What is the dose of ciprofloxacin (Cipro) for a patient with impaired renal function?

Ciprofloxacin Dosing in Renal Impairment

For patients with renal impairment, ciprofloxacin requires dose adjustment based on creatinine clearance: use 250-500 mg every 12 hours for moderate impairment (CrCl 30-50 mL/min), 250-500 mg every 18 hours for severe impairment (CrCl 5-29 mL/min), and 250-500 mg every 24 hours after dialysis for patients on hemodialysis or peritoneal dialysis. 1

Dosing Algorithm by Renal Function

Moderate Renal Impairment (CrCl 30-50 mL/min)

• Administer 250-500 mg orally every 12 hours 1
• This represents a reduction from the standard dose due to decreased renal clearance, which accounts for approximately 67% of total ciprofloxacin elimination 2

Severe Renal Impairment (CrCl 5-29 mL/min)

• Administer 250-500 mg orally every 18 hours 1
• The elimination half-life extends to approximately 8.7 hours in severe renal failure compared to 4.4 hours in normal function, necessitating interval prolongation 3
• Renal clearance of ciprofloxacin correlates linearly with glomerular filtration rate 4

Hemodialysis or Peritoneal Dialysis

• Administer 250-500 mg orally every 24 hours, given after dialysis 1
• Ciprofloxacin is partially removed by hemodialysis with a dialyzer extraction ratio of 23% and dialysis clearance of 40 mL/min 4
• Post-dialysis administration prevents premature drug removal and ensures adequate drug exposure 1

Critical Dosing Considerations

Interval Prolongation vs. Dose Reduction

• Prolonging the administration interval is pharmacodynamically superior to reducing the dose in renal failure 5
• Simulations demonstrate bacterial eradication on day 3 with interval prolongation (500 mg every 24 hours) versus day 6 with dose reduction (250 mg every 12 hours) in renal failure 5
• This advantage occurs because ciprofloxacin exhibits concentration-dependent killing, requiring adequate peak concentrations above the minimum inhibitory concentration 5

Pathogen Susceptibility Impact

• For pathogens with MIC ≤ 0.125 mg/L, standard adjusted doses achieve adequate AUC/MIC ratios >125 6
• For less susceptible pathogens (MIC ≥ 0.5 mg/L), even the standard 400 mg daily dose may be insufficient in renal impairment 6
• In critically ill patients with preserved renal function and resistant pathogens, doses up to 600 mg four times daily may be required 6

Common Pitfalls to Avoid

• Do not assume normal serum creatinine indicates normal renal function, particularly in elderly patients with reduced muscle mass where creatinine clearance may be severely reduced despite "normal" creatinine levels 7
• Avoid giving ciprofloxacin before dialysis sessions, as this results in premature drug removal and subtherapeutic levels 1
• Do not use simple dose reduction without interval adjustment in severe renal impairment, as this compromises the concentration-dependent bactericidal activity 5
• The maximal dose reduction of 50% should be initiated when creatinine clearance falls to 20-30 mL/min/1.73 m², maintaining the every-12-hour schedule at this threshold 2

Pharmacokinetic Rationale

• Total plasma clearance decreases from 770 mL/min in normal subjects to 378 mL/min in severe renal impairment (CrCl <8 mL/min) 4
• Urinary recovery of unchanged drug drops from 40% in normal function to only 8% in severe renal failure 4
• Renal clearance far exceeds glomerular filtration rate due to net tubular secretion, which is inhibited by probenecid 2
• Approximately 25% of ciprofloxacin elimination occurs through non-renal pathways (biliary excretion and metabolism), explaining why anephric patients retain approximately 50% of normal clearance 2