What are the side effects of vancomycin (Vanco) when serum levels are elevated?

Side Effects of Elevated Vancomycin Serum Levels

High vancomycin levels can cause acute kidney injury (AKI), ototoxicity, and infusion-related reactions, with nephrotoxicity being the most common serious adverse effect. 1, 2

Nephrotoxicity

• Acute kidney injury is characterized by increases in serum creatinine of ≥0.5 mg/dL or a 150% increase from baseline 1, 3
• Risk of nephrotoxicity significantly increases with sustained trough concentrations >20 μg/mL 1, 4
• Interstitial nephritis has been reported in patients receiving vancomycin 2
• Nephrotoxicity risk increases with:
  • Concomitant administration of other nephrotoxic agents 2, 4
  • Pre-existing renal impairment 2, 4
  • Co-morbidities that predispose to renal impairment 2
  • Prolonged therapy (>7 days) 4
  • High daily doses (>4 g/day) 4

Ototoxicity

• Can manifest as hearing loss, tinnitus, vertigo, or dizziness 2, 5
• May be transient or permanent 2
• Higher risk in patients with:
  • Underlying hearing loss 2
  • Renal dysfunction 2, 5
  • Concomitant therapy with another ototoxic agent (e.g., aminoglycosides) 2
• Despite concerns, a recent study found only 8% of patients on long-term vancomycin therapy experienced worsening hearing, with only 3% developing moderate-to-severe hearing loss 6

Infusion-Related Reactions

• Rapid infusion can cause anaphylactoid reactions including hypotension, wheezing, dyspnea, urticaria, or pruritus 2
• "Red neck syndrome" - flushing of the upper body during rapid infusion 2
• Pain and muscle spasm of chest and back 2
• These reactions usually resolve within 20 minutes but may persist for several hours 2

Hematologic Effects

• Reversible neutropenia, usually starting 1 week or more after therapy initiation or after a total dose of >25g 2
• Thrombocytopenia (rare) 2
• Reversible agranulocytosis (granulocytes <500/mm³) has been reported rarely 2

Dermatologic Reactions

• Severe dermatologic reactions can occur, including:
  • Toxic epidermal necrolysis (TEN) 2
  • Stevens-Johnson syndrome (SJS) 2
  • Drug reaction with eosinophilia and systemic symptoms (DRESS) 2
  • Acute generalized exanthematous pustulosis (AGEP) 2
  • Linear IgA bullous dermatosis (LABD) 2
• Rashes, including exfoliative dermatitis 2

Gastrointestinal Effects

• Pseudomembranous colitis (Clostridium difficile-associated diarrhea) 2
• Nausea 2

Monitoring and Management

• Regular monitoring of trough serum vancomycin concentrations is essential for patients receiving prolonged courses of therapy 1, 3
• Monitor renal function with serum creatinine measurements 1, 3
• For patients with symptoms of ototoxicity, consider audiometric evaluation 1
• If elevated levels are detected:
  • Hold the next scheduled dose and recheck the trough level before administering subsequent doses 1
  • Once the trough level decreases to the target range (15-20 mg/L for serious infections), resume vancomycin at a reduced dose or with an extended dosing interval 1
  • In cases of severe toxicity, especially with significant renal impairment, consider alternative antibiotics 1

Common Pitfalls in Managing Vancomycin Toxicity

• Failing to adjust dosage in patients with renal dysfunction 2
• Administering vancomycin too rapidly (should be given over at least 60 minutes) 2
• Not monitoring trough levels in high-risk patients 3
• Continuing vancomycin despite signs of toxicity 1
• Overlooking drug interactions with other nephrotoxic agents 2, 4