Fluoroquinoline antibiotics

 Fluoroquinolones are a class of broad-spectrum antibiotics widely used to treat a variety of bacterial infections. They work by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes critical for DNA replication, transcription, and repair. This mechanism leads to the death of the bacteria, making fluoroquinolones bactericidal.

Key Characteristics:

1. Broad-Spectrum Activity: Effective against both Gram-negative and Gram-positive bacteria.
2. Examples: Ciprofloxacin, Levofloxacin, Moxifloxacin, and Norfloxacin.
3. Indications: Used to treat urinary tract infections (UTIs), respiratory tract infections, skin infections, and gastrointestinal infections.

Mechanism of Action:

Fluoroquinolones target two essential bacterial enzymes:

• DNA Gyrase (in Gram-negative bacteria): Relieves strain while the DNA is being unwound.
• Topoisomerase IV (in Gram-positive bacteria): Separates replicated DNA, enabling cell division.

Pharmacokinetics:

• Oral and Intravenous Use: These antibiotics are well absorbed from the gastrointestinal tract, and their bioavailability is generally high.
• Good Tissue Penetration: Fluoroquinolones reach therapeutic concentrations in many tissues, making them effective for various types of infections.

Resistance:

Overuse of fluoroquinolones has led to increasing resistance among certain bacterial strains. Resistance mechanisms include mutations in DNA gyrase or topoisomerase IV and efflux pump activation that expels the drug from bacterial cells.

Adverse Effects:

• Gastrointestinal disturbances (nausea, diarrhea)
• Central nervous system effects (dizziness, headache)
• Tendonitis and tendon rupture
• Potential QT prolongation, leading to cardiac issues

Fluoroquinolones are highly effective but must be used judiciously to avoid contributing to antibiotic resistance.