Generic Name

Levaquin

Mechanism

• Levofloxacin binds to bacterial topoisomerase IV (primary target) and, to a lesser extent, DNA gyrase.
• This interaction stabilizes the enzyme‑DNA complex after strand cleavage, preventing re‑ligation and leading to rapid bacterial death.
• The drug exerts a bactericidal effect with a rapid kill rate against both aerobic and facultatively anaerobic organisms.

Pharmacokinetics

• Absorption: Oral bioavailability > 90 % with no need for acid pretreatment.
• Distribution: Extensive tissue penetration (volume of distribution ≈ 1 L/kg); excellent penetration into CSF, pleural fluid, and bone.
• Metabolism: Minimal hepatic metabolism (≈ 20 %); primarily renally excreted unchanged (~70 %).
• Half‑life: 6–8 h → supports twice‑daily dosing (q12 h).
• Drug interactions: Chelates with divalent/trivalent cations (e.g., Ca²⁺, Mg²⁺, Al³⁺); antacids should be spaced 1–2 h before or after dosing.

Indications

• Community‑acquired pneumonia (CAP)
• Acute bacterial exacerbation of chronic bronchitis
• Complicated urinary tract infection (cUTI) and acute cystitis
• Skin and soft‑tissue infections (SSTIs)
• Osteomyelitis, endocarditis, and other severe Gram‑negative bacterial infections

Contraindications

• Hypersensitivity to levofloxacin or any fluoroquinolone.
• Prolonged QT interval or concomitant QT‑prolonging drugs (e.g., quinidine).
• Pregnancy (Category D) & breastfeeding (Category C) – use only if benefits outweigh risks.
• Severe renal impairment (CrCl < 30 mL/min) – dose adjustment required.
• Warn: Tendonitis/rupture (especially posterior tibialis and Achilles), CNS toxicity (seizures, hallucinations), photosensitivity, myelosuppression, Clostridioides difficile colitis.

Dosing

• Adults:
• 500 mg PO or IV q12 h for uncomplicated infections.
• 750 mg PO or IV q12 h for CAP, SSTIs, osteomyelitis.
• Pediatrics:
• 15–20 mg/kg PO q12 h (max 750 mg).
• Renal adjustment:
• CrCl 30–50 mL/min: 500 mg q24 h.
• CrCl < 30 mL/min: 250 mg q24 h or 500 mg q48 h.
• Administration tips:
• Take 1–2 h before or after antacids/supplements.
• Avoid NSAIDs that reduce renal clearance (e.g., ibuprofen).
• For IV route, dilute 500 mg in 100 mL 5% dextrose; infuse over 30–45 min.

Adverse Effects

• Common:
• Gastrointestinal upset (nausea, vomiting, abdominal pain, diarrhea)
• Headache, dizziness, insomnia.
• Serious:
• Tendonitis/rupture (high risk after 3 months or with glucocorticoid use).
• CNS: seizures, anxiety, hallucinations, myoclonus.
• Cardiac: QT prolongation, arrhythmias.
• Hematologic: leukopenia, neutropenia.
• Clostridioides difficile colitis (evidenced by fulminant diarrhea).

Monitoring

• Baseline renal function (creatinine, eGFR).
• QT interval on ECG in patients with cardiac risk factors or on co‑administration of QT‑distancing drugs.
• Liver function tests if symptomatic or if hepatotoxic medications are co‑administered.
• Signs of tendon injury (pain, swelling, or limited motion).
• CNS symptoms (seizures, hallucinations).

Clinical Pearls

• Synergistic combinations: High‑dose levofloxacin (750 mg q12 h) paired with ampicillin or ceftriaxone provides superior efficacy for intra‑abdominal infections, reducing duration of therapy.
• Steroid interaction: Levofloxacin competes with dexamethasone for albumin binding; co‑administration may raise free steroid levels—consider dose adjustment if clinically necessary.
• Renal dosing: For patients with CrCl < 30 mL/min, extend dosing interval to q24 h to prevent drug accumulation while maintaining bactericidal concentrations.
• Photosensitivity vigilance: Counsel patients to use broad‑spectrum sunscreen and wear protective clothing during prolonged sun exposure.
• Tendon prophylaxis: Encourage patient education on tendon pain or sudden swelling, especially in athletes or elderly individuals. Early reporting can prevent rupture.

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• *All information reflects current evidence and pharmacokinetic profiles as of 2024. Clinicians should review patient‑specific factors and local antimicrobial stewardship guidelines before prescribing.*