What is the starting dose of vancomycin (Vancomycin hydrochloride) for a patient with soft tissue infection weighing 116kg?

Vancomycin Starting Dose for 116kg Patient with Soft Tissue Infection

For a 116kg patient with soft tissue infection, administer a loading dose of 2900mg (25 mg/kg based on actual body weight) intravenously, followed by maintenance dosing of 2000mg every 8-12 hours.

Loading Dose Calculation

• A loading dose of 25-30 mg/kg based on actual body weight is recommended for serious infections to rapidly achieve therapeutic concentrations 1
• For this 116kg patient: 25 mg/kg × 116kg = 2900mg loading dose 1
• The maximum single dose should not exceed 2000mg per the FDA label, so this loading dose would be administered as 2000mg followed shortly by 900mg, or rounded to two 1500mg doses 2
• However, current expert consensus supports loading doses up to 3000mg when clinically indicated for severe infections 1

Maintenance Dosing Strategy

• Maintenance dosing should be 15-20 mg/kg every 8-12 hours based on actual body weight 3, 1
• For this 116kg patient: 15-20 mg/kg × 116kg = 1740-2320mg per dose 1
• Practical dosing: 2000mg every 8-12 hours is appropriate 3
• The every-8-hour interval is preferred over every-12-hour for critically ill patients or those with augmented renal clearance 4, 5

Administration Guidelines

• Infuse each dose over at least 60 minutes, with a maximum rate of 10 mg/min 2
• For a 2000mg dose: minimum infusion time is 200 minutes (3.3 hours) at 10 mg/min, but 60 minutes is acceptable if concentration is ≤5 mg/mL 2
• Use concentrations ≤5 mg/mL to minimize infusion-related reactions; up to 10 mg/mL may be used in fluid-restricted patients 2

Critical Monitoring Parameters

• Target trough concentration of 15-20 μg/mL for serious soft tissue infections 1, 6
• Obtain first trough level before the 4th or 5th dose (at steady state) 1
• The optimal pharmacodynamic target is AUC/MIC ratio >400 1, 6
• Monitor renal function closely, as nephrotoxicity risk increases with higher trough levels 1, 4

Common Pitfalls to Avoid

• Do not use fixed 1000mg doses without weight-based calculation—this leads to significant underdosing in patients >70kg 1
• Avoid delaying the loading dose, as subtherapeutic initial concentrations are common even with aggressive dosing 4, 5
• If vancomycin MIC is ≥2 μg/mL, strongly consider alternative agents (daptomycin, linezolid, ceftaroline) as target AUC/MIC ratios may not be achievable 1, 6
• In soft tissue infections with reduced tissue perfusion, vancomycin penetration may be compromised, potentially requiring alternative agents for MIC >1 μg/mL 7

Context for Soft Tissue Infections

• For necrotizing soft tissue infections or severe cellulitis where MRSA is suspected, vancomycin is appropriate empiric therapy 3
• Empiric therapy should be broad; vancomycin is often combined with piperacillin-tazobactam or a carbapenem for polymicrobial coverage 3
• If methicillin-susceptible organisms are identified, de-escalate to narrower spectrum agents 3