BLACK BOX WARNING
- tendinitis and tendon rupture
- peripheral neuropathy
- CNS effects
- exacerbation of myasthenia gravis
- aortic aneurysm
moxifloxacin
Brand: Avelox
⚠ BBW Prototype: ciprofloxacin
Drug Class: fluoroquinolone antibiotic
Drug Family: antibiotic
Subclass: respiratory fluoroquinolone with enhanced anaerobic activity
Organ Systems: infectious-diseaserespiratory
Mechanism of Action
Inhibits DNA gyrase and topoisomerase IV; has greater gram-positive and anaerobic activity than ciprofloxacin or levofloxacin, but lacks anti-pseudomonal activity. Renal clearance is not the primary elimination route — no dose adjustment in CKD.
DNA gyrase (topoisomerase II)topoisomerase IV
Indications
- community-acquired pneumonia (including atypical pathogens)
- acute bacterial sinusitis
- acute exacerbation of chronic bronchitis
- complicated skin/soft tissue infections
- intra-abdominal infections (with anaerobic coverage)
- tuberculosis (second-line)
Contraindications
- fluoroquinolone hypersensitivity
- QTc prolongation
- uncorrected hypokalemia
- hepatic impairment (relative)
Adverse Effects
Common
- nausea
- diarrhea
- headache
Serious
- QTc prolongation (greatest among fluoroquinolones)
- torsades de pointes
- tendinopathy/rupture
- C. difficile colitis
- hepatotoxicity
- peripheral neuropathy
Pharmacokinetics (ADME)
| Absorption | 90% oral bioavailability; food has minimal effect |
| Distribution | large Vd; excellent tissue concentrations |
| Metabolism | hepatic glucuronide and sulfate conjugation (not CYP); no dose adjustment for renal disease |
| Excretion | fecal (38%) and renal (20% unchanged) |
| Half-life | 12 hours |
| Onset | rapid |
| Peak | 0.5–4 hours (oral) |
| Duration | 24 hours (once-daily) |
| Protein Binding | 45–50% |
| Vd | large (2–3 L/kg) |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| QTc-prolonging drugs (antiarrhythmics, antipsychotics) | additive QTc prolongation; highest risk among fluoroquinolones | major |
| antacids/iron/sucralfate | chelation reduces moxifloxacin absorption; separate by 2 hours | moderate |
Nursing Considerations
- Moxifloxacin carries the greatest QTc-prolonging risk among fluoroquinolones; obtain ECG and review all concurrent medications before use.
- No renal dose adjustment needed — an advantage in patients with CKD compared to levofloxacin.
- Monitor for hepatotoxicity with prolonged use or in patients with baseline liver disease.
- Adhere to all fluoroquinolone class black box warning counseling points: tendon effects, peripheral neuropathy, CNS effects, myasthenia gravis exacerbation.
Clinical Pearls
- Moxifloxacin is the only fluoroquinolone with meaningful anaerobic coverage (active against Bacteroides fragilis), enabling it to be used as monotherapy for intra-abdominal infections.
- No renal dose adjustment is required because moxifloxacin is primarily eliminated via hepatic glucuronidation and fecal excretion rather than renal filtration.
Safety Profile
Pregnancy avoid
Lactation avoid
Renal Adjustment Not required
Hepatic Adjustment Required
TDM Not required
Guideline Update pending
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.