What are the administration guidelines for fluoroquinolones (Fluoroquinolone antibiotics)?

Fluoroquinolone Administration Guidelines

Fluoroquinolones should be administered orally or intravenously at specific dosing intervals based on the agent selected, with ciprofloxacin dosed at 500-750 mg every 12 hours and levofloxacin at 500-750 mg once daily, while strictly avoiding concurrent administration with divalent/trivalent cations by at least 2 hours. 1, 2

Dosing Regimens by Agent

Ciprofloxacin

• Oral dosing: 500 mg twice daily for most infections; 750 mg twice daily for severe infections 3, 1
• IV dosing: 400 mg every 12 hours 4
• Pediatric dosing: 20-40 mg/kg/day divided every 12 hours orally (maximum 750 mg/dose); 20-30 mg/kg/day divided every 8-12 hours IV (maximum 400 mg/dose) 5
• Bioavailability approaches 100%, allowing seamless transition between oral and IV routes 6, 7

Levofloxacin

• Adult dosing: 500-750 mg once daily (oral or IV) 3, 4, 2
• Pediatric dosing: 16-20 mg/kg/day divided every 12 hours (ages 6 months-5 years) or 10 mg/kg once daily (ages ≥5 years), maximum 750 mg/dose 5, 2
• Offers convenience of once-daily dosing compared to ciprofloxacin's twice-daily regimen 8, 6

Critical Administration Requirements

Timing with Chelating Agents

• Administer fluoroquinolones at least 2 hours before or 6 hours after antacids containing magnesium/aluminum, sucralfate, iron supplements, zinc, calcium supplements, or didanosine buffered formulations 5, 1, 2
• These divalent and trivalent cations can reduce fluoroquinolone absorption by up to 90%, potentially leading to treatment failure 9, 10
• Even when doses are separated by hours, significant inhibition can occur 9

Food and Fluid Considerations

• Fluoroquinolones may be taken with or without food 1, 2
• Exception: Do not take with dairy products (milk, yogurt) or calcium-fortified juices alone, as absorption may be significantly reduced 1
• May be taken with a meal that contains dairy products 1
• Maintain adequate hydration to prevent crystalluria, particularly in alkaline urine 1, 2

Duration of Therapy by Indication

• Pyelonephritis: 5-7 days for fluoroquinolones 3
• Complicated UTI: 7-10 days 5
• Traveler's diarrhea: 3-7 days 5
• Salmonella gastroenteritis (HIV patients): 14 days 5
• Tuberculosis (MDR): Long-term as part of combination therapy 5

Renal Dose Adjustments

Ciprofloxacin

• CrCl <50 mL/min: Reduce to 750-1000 mg three times weekly 5
• Not removed by hemodialysis; no supplemental doses needed 5

Levofloxacin

• CrCl 20-49 mL/min: 750 mg initial dose, then 750 mg every 48 hours 2
• CrCl 10-19 mL/min: 750 mg initial dose, then 500 mg every 48 hours 2
• Careful monitoring required as 80% eliminated unchanged in urine 6

Special Population Considerations

Pediatric Patients

• Generally avoid in children <18 years due to concerns about cartilage and bone toxicity 5
• Exception: May be used for multidrug-resistant tuberculosis or when no alternatives exist 5
• Parents should be informed of joint-related risks and monitor for tendon/joint problems 5, 2

Pregnant Women

• Contraindicated in pregnancy due to teratogenic effects 5
• Alternative antibiotics (ampicillin, cefotaxime, ceftriaxone, TMP-SMZ) should be used 5

Elderly Patients (>60 years)

• Higher risk for tendon disorders, especially if taking corticosteroids or have had organ transplants 1, 2
• Monitor closely for CNS effects (dizziness, confusion) and tendinopathy 4
• No dose adjustment needed based on age alone if renal function is normal 6

Critical Drug Interactions

Theophylline

• Ciprofloxacin and enoxacin significantly inhibit theophylline metabolism, potentially requiring dose reduction 9, 10, 11
• Ofloxacin and levofloxacin have minimal effects 9, 10
• Monitor theophylline levels closely 1

Warfarin

• May potentiate anticoagulant effects and increase INR 2, 10
• Monitor INR closely and watch for bleeding 2

Tizanidine

• Absolute contraindication: Ciprofloxacin increases tizanidine exposure 7-10 fold, causing severe hypotension and sedation 1
• Do not use together 1

Corticosteroids

• Concurrent use significantly increases risk of tendon rupture 5, 1
• Avoid combination when possible 5

Common Pitfalls to Avoid

• Do not use fluoroquinolones as first-line agents for drug-susceptible tuberculosis except when first-line drugs cannot be used 5
• Avoid empiric use in areas with >10% fluoroquinolone resistance without adding initial parenteral agent 3, 8
• Do not prescribe for patients already on fluoroquinolone prophylaxis as empiric therapy 5
• Discontinue immediately if tendon pain, swelling, or inflammation develops 5, 1, 2
• Stop treatment if signs of peripheral neuropathy (pain, burning, tingling, numbness, weakness) occur, as this may be irreversible 1, 2
• Avoid excessive sun/UV exposure due to photosensitivity risk; discontinue if sunburn-like reaction occurs 1, 2
• Do not use in patients with history of QT prolongation or those taking Class IA or III antiarrhythmics 2

Monitoring During Therapy

• Advise patients to limit high-intensity physical activity during treatment to reduce tendon injury risk 5
• Monitor for CNS effects (dizziness, headache, confusion, seizures) particularly in patients with seizure history 1, 11
• Watch for hypersensitivity reactions even after single dose 1
• Assess for Clostridioides difficile infection if diarrhea develops during or after treatment 1, 2