1. Clinical Overview
Moxifloxacin is a broad-spectrum fourth-generation fluoroquinolone antibiotic. It is a bactericidal agent that inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, enzymes essential for DNA replication, transcription, repair, and recombination. It is particularly effective against Gram-positive, Gram-negative, and atypical respiratory pathogens. In India, it is a critical agent for managing community-acquired pneumonia, acute bacterial sinusitis, and other infections, but its use is restricted due to concerns about fluoroquinolone-associated adverse effects.
| Onset | Duration | Bioavailability |
|---|---|---|
| Systemic absorption is rapid, with peak plasma concentrations (Cmax) achieved in approximately 1-3 hours. | The pharmacodynamic activity is concentration-dependent and exhibits a post-antibiotic effect. The dosing interval is 24 hours. | Approximately 90% following oral administration. |
2. Mechanism of Action
Moxifloxacin is a bactericidal antibiotic. Its primary mechanism involves inhibition of two essential bacterial type II topoisomerase enzymes: DNA gyrase (primarily in Gram-negative bacteria) and topoisomerase IV (primarily in Gram-positive bacteria).
3. Indications & Uses
- Acute Bacterial Sinusitis (caused by Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis)
- Acute Bacterial Exacerbation of Chronic Bronchitis (caused by S. pneumoniae, H. influenzae, H. parainfluenzae, Klebsiella pneumoniae, Staphylococcus aureus, M. catarrhalis)
- Community-Acquired Pneumonia (caused by S. pneumoniae, H. influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, M. catarrhalis, S. aureus, Legionella pneumophila, K. pneumoniae)
- Uncomplicated Skin and Skin Structure Infections (caused by S. aureus, Streptococcus pyogenes)
4. Dosage & Administration
Adult Dosage: 400 mg orally or intravenously once every 24 hours. Duration: Acute Bacterial Sinusitis: 10 days; Acute Bacterial Exacerbation of Chronic Bronchitis: 5 days; Community-Acquired Pneumonia: 7-14 days; Skin Infections: 7 days.
Administration: Oral tablet can be taken with or without food. Swallow whole with a full glass of water. Do not crush or chew. Maintain adequate hydration. 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.
5. Side Effects
Common side effects may include:
- Nausea
- Diarrhea
- Dizziness
- Headache
- Abdominal pain
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Antacids (Aluminum, Magnesium), Sucralfate, Multivitamins with Zinc/Iron | Markedly reduced absorption of moxifloxacin due to chelation. Plasma levels may become subtherapeutic. | Major |
| Other QT-prolonging drugs (e.g., Class IA/III antiarrhythmics, Erythromycin, Antipsychotics, Tricyclic Antidepressants) | Additive effect on QT prolongation, increasing risk of life-threatening arrhythmias like Torsades de Pointes. | Major |
| Corticosteroids (e.g., Prednisolone) | Increased risk of tendon rupture, especially in elderly. | Major |
| Oral Anticoagulants (Warfarin) | May enhance anticoagulant effect; monitor INR closely. | Moderate |
| Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) | May increase the risk of CNS stimulation and seizures. | Moderate |
| Anti-diabetic agents (Insulin, Sulfonylureas like Glimepiride) | May potentiate hypoglycemic effect, leading to severe hypoglycemia. | Major |
| Theophylline | Limited interaction with moxifloxacin, but monitor for theophylline toxicity as a class precaution. | Moderate |
7. Patient Counselling
- DO take the tablet at the same time each day, with a full glass of water.
- DO complete the full course of therapy, even if you feel better.
- DO maintain adequate fluid intake.
- DO inform your doctor immediately if you experience pain, swelling, or inflammation in a tendon, or if you hear/feel a snap or pop in a joint.
- DO NOT take antacids, multivitamins, or mineral supplements containing magnesium, aluminum, iron, or zinc within 4 hours before or 2 hours after taking moxifloxacin.
- DO NOT crush or chew the tablet.
- DO NOT share your medication with others.
8. Toxicology & Storage
Overdose: Expected symptoms would be an exaggeration of known adverse effects: severe nausea, vomiting, diarrhea, dizziness, seizures, QT prolongation. Crystalluria with renal toxicity is less likely than with older quinolones.
Storage: Store below 30°C. Protect from light and moisture. Keep in the original blister pack or container. Keep out of reach of children. Do not use after the expiry date printed on the pack.