Moxifloxacin: Clinical Use and Dosing
Standard Dosing and Administration
Moxifloxacin is administered as 400 mg orally once daily, with treatment duration varying from 5-21 days depending on the specific infection being treated. 1
Community-acquired pneumonia: 400 mg once daily for 7-14 days 1
Complicated intra-abdominal infections: 400 mg once daily for 5-14 days 1
Acute bacterial sinusitis: 400 mg once daily for 10 days 1
Acute bacterial exacerbation of chronic bronchitis: 400 mg once daily for 5 days 1
Uncomplicated skin and skin structure infections: 400 mg once daily for 7 days 1
Complicated skin and skin structure infections: 400 mg once daily for 7-21 days 1
Moxifloxacin can be taken with or without food, and patients should drink fluids liberally 1
When switching from intravenous to oral formulation, no dosage adjustment is necessary 1
No dosage adjustment is required for patients with renal or hepatic impairment 2, 3
Complicated Intra-Abdominal Infections
Moxifloxacin is approved as single-agent therapy for mild-to-moderate community-acquired complicated intra-abdominal infections, achieving clinical cure rates of 89-90%. 4
- Moxifloxacin demonstrated non-inferiority to ertapenem for complicated intra-abdominal infections, with cure rates of 89.5% versus 93.4% 4
- For localized peritonitis, moxifloxacin achieved a 93.0% response rate 4
- For cholecystitis, moxifloxacin achieved a 100% response rate 4
Critical Limitations for Intra-Abdominal Infections
- Avoid moxifloxacin if the patient has received quinolone therapy within 3 months, as organisms are likely to be quinolone-resistant 4
- Quinolones should not be used unless hospital surveys indicate ≥90% susceptibility of E. coli to quinolones 4
- Moxifloxacin should not be used for higher-severity community-acquired infection or health care-associated infection, as such regimens may carry greater risk of toxicity and facilitate acquisition of more-resistant organisms 4
Respiratory Tract Infections
Moxifloxacin provides comprehensive coverage for all major respiratory tract pathogens, including penicillin- and macrolide-resistant Streptococcus pneumoniae, with clinical success rates exceeding 90%. 2, 5
- Moxifloxacin has excellent activity against pneumococci, including penicillin- and macrolide-resistant strains, with MIC90 <0.25 mg/L 2, 3
- Coverage includes Haemophilus species, Moraxella catarrhalis, and atypical pathogens (Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila) with MIC90 <1.0 mg/L 3
- Moxifloxacin achieves high penetration into respiratory tissues and fluids 2, 6, 3
Acute Bacterial Sinusitis
- For moderate severity sinusitis in adults who have received antibiotics in the previous 4-6 weeks, respiratory fluoroquinolones (including moxifloxacin) are recommended as initial therapy 4
- Moxifloxacin is an alternative to high-dose amoxicillin/clavulanate for adults with moderate disease 4
Antimicrobial Spectrum and Resistance
Moxifloxacin demonstrates broad-spectrum activity against aerobic and anaerobic bacteria, with lower propensity for resistance development compared to older fluoroquinolones. 2, 6
- More than 87% of baseline anaerobic isolates from intra-abdominal infections were susceptible to moxifloxacin (MIC ≤2 mg/mL) 4
- Clinical success rate for anaerobes remained >80% even for isolates with MICs of 4-16 mg/mL 4
- Emergence of bacterial resistance was less common with moxifloxacin than with some other fluoroquinolones in in vitro studies 2
Pharmacokinetic Advantages
- Mean Cmax after single 400 mg oral dose: 3.2 mg/L; at steady-state: 4.5 mg/L 3
- Terminal elimination half-life: 12.0 hours, allowing once-daily dosing 3
- Balanced system of excretion eliminates need for dosage adjustments in renal or hepatic impairment 3
- Metabolism does not involve cytochrome P450 system, minimizing drug interactions 3
Critical Drug Interactions
Administer moxifloxacin at least 4 hours before or 8 hours after products containing multivalent cations (magnesium, aluminum, iron, zinc), including antacids, sucralfate, multivitamins, and didanosine buffered tablets. 1
Serious Adverse Reactions and Contraindications
Moxifloxacin carries FDA black box warnings for disabling and potentially irreversible serious adverse reactions, including tendinitis and tendon rupture, peripheral neuropathy, and central nervous system effects. 1
- QTc prolongation occurs in some patients; clinical significance in high-risk patients requires careful consideration 2, 7
- Exacerbation of myasthenia gravis is contraindicated 1
- Risk of Clostridium difficile-associated diarrhea 1
- Hypersensitivity reactions and photosensitivity/phototoxicity can occur 1
- Blood glucose disturbances may occur, particularly in diabetic patients 1
Safety Profile
- Overall incidence rates of adverse events were similar between moxifloxacin and comparators in 14 years of clinical data involving 30,004 patients 7
- Most commonly reported adverse events are gastrointestinal disturbances 2, 7
- Moxifloxacin has low propensity for phototoxic reactions relative to other fluoroquinolones 2
- Incidence rates of hepatic disorders, tendon disorders, serious cutaneous reactions, and C. difficile-associated diarrhea were similar to comparators 7
Appropriate Patient Selection
Reserve moxifloxacin for patients with community-acquired infections who have not received quinolones within 3 months and where local resistance patterns support its use. 4
- Moxifloxacin is appropriate first-line therapy for community-acquired complicated intra-abdominal infections in regions with low frequencies of ESBL-producing isolates 4
- For respiratory infections, moxifloxacin is particularly valuable in areas where drug-resistant S. pneumoniae or H. influenzae are common 2
- The WHO Essential Medicines List classifies fluoroquinolones in the "Watch" group, indicating their use should be monitored to prevent resistance 4