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Pharmacology · Fluoroquinolones

Moxifloxacin !

A respiratory fluoroquinolone with anaerobic activity, cleared mostly by the liver. A WHO medicine for drug-resistant tuberculosis.

Updated 2026-11-01

  • Class: Fluoroquinolones
  • Enzyme: Bacterial DNA gyrase and topoisomerase IV
  • ATC code: J01MA14
  • WHO Model List of Essential Medicines

The figure shows moxifloxacin bound to DNA cut by Staphylococcus aureus DNA gyrase.

Target in 3D: Bacterial DNA gyrase and topoisomerase IV. PDB structure 5CDQ (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Moxifloxacin traps DNA gyrase and topoisomerase IV on cleaved DNA, turning them into lethal double-strand breaks. Its 8-methoxy group strengthens activity against gram-positive bacteria and anaerobes, but it is weak against Pseudomonas.

  1. Absorbed by mouth or given IV
  2. Binds gyrase and topoisomerase IV on cut DNA
  3. The DNA cannot be resealed
  4. Double-strand breaks kill the bacterium

Pharmacokinetics

Absorption
Oral bioavailability about 90%.
Metabolism
Liver, by glucuronide and sulfate conjugation; cytochrome P450 is not involved.
Elimination
Urine and faeces; no dose change in kidney failure.
Half-life
About 12 hours.

Indications

Adverse effects

Common

  • Nausea, diarrhoea and dizziness
  • Headache
  • Photosensitivity

Contraindications

  • Allergy to moxifloxacin or other quinolones

Key interactions

Antacids, iron, zinc, sucralfate
Reduce absorption; doses are spaced.
Antiarrhythmics and other QT-prolonging drugs
Additive QT risk; avoided.
Warfarin
Stronger anticoagulant effect.

What is monitored

  • ECG and potassium/magnesium if there is QT risk
  • Blood glucose in diabetes
  • Tendon and nerve symptoms

Administration and safety

  • The IV form is infused slowly, not as a bolus
  • Oral doses are spaced from minerals

Nursing care

  • Ask about heart rhythm problems and QT drugs
  • Teach to report palpitations, fainting, tendon pain or tingling
  • Check glucose in diabetes

Pregnancy and breastfeeding

No malformations in animal studies at clinical exposures; usually avoided when safer drugs exist.

Test yourself

Think of the answer, then tap the question to see it.

Does moxifloxacin need a dose change in kidney failure?

No; it is not mainly cleared by the kidney.

Which important gram-negative does moxifloxacin cover poorly?

Pseudomonas aeruginosa.

Which mycobacterial use does moxifloxacin have?

Treatment of drug-resistant tuberculosis.

Add to my cards (3)

← Back to the class: Fluoroquinolones

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - MOXIFLOXACIN HYDROCHLORIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); Moxifloxacin: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); 2.95A structure of Moxifloxacin with S.aureus DNA gyrase and DNA (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.