Is vancomycin excreted by the liver?

Vancomycin Excretion Pathway

Vancomycin is primarily excreted by the kidneys through glomerular filtration, not by the liver. About 75% of an administered dose is excreted unchanged in urine within the first 24 hours in patients with normal renal function 1.

Pharmacokinetics of Vancomycin

Renal Excretion

• Approximately 75% of administered vancomycin is excreted unchanged in urine by glomerular filtration within the first 24 hours in patients with normal renal function 1
• Mean plasma clearance is about 0.058 L/kg/h, and mean renal clearance is about 0.048 L/kg/h 1
• The elimination half-life of vancomycin from plasma is 4-6 hours in subjects with normal renal function 1
• Renal dysfunction significantly slows excretion of vancomycin, with the average half-life increasing to 7.5 days in anephric patients 1

Metabolism and Hepatic Processing

• There is no apparent metabolism of vancomycin 1
• Unlike many other antibiotics, vancomycin does not undergo significant hepatic metabolism 2
• When administered intravenously, vancomycin is excreted primarily unchanged in the urine by glomerular filtration 2

Clinical Implications

Dosing Considerations

• Vancomycin dosage must be adjusted in patients with renal impairment due to its primary renal excretion pathway 3
• Intravenous vancomycin has no effect on Clostridioides difficile infection since the antibiotic is not excreted into the colon 4
• For treatment of C. difficile infection, oral vancomycin is preferred as it remains in the gut lumen and is not significantly absorbed systemically 4

Liver Disease Considerations

• In patients with liver disease and normal renal function, total clearance of vancomycin is generally not affected 5
• In patients with both impaired liver and renal functions, particularly with obstructive jaundice, the unbound fraction of vancomycin may increase while renal excretion is delayed 5
• Caution should be exercised when administering conventional doses of vancomycin to patients with combined hepatic and renal dysfunction as blood concentrations may increase excessively 5

Protein Binding and Distribution

• Vancomycin is approximately 55% serum protein bound at concentrations of 10-100 mcg/mL 1
• The distribution coefficient ranges from 0.3 to 0.43 L/kg 1
• After IV administration, inhibitory concentrations are present in pleural, pericardial, ascitic, and synovial fluids; in urine; in peritoneal dialysis fluid; and in atrial appendage tissue 1

Special Considerations

• Total systemic and renal clearance of vancomycin may be reduced in elderly patients 1
• Vancomycin does not readily cross normal meninges but can penetrate into spinal fluid when meninges are inflamed 1
• About 60% of an intraperitoneal dose of vancomycin administered during peritoneal dialysis is absorbed systemically in 6 hours 1

Understanding vancomycin's primarily renal excretion pathway is crucial for appropriate dosing and monitoring, especially in patients with impaired renal function where dose adjustments are necessary to prevent toxicity.