What is the dose of norfloxacin (Norflox) for spontaneous bacterial peritonitis (SBP) prophylaxis?

Norfloxacin Dosing for SBP Prophylaxis

The recommended dose of norfloxacin for spontaneous bacterial peritonitis (SBP) prophylaxis is 400 mg once daily taken orally. 1, 2

Indications for SBP Prophylaxis

Secondary Prophylaxis

• All patients who have recovered from an episode of SBP should receive indefinite prophylaxis with norfloxacin 400 mg daily until liver transplantation or resolution of ascites 1, 2
• This is strongly supported by evidence showing norfloxacin reduces SBP recurrence from 68% to 20% 1

Primary Prophylaxis

Indicated for high-risk patients with:

• Low ascitic fluid protein (<15 g/L) AND
• Advanced liver disease (Child-Pugh score ≥9 with serum bilirubin >3 mg/dL) OR
• Impaired renal function (serum creatinine ≥1.2 mg/dL, BUN ≥25 mg/dL) OR
• Serum sodium ≤130 mEq/L 1, 2

Alternative Prophylactic Regimens

If norfloxacin is unavailable or contraindicated, consider:

• Ciprofloxacin 500 mg once daily 2, 3
• Trimethoprim-sulfamethoxazole 800/160 mg daily (but may have more adverse events) 2

Duration of Prophylaxis

• Secondary prophylaxis: Continue indefinitely until liver transplantation or death 1, 2
• Primary prophylaxis: Long-term use recommended in high-risk patients 1, 2

Important Considerations

Monitoring

• Regular assessment of renal function (every 1-3 months)
• Periodic cultures to detect resistant organisms 2

Potential Pitfalls

1. Antibiotic resistance: Long-term use of quinolones may lead to resistant infections. Consider discontinuing quinolone prophylaxis if infection with quinolone-resistant bacteria occurs 1

2. Concomitant medications:

   • Proton pump inhibitors (PPIs) may increase SBP risk and should be restricted to those with clear indications 1
   • For patients already on rifaximin for hepatic encephalopathy, there are insufficient data to guide whether norfloxacin should be added or if rifaximin alone is sufficient 1

3. Prognosis: Patients who have had SBP have poor long-term survival (30-50% at 1 year) and should be considered for liver transplantation 1

Special Situations

Weekly ciprofloxacin (500 mg once weekly) has shown non-inferiority to daily norfloxacin in some studies 3, but daily norfloxacin remains the standard of care based on the most robust evidence and clinical guidelines 1, 2.

The addition of probiotics to norfloxacin has not been shown to improve efficacy in SBP prophylaxis 4.