failed. However, for serious acute cases of pyelonephritis or bacterial prostatitis where the person may need to be hospitalised, fluoroquinolones are recommended as first-line therapy.
Due to people with the sickle-cell disease being at increased risk for developing osteomyelitis from the Salmonella, fluoroquinolones are the “drugs of choice” due to their ability to enter bone tissue without chelating it, as tetracyclines are known to do.
Fluoroquinolones are featured prominently in guidelines for the treatment of hospital-acquired pneumonia.
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