Vancomycin Drug Dosing

Overview

Standard Dosing Regimens

Adults (Normal Renal Function)

Note: The traditional 1 g q12h regimen typically does NOT achieve trough concentrations or AUC/MIC ratios needed for serious infections. Higher starting doses (45-60 mg/kg/day) are recommended for those.

• Katzung's Basic and Clinical Pharmacology, 16th Ed., p. 1257
• Goodman & Gilman's Pharmacological Basis of Therapeutics, p. 1181

Pediatric Dosing

For neonates <2 kg, use the lower dosage range. After the first month of life, pediatric doses apply.

C. difficile Colitis (Oral)

Note: Recent guidelines prefer fidaxomicin over oral vancomycin due to lower relapse rates.

Renal Dosing Adjustments

• Katzung's Basic and Clinical Pharmacology, 16th Ed.

Obesity Dosing

• Vancomycin has increased volume of distribution (Vd) AND increased clearance in obese patients, leading to lower troughs.
• Loading dose: 20-25 mg/kg based on total body weight (TBW).
• Caution: Doses >4 g/day are associated with vancomycin-induced nephrotoxicity.
• Maintenance doses should be individualized to peak and trough levels.
• Rosen's Emergency Medicine, p. 2887

Therapeutic Drug Monitoring (TDM)

Current Standard: AUC/MIC-Guided Dosing (Preferred)

• AUC can be estimated using Bayesian software/online calculators, or by obtaining one or two serum levels during a dosing interval.
• AUC-based monitoring has been shown to allow lower daily doses, lower trough concentrations, and decreased rates of acute kidney injury (AKI) without compromising efficacy.
• Random levels for Bayesian modeling can be drawn at any time after at least one dose.

Trough-Based Monitoring (Alternative When AUC Not Available)

• Trough is drawn within 30 minutes prior to a dose, at steady state (typically before the 4th dose).
• A trough of 10-15 mg/L in non-critically ill patients will usually achieve AUC >400 mg·h/L.
• Goodman & Gilman's, p. 1181

Key Pharmacokinetics

• Infusion rate: No more than 1 g per hour to avoid infusion-related reactions.
• Katzung's, p. 1256; Tietz Laboratory Medicine, 7th Ed.

Adverse Effects

Clinical Indications

• MRSA infections: Bacteremia, endocarditis, osteomyelitis, pneumonia, meningitis (first-line)
• Enterococcal endocarditis: + aminoglycoside (in serious penicillin allergy)
• Pneumococcal meningitis (PCN-resistant): + cefotaxime/ceftriaxone ± rifampin
• C. difficile colitis: Oral formulation only (IV is not effective for this)
• MSSA infections: Vancomycin is inferior to anti-staphylococcal penicillins (nafcillin/oxacillin) for MSSA - use beta-lactams when susceptible

Quick Summary Card

VANCOMYCIN DOSING SUMMARY

IV (Systemic):
  Normal renal:  30-60 mg/kg/day ÷ q8-12h
  Serious MRSA:  45-60 mg/kg/day (target AUC/MIC 400-600)
  Children:      40-60 mg/kg/day ÷ q6-8h
  HD patients:   1g load → 500 mg post-dialysis

Oral (C. diff only):
  Mild-mod:      125 mg QID
  Severe:        500 mg QID

Monitoring (preferred):
  AUC/MIC = 400-600 mg·h/L (Bayesian method)

Monitoring (alternative):
  Trough: 10-15 (mild) or 15-20 (serious) mcg/mL

Infusion: max rate 1 g/hour (slow to prevent Red Man)
Adjust for CrCl — directly proportional

• Katzung's Basic and Clinical Pharmacology, 16th Edition - Glycopeptides chapter
• Goodman & Gilman's Pharmacological Basis of Therapeutics - Cell wall inhibitors
• Tietz Textbook of Laboratory Medicine, 7th Edition - TDM
• Rosen's Emergency Medicine - Dosing in obesity
• ASHP/IDSA/SIDP 2020 Consensus Guidelines on vancomycin TDM (AUC-guided monitoring)
• Safe and effective use of vancomycin - PMC 2025