Vancomycin Empiric Dosing for Adults with Normal Renal Function
For empiric coverage in adults with normal renal function, administer vancomycin 15–20 mg/kg (actual body weight) IV every 8–12 hours, with a loading dose of 25–30 mg/kg for seriously ill patients suspected of having MRSA infection. 1
Standard Dosing Regimen
Weight-based dosing of 15–20 mg/kg every 8–12 hours is the recommended approach for most adult patients with normal renal function, with a maximum single dose not exceeding 2 g 1, 2
For non-obese patients with non-severe infections (such as uncomplicated cellulitis), traditional fixed doses of 1 g every 12 hours are typically adequate 1, 3
The FDA label supports a usual daily dose of 2 g divided as either 500 mg every 6 hours or 1 g every 12 hours for adults with normal renal function 2
Loading Dose Strategy
For seriously ill patients with suspected MRSA infection (sepsis, pneumonia, bacteremia, endocarditis, necrotizing fasciitis, meningitis, or osteomyelitis), administer a loading dose of 25–30 mg/kg based on actual body weight to rapidly achieve therapeutic concentrations 1
This loading dose is critical in critically ill patients because fluid resuscitation expands the volume of distribution, delaying achievement of therapeutic levels with standard dosing alone 1
Never use fixed 1-gram loading doses—they fail to achieve early therapeutic levels in most patients, particularly those weighing more than 70 kg 1
The loading dose should be infused over 2 hours with antihistamine premedication to prevent red man syndrome 1, 3
Infusion Guidelines
For doses >1 g, extend the infusion period to 1.5–2 hours to minimize infusion-related adverse effects 1, 3
The FDA recommends concentrations no more than 5 mg/mL and rates no more than 10 mg/min in adults 2
Therapeutic Monitoring
Target trough concentrations of 15–20 µg/mL for serious infections (bacteremia, endocarditis, osteomyelitis, meningitis, pneumonia, necrotizing fasciitis) 1, 4
For non-severe infections, target trough levels of 10–15 µg/mL 1
Obtain the first trough level before the fourth or fifth dose when steady-state is expected 1, 4
The pharmacodynamic target is an AUC/MIC ratio >400, which correlates with clinical efficacy 1, 4
Special Populations
Obese Patients
Always use actual body weight for dosing calculations in obese patients—never ideal body weight 1
Conventional 1 g every 12 hours dosing leads to subtherapeutic levels in obese patients 1, 3
Mandatory trough monitoring is required for morbidly obese patients (BMI ≥40 kg/m²) 1
Patients with Renal Impairment
The loading dose remains unchanged regardless of renal function—give the full 25–30 mg/kg 1
Only maintenance doses require adjustment for renal impairment, typically by extending the dosing interval 1, 2
Critical Pitfalls to Avoid
Never reduce the loading dose based on renal dysfunction—this is the most common error and delays therapeutic concentrations 1
Avoid fixed 1-gram dosing in critically ill or obese patients (>70 kg)—it consistently produces subtherapeutic levels 1
Do not target high trough levels (15–20 µg/mL) for non-severe infections—this unnecessarily increases nephrotoxicity risk 1
If vancomycin MIC is ≥2 µg/mL, switch to an alternative agent (daptomycin, linezolid, or ceftaroline) because the target AUC/MIC ratio >400 is unlikely to be achievable 1, 4
Nephrotoxicity risk increases significantly when trough levels exceed 15 µg/mL, especially with concurrent nephrotoxic agents (aminoglycosides, piperacillin-tazobactam, NSAIDs, amphotericin B) 1