Vancomycin exerts its bactericidal effect by inhibiting cell wall synthesis in Gram-positive bacteria. It binds to the D-alanyl-D-alanine terminus of cell wall precursor units, preventing the incorporation of these units into the peptidoglycan matrix. This inhibition disrupts cell wall integrity, leading to osmotic instability and ultimately bacterial cell death.

Vancomycin is particularly effective against Gram-positive organisms, including:

• Methicillin-resistant Staphylococcus aureus (MRSA)
• Coagulase-negative staphylococci
• Enterococci (including Enterococcus faecalis and Enterococcus faecium)
• Clostridioides difficile (in oral form)

It is not effective against Gram-negative bacteria due to their outer membrane, which prevents vancomycin from reaching its target site.

Vancomycin is primarily used to treat severe infections caused by Gram-positive bacteria, especially when resistance to other antibiotics (e.g., penicillins and cephalosporins) is a concern. Its clinical applications include:

1. Methicillin-resistant Staphylococcus aureus (MRSA) Infections:
   • Skin and soft tissue infections
   • Bacteremia
   • Endocarditis
   • Pneumonia
   • Osteomyelitis
2. Infections Caused by Enterococcus Species:
   • Endocarditis
   • Urinary tract infections (UTIs)
3. Clostridioides difficile-Associated Diarrhea (CDAD):
   • Oral vancomycin is used for severe or recurrent cases.
4. Surgical Prophylaxis:
   • Used in patients with a known MRSA colonization or in hospitals with a high prevalence of MRSA.
5. Other Infections:
   • Meningitis caused by susceptible organisms
   • Empiric therapy for febrile neutropenia in high-risk patients

Vancomycin is available in both intravenous (IV) and oral formulations. The dosage depends on the type and severity of the infection, renal function, and patient weight.

Intravenous Vancomycin

• Adults:
  • Normal renal function: 15–20 mg/kg/dose (actual body weight) every 8–12 hours, not exceeding 2 g per dose.
  • Serious infections (e.g., meningitis, endocarditis): Target trough levels of 15–20 mg/L.
  • Renal impairment: Dose adjustment is required. Consult the BNF or use a dosing calculator.
• Children:
  • Neonates: 10–15 mg/kg every 12–24 hours, depending on gestational age and renal function.
  • Infants and children: 10–15 mg/kg every 6–8 hours.

Oral Vancomycin

• Adults: 125–500 mg every 6 hours for C. difficile infections.
• Children: 5 mg/kg every 6 hours (maximum 500 mg per dose).

Monitoring

• Therapeutic drug monitoring (TDM) is essential for IV vancomycin to ensure efficacy and minimize toxicity.
• Trough levels should be measured just before the fourth dose, targeting:
  • 10–15 mg/L for most infections.
  • 15–20 mg/L for serious infections like meningitis or endocarditis.

Vancomycin is generally well-tolerated, but it can cause several adverse effects, particularly with prolonged use or high doses:

1. Nephrotoxicity:
   • Risk increases with concurrent use of other nephrotoxic drugs (e.g., aminoglycosides).
   • Monitor renal function regularly.
2. Ototoxicity:
   • Hearing loss or tinnitus may occur, especially with high trough levels.
3. Red Man Syndrome:
   • A hypersensitivity reaction characterized by flushing, rash, pruritus, and hypotension.
   • Can be minimized by infusing vancomycin slowly (over at least 1 hour) and pre-treating with antihistamines.
4. Thrombophlebitis:
   • Inflammation at the injection site can occur with IV administration.
5. Gastrointestinal Effects:
   • Nausea, vomiting, and diarrhea (more common with oral vancomycin).
6. Hematologic Effects:
   • Rarely, neutropenia or thrombocytopenia may occur.

1. Renal Impairment:
   • Vancomycin is primarily excreted by the kidneys. Dose adjustments are necessary in patients with impaired renal function.
2. Pregnancy and Lactation:
   • Use only if clearly needed. Vancomycin crosses the placenta and is excreted in breast milk.
3. Elderly Patients:
   • Increased risk of nephrotoxicity and ototoxicity. Monitor closely.
4. Hypersensitivity:
   • Avoid in patients with a known hypersensitivity to vancomycin.
5. Therapeutic Drug Monitoring:
   • Essential to prevent toxicity and ensure therapeutic efficacy.

Vancomycin has several clinically significant drug interactions:

1. Nephrotoxic Drugs (e.g., aminoglycosides, NSAIDs, amphotericin B):
   • Increased risk of nephrotoxicity.
2. Anesthetic Agents:
   • May enhance the risk of histamine release and red man syndrome.
3. Loop Diuretics (e.g., furosemide):
   • May increase the risk of ototoxicity.
4. Cholestyramine and Colestipol:
   • Reduce the absorption of oral vancomycin.
5. Warfarin:

Vancomycin may potentiate the anticoagulant effect

Vancomycin is available under various generic names, including:

• Vancomycin Hydrochloride
• Vancomycin HCl

It is marketed under several brand names, such as Vancocin and Firvanq (oral formulation).