Broad-spectrum fluoroquinolone
Moxifloxacin is an antibiotic of the fluoroquinolone class, used to treat respiratory infections (community-acquired pneumonia, exacerbations of chronic bronchitis, sinusitis) in adults. It works by preventing bacteria from multiplying. It should only be used on medical prescription; it can cause serious and rare adverse effects such as tendon rupture, nerve damage and heart rhythm changes (QT prolongation).
Also known as: Avalox, Avelox
Combining Moxifloxacin with Chloroquine may prolong the QT interval and increase the risk of ventricular arrhythmias (torsades de pointes).
Chloroquine prolongs the QT interval (torsade de pointes and ventricular arrhythmias reported, with a higher risk with concomitant QT-prolonging drugs — chloroquine label), and moxifloxacin also prolongs the QT, with cases of torsade de pointes; the moxifloxacin label recommends avoiding use in patients with known prolongation, proarrhythmic conditions (clinically significant bradycardia, acute myocardial ischaemia), hypokalaemia, hypomagnesaemia and with drugs that prolong the QT. The combination should be avoided whenever possible; if unavoidable, monitor the ECG and electrolytes and use the shortest antibiotic course possible.
Chloroquine + moxifloxacin: additive risk of QT prolongation. Avoid or monitor the ECG in at-risk patients.
Moxifloxacin prolongs the QT interval and Chloroquine also affects cardiac repolarization; the additive effect increases the risk of serious ventricular arrhythmias.
Monitor the ECG (QT), potassium/magnesium and cardiac symptoms; caution in patients with long QT or heart disease.
Palpitations, syncope or a very prolonged QT require urgent intervention.
Avoid the combination when possible; monitor the ECG and correct electrolyte disturbances in at-risk patients.
DailyMed/FDA (NIH/NLM) — approved Moxifloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1ed191f5-7df5-488c-bb72-91ac0b618d9a ; approved Chloroquine label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=06c69e2b-211b-4746-9f3a-f86d36520570 — with additional reference: Prontuário Terapêutico do INFARMED, INFARMED (11th ed., 2012)
Antacids with cations (aluminium, magnesium, calcium) and iron/zinc preparations significantly reduce Moxifloxacin absorption, compromising its efficacy.
Moxifloxacin, a broad-spectrum fluoroquinolone, forms insoluble chelates with di- and trivalent cations (aluminium, magnesium, calcium) present in antacids, reducing oral bioavailability and risking therapeutic failure in respiratory or pelvic infections. The moxifloxacin label recommends administering the antibiotic 4 hours before or 8 hours after antacids containing magnesium or aluminium, sucralfate, iron or zinc. This wide spacing should be clearly explained to the patient, since moxifloxacin is usually taken once daily.
Antacids + moxifloxacin: cations (Al, Mg, Ca) chelate moxifloxacin and reduce absorption. Administer moxifloxacin 4 hours before or 8 hours after antacids.
Bi/trivalent cations chelate moxifloxacin in the gut, forming insoluble complexes that reduce its bioavailability.
Ensure the dosing interval and monitor the clinical response.
Treatment failure/persistent infection after concurrent dosing.
Separate the doses: moxifloxacin at least 4 hours before or 8 hours after antacids and cation-containing preparations.
DailyMed/FDA (NIH/NLM) — approved Moxifloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1ed191f5-7df5-488c-bb72-91ac0b618d9a ; approved Antacids label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c72f0736-ee20-45b4-baf0-b80f1e3fa9cb — with additional reference: Prontuário Terapêutico do INFARMED, INFARMED (11th ed., 2012)
Calcium cations from dairy products chelate moxifloxacin and reduce its oral absorption.
Take moxifloxacin 4 hours before or 8 hours after dairy products.
DailyMed/FDA (NIH/NLM) — approved Moxifloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1ed191f5-7df5-488c-bb72-91ac0b618d9a
Moxifloxacin can be administered with or without food, with no relevant change in absorption.
Take at the same time every day, with or without food.
DailyMed/FDA (NIH/NLM) — approved Moxifloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1ed191f5-7df5-488c-bb72-91ac0b618d9a
Moxifloxacin prolongs the QT interval significantly; avoid in patients with QT prolongation or risk factors.
Monitor the ECG and electrolytes; avoid QT-prolonging combinations.
DailyMed/FDA (NIH/NLM) — approved Moxifloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1ed191f5-7df5-488c-bb72-91ac0b618d9a
Fluoroquinolones increase the risk of tendinitis and tendon rupture, especially of the Achilles tendon.
Stop at the first sign of tendon pain or inflammation; caution in the elderly and with corticosteroids.
DailyMed/FDA (NIH/NLM) — approved Moxifloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1ed191f5-7df5-488c-bb72-91ac0b618d9a
Fluoroquinolones can affect growing cartilage; avoid in pregnancy unless there is no alternative.
Avoid; use only in severe infections with no safe alternative.
Present in breast milk; avoid breastfeeding during treatment.
No specific contraception required.
DailyMed/FDA (NIH/NLM) — approved Moxifloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1ed191f5-7df5-488c-bb72-91ac0b618d9a
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Broad-spectrum bactericidal fluoroquinolone (including multidrug-resistant pneumococci, atypicals and anaerobes), with a long half-life allowing once-daily dosing. Class adverse effects: tendinopathy/tendon rupture, peripheral neuropathy, CNS effects, QT prolongation and myasthenia gravis exacerbation.
Inhibits bacterial DNA replication by blocking topoisomerases II (DNA gyrase) and IV, preventing supercoiling and chromosome separation during cell division — concentration-dependent bactericidal effect.
Well absorbed from the GI tract; absolute oral bioavailability ~90%; plasma peak ~2 h after dosing; high-fat meals and yoghurt do not affect absorption. Plasma concentrations proportional to dose up to 1200 mg.
Predominantly hepatic phase II metabolism (glucuronide and sulphate conjugation); oxidative CYP metabolism is minor. Mixed excretion: ~20% unchanged in urine and ~25% in faeces; no relevant adjustment in mild/moderate renal or hepatic impairment.
Plasma elimination half-life ~12±1.3 h (8.2-15.6 h); steady state reached after ~3 days with 400 mg once daily.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
