Moxifloxacin, a fourth-generation fluoroquinolone, exerts its bactericidal effect by inhibiting two critical bacterial enzymes: DNA gyrase (topoisomerase II) and topoisomerase IV. These enzymes are essential for DNA replication, transcription, repair, and chromosome segregation. By binding to these enzymes, moxifloxacin induces double-stranded DNA breaks, leading to rapid bacterial cell death.

Moxifloxacin has broad-spectrum activity against:

• Gram-positive bacteria: Streptococcus pneumoniae, Staphylococcus aureus (methicillin-susceptible).
• Gram-negative bacteria: Haemophilus influenzae, Moraxella catarrhalis, Escherichia coli.
• Atypical pathogens: Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila.
• Anaerobic bacteria: Bacteroides fragilis.

Moxifloxacin is indicated for:

1. Respiratory Tract Infections:
   • Community-acquired pneumonia (CAP).
   • Acute bacterial sinusitis.
   • Acute exacerbations of chronic bronchitis (AECB).
2. Skin and Soft Tissue Infections:
   • Uncomplicated cellulitis.
3. Intra-Abdominal Infections:
   • Complicated infections (in combination with other agents).
4. Ophthalmic Infections:
   • Bacterial conjunctivitis (0.5% ophthalmic solution).

Off-label uses include tuberculosis (as part of multidrug regimens) and pelvic inflammatory disease.

Adults:

• Oral/IV: 400 mg once daily.
  • Duration: 5–14 days, depending on infection severity.
• Ophthalmic: 1 drop to affected eye(s) 3 times daily for 7 days.

Special Populations:

• Renal Impairment: No dose adjustment required (primarily hepatic metabolism).
• Hepatic Impairment: Use with caution; avoid in severe cirrhosis (BNF).
• Elderly: Monitor for tendonitis and CNS effects.

• Common: Nausea, diarrhea, dizziness, headache.
• Serious:
  • QT Prolongation: Risk of torsades de pointes (avoid in patients with baseline QT >450 ms).
  • Tendon Rupture: Risk increases with age >60, corticosteroid use, or renal failure.
  • Hepatotoxicity: Elevated transaminases (monitor LFTs).
  • CNS Effects: Insomnia, hallucinations, seizures (rare).
  • Hypersensitivity: Rash, anaphylaxis.

1. Contraindications:
   • History of tendon disorders or QT prolongation.
   • Myasthenia gravis (may exacerbate muscle weakness).
2. Pregnancy/Lactation:
   • Category C: Avoid unless benefits outweigh risks (teratogenic in animal studies).
   • Excreted in breast milk; discontinue breastfeeding.
3. Hepatic/Renal Monitoring:
   • Monitor LFTs in liver disease; assess renal function in elderly.
4. Photosensitivity: Advise sun protection.

Moxifloxacin interacts with:

• QT-Prolonging Drugs:
  • Antiarrhythmics (e.g., amiodarone), antipsychotics (e.g., haloperidol) – additive risk of arrhythmias.
• Antacids/Minerals:
  • Aluminum, magnesium, or iron supplements reduce absorption (administer 2–4 hours apart).
• Corticosteroids:
  • Increased risk of tendon rupture.
• Warfarin:
  • Enhanced anticoagulant effect (monitor INR).

• Generic: Moxifloxacin (oral, IV, ophthalmic).
• Brand Names: Avelox (oral/IV), Vigamox (ophthalmic).