Moxifloxacin

1. Health Canada Product Monograph — Moxifloxacin

• Acute bacterial rhinosinusitis, community-acquired pneumonia, and acute bacterial exacerbation of chronic bronchitis caused by susceptible organisms, in adult patients unable to take a beta-lactam antibiotic (e.g., severe penicillin allergy) or who have failed first-line therapy.
• Because of its serious adverse-effect profile, reserve for infections without a suitable narrower-spectrum or better-tolerated alternative.

Contraindicated in pregnancy. Confirm pregnancy status and discuss alternative therapy with the prescriber before dispensing.

• Avoid in pregnancy. Fluoroquinolones cause arthropathy (joint/cartilage damage) in juvenile animals; this risk is considered to extend to the developing fetus. Safer alternatives are usually available for the infections moxifloxacin treats.

• Caution is advised; avoid repeated or prolonged exposure while breastfeeding given the fluoroquinolone-class arthropathy risk in juvenile animals, and observe the breastfed infant for GI symptoms if used.

• Older adults, particularly those over 60 years of age, are at increased risk of severe tendon disorders including tendon rupture, further increased with concurrent corticosteroid use.

• Not authorized for use in children — safety and effectiveness have not been established, and fluoroquinolone-class arthropathy risk in juvenile animals applies.

• Adults only: 400 mg PO or IV once daily.
• No renal dose adjustment is required — unlike levofloxacin, moxifloxacin is primarily eliminated hepatically, so the same 400 mg once-daily dose is used regardless of renal function.
• Duration and route depend on the specific infection being treated (e.g., 5-7 days for acute bacterial rhinosinusitis).
• Tablets can be taken without regard to meals; avoid taking simultaneously with antacids, sucralfate, or multivalent cation products (see Drug interactions).

If overdose is suspected, seek emergency medical attention immediately or contact your regional Poison Control Centre without delay.

• No specific antidote; overdose management is supportive, with attention to QT interval monitoring given the pronounced QT-prolongation risk of this specific fluoroquinolone.

• Nausea, headache, dizziness, GI upset.

Serious side effects require immediate discussion with the prescriber or emergency care.

• Boxed warning: disabling and potentially permanent tendinitis and tendon rupture — can occur within hours of the first dose; risk is higher in patients over 60, those also taking a corticosteroid, and organ transplant recipients.
• Boxed warning: peripheral neuropathy that can be irreversible.
• Boxed warning: central nervous system effects, including seizures and psychiatric effects (confusion, hallucinations, anxiety, depression, rarely suicidal thoughts).
• QT interval prolongation — more pronounced with moxifloxacin than with most other fluoroquinolones; avoid in patients with known QT prolongation, uncorrected hypokalemia, or concurrent Class IA/Class III antiarrhythmic use, and use with particular caution in liver cirrhosis, where pre-existing QT prolongation cannot be excluded.
• Cases of severe liver injury, including liver failure, have been reported.
• Exacerbation of myasthenia gravis symptoms — avoid in patients with known myasthenia gravis.
• Risk of aortic aneurysm and dissection, particularly in older patients and those with a history of aneurysm, hypertension, or connective tissue disorders.
• Clostridioides difficile-associated diarrhea.

• Use with caution in patients with a history of seizure disorder or other risk factors for seizures.
• Use with caution in patients at risk of tendon problems, including those on concurrent corticosteroids and adults over 60.

• Known hypersensitivity to moxifloxacin or any other quinolone antimicrobial.
• History of tendinitis or tendon rupture associated with previous fluoroquinolone use.
• Myasthenia gravis.
• Known QT prolongation, uncorrected hypokalemia, or concurrent Class IA/Class III antiarrhythmic therapy.

• Antacids, sucralfate, multivalent cation products (magnesium, aluminum, iron, zinc), and dairy products: significantly reduce absorption — separate administration by several hours.
• Warfarin: may increase anticoagulant effect — monitor INR.
• QT-prolonging drugs and Class IA/Class III antiarrhythmics: increased risk of arrhythmia — avoid combination.
• NSAIDs: may increase seizure risk when combined with a fluoroquinolone.
• Corticosteroids: increased risk of tendon rupture, particularly in older adults.

• Can be taken with or without food; separate from dairy products and calcium-fortified foods as above.

• Once daily, at approximately the same time each day.

• Store tablets at room temperature. Store IV solution per product labelling, protected from light; do not freeze.

• Complete the full prescribed course even if you feel better early.
• Stop the medication and contact your prescriber right away if you notice tendon pain, swelling, or a snapping/popping sensation in a joint (especially the Achilles tendon), or any new numbness, tingling, burning, or weakness.
• Avoid taking this medication at the same time as antacids, calcium, iron, or magnesium supplements — separate by several hours.
• Seek medical attention promptly for irregular heartbeat, severe skin rash, sudden chest or back pain, or new confusion.
• This medication should not be used in pregnancy or in children.