Moxifloxacin is a broad-spectrum, fourth-generation fluoroquinolone antibiotic. It is bactericidal and acts by inhibiting bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, enzymes essential for DNA replication, transcription, repair, and recombination. It is particularly noted for its enhanced activity against Gram-positive bacteria, atypical pathogens, and anaerobes compared to earlier fluoroquinolones, while maintaining good Gram-negative coverage. In India, it is a critical agent for managing community-acquired respiratory and intra-abdominal infections, especially where resistance to first-line agents is suspected.
Adult: 400 mg orally or intravenously once every 24 hours. Duration: Sinusitis/Bronchitis: 5-10 days; Pneumonia: 7-14 days; Skin infections: 7 days; Intra-abdominal infections: 5-14 days.
Note: Tablet: Can be taken with or without food. Swallow whole with a full glass of water. Do not crush or chew. IV Infusion: 400 mg in 250 mL of compatible solution (e.g., 0.9% Sodium Chloride, 5% Dextrose) infused over 60 minutes. Avoid rapid infusion. Do not administer as IV bolus.
Moxifloxacin is a bactericidal antibiotic. Its primary mechanism involves inhibition of two essential bacterial type II topoisomerase enzymes: DNA gyrase and topoisomerase IV. DNA gyrase (primarily in Gram-negative bacteria) is responsible for introducing negative supercoils into DNA, essential for replication and transcription. Topoisomerase IV (primarily in Gram-positive bacteria) is crucial for separating interlinked daughter chromosomes after DNA replication. By binding to the enzyme-DNA complex, moxifloxacin stabilizes it and prevents the religation of DNA strands, leading to double-strand breaks, inhibition of DNA synthesis, and ultimately bacterial cell death.
Pregnancy: Pregnancy Category C (US FDA). Animal studies have shown fetal arthropathy and other abnormalities. There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus. Generally avoided, especially in first trimester.
Driving: May cause dizziness, lightheadedness, or visual disturbances. Patients should be cautioned about operating machinery or driving until they are certain the medication does not affect them adversely.
| Antacids (Al, Mg), Sucralfate, Multivitamins with Zinc/Iron | Markedly reduced absorption of moxifloxacin due to chelation. Decreased efficacy. | Major |
| Warfarin | May enhance anticoagulant effect, increasing INR and risk of bleeding. Monitor INR closely. | Major |
| Anti-diabetic drugs (Insulin, Sulfonylureas) | May potentiate hypoglycemic or hyperglycemic effects. Monitor blood glucose. | Major |
| QT-prolonging drugs (Class Ia/III antiarrhythmics, Erythromycin, Clarithromycin, Antipsychotics, TCAs) | Additive risk of QT prolongation and cardiac arrhythmias (torsades de pointes). | Contraindicated/Major |
| NSAIDs (e.g., Ibuprofen) | May increase the risk of CNS stimulation and seizures. | Moderate |
| Corticosteroids (e.g., Prednisolone) | Increased risk of tendon rupture, especially in elderly. | Major |
| Probenecid | Minimal interaction as renal excretion is a minor pathway for moxifloxacin. | Minor |