API 7-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid

Fluoroquinolonic acid More Info

Fluoroquinolonic acid （ , also known as quinolone carboxylic acids, is a class of synthetic broad - spectrum antibacterial agents.

1. Chemical structure and characteristics

The basic structure of fluoroquinolones contains a quinolone nucleus with a carboxylic acid group at the 3 - position and a fluorine atom attached to the molecule. The presence of the fluorine atom significantly enhances the antibacterial activity and pharmacokinetic properties of these drugs. This unique chemical structure allows them to interact with bacterial DNA gyrase and topoisomerase IV, which are essential enzymes for bacterial DNA replication, transcription, and repair.

2. Mechanism of action

Fluoroquinolones exert their antibacterial effect by inhibiting the activity of bacterial DNA gyrase (in gram - negative bacteria) and topoisomerase IV (in gram - positive bacteria). DNA gyrase and topoisomerase IV are responsible for maintaining the supercoiled structure of bacterial DNA. When these enzymes are inhibited, the DNA replication process is disrupted, leading to the formation of abnormal DNA structures and ultimately cell death.

For example, in Escherichia coli (a gram - negative bacterium), the drug binds to the DNA - gyrase - DNA complex and stabilizes a covalent intermediate formed during the breakage - reunion reaction of DNA strands. This stabilization prevents the resealing of the DNA strands, causing double - strand breaks and inhibiting DNA replication.

3. Spectrum of antibacterial activity

Fluoroquinolones have a broad antibacterial spectrum, covering both gram - negative and gram - positive bacteria. They are effective against many common pathogens such as Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa (gram - negative bacteria), and Staphylococcus aureus, Streptococcus pneumoniae (gram - positive bacteria).

However, the increasing use of fluoroquinolones has led to the emergence of resistant strains. Some bacteria have developed mutations in the target enzymes (DNA gyrase and topoisomerase IV) or acquired efflux pumps that can expel the drug from the cell, reducing the drug's efficacy.

4. Pharmacokinetics

These drugs are generally well - absorbed after oral administration, with good bioavailability. They are distributed widely throughout the body, including in tissues and body fluids such as the lungs, kidneys, prostate, and cerebrospinal fluid (in some cases with appropriate penetration).

The elimination half - life of different fluoroquinolones varies, but generally, they are excreted mainly through the kidneys, either as unchanged drug or as metabolites.

5. Clinical uses

Fluoroquinolones are used to treat a wide range of infections. They are commonly used for urinary tract infections, respiratory tract infections (such as bronchitis and pneumonia), skin and soft - tissue infections, and gastrointestinal infections caused by susceptible bacteria.

In some cases, they are also used in the prophylaxis of infections, for example, in patients at high risk of neutropenic fever due to chemotherapy.

6. Side effects

The most common side effects include gastrointestinal disturbances such as nausea, vomiting, diarrhea, and abdominal pain. Central nervous system side effects can also occur, such as headache, dizziness, insomnia, and in rare cases, seizures, especially in patients with a history of epilepsy or other predisposing factors.

There may also be some less common side effects like tendonitis and tendon rupture, especially in elderly patients and those taking corticosteroids simultaneously.