Quinolone

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Fluoroquinolones form a group of broad-spectrum antibiotics. They are related to nalidixic acid.

Fluoroquinolone antibiotics are highly potent and at one time they were considered relatively safe. However, they can have potentially troublesome and irreversable side effects. For example, numerous case reports (since 1965) have implicated their use in cases of spontaneous tendon ruptures and tendon damage, especially with the concurrent use of a systemic corticosteroid. In the fall of 2004 the FDA upgraded the warnings found within the package inserts for all drugs within this class regarding such serious adverse reactions. These new warnings included:

Peripheral neuropathy (irreversible nerve damage): "rare cases of sensory or sensor motor axonal polyneuropathy affecting small and or large axons resulting in paresthesias, hypoaesthesias, dysesthesias, and weakness have been reported in patients taking quinolones. Therapy should be discontinued if the patient experiences symptoms of neuropathy including pain, burning, tingling, numbness and or weakness or is found to have deficits in light touch, pain, temperature, position sense, vibratory sensation, and or motor strength in order to prevent the development of an irreversible condition."

Tendon damage: "Ruptures of the shoulder, hand, Achilles tendon or other tendons that require surgical repair or resulted in prolonged disability have been reported in patients receiving quinolones. Post-marketing surveillance reports indicate that this risk may be increased in patients receiving concomitant corticosteroids, especially the elderly. Fluoroquinolone therapy should be discontinued if the patient experiences pain, inflammation, or rupture of a tendon. Patients should rest and refrain from exercise until diagnosis of tendonitis or tendon rupture had been excluded. Tendon rupture can occur during or after therapy with quinolones."

As well as the following:

Due to the high potency of this class of drugs, it is advised that they should be used sparingly to reduce to spread of resistance. They are NOT to be considered a first line agent but rather a drug of last resort when all other therapy has failed. Jim Hoover, regional manager for state government affairs for the Bayer Corporation for the five northwest States, discussed the second and third generation quinolones. He states that "...Normally the quinolone class of drugs is used in patients who have failed at least one prior therapy. The patients tend to be fairly ill and require relatively acute care that often may be the last step before they are admitted into the hospital. …By the time the physicians get to this classification, they tend to have a good idea of what bacteria is involved, what antibiotic is the most potent for the bacteria and which penetrates that particular body side the best. …These drugs are often the last step before admission into the hospital..." Alaska Pharmacy and Therapeutics Committee March 19, 2004.

Quinolones can enter cells easily and therefore are often used to treat intracellular pathogens such as Legionella pneumophila and Bacillus anthracis.


Ciprofloxacin, unlike the newer generations of fluroquinolones, seems to inhibit GABA and therefore cause seizures in patients with renal insufficiency.

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Mechanism

Quinolones act by inhibiting the bacterial DNA gyrase and/or the topoisomerase IV enzyme. This way they inhibit DNA replication and act bacteriocidically. As such they are to be considered a chemotherapeutic agent as opposed to a true antibiotic as they prevent replication of the bacterial cell by interfering with the genetic replication of the bacterium.

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1st generation

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2nd generation

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3rd generation

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4th generation

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Developmental

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Veterinary use

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External links

no:Quinoloner pl:Chinolony pt:Quinolona sk:Chinolón

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