Vancomycin is a glycopeptide antibiotic used to treat serious infections caused by Gram-positive bacteria, particularly those resistant to other antibiotics. Here are some key points about vancomycin.
Mechanism of Action
- Inhibits cell wall synthesis: Vancomycin binds to the D-alanyl-D-alanine terminus of cell wall precursor units, preventing the incorporation of these units into the peptidoglycan matrix. This inhibits cell wall synthesis and leads to cell lysis and death.
Indications
- Methicillin-resistant Staphylococcus aureus (MRSA): Commonly used for MRSA infections, including skin infections, pneumonia, and bloodstream infections.
- Clostridioides difficile (C. diff): Used orally for severe cases of C. difficile-associated diarrhea (though metronidazole and fidaxomicin are often preferred).
- Other Gram-positive infections: Effective against other Gram-positive bacteria, including Enterococcus species (including vancomycin-resistant enterococci when combined with other agents) and Streptococcus species.
Administration
- Intravenous (IV): For systemic infections.
- Oral: For gastrointestinal infections like C. difficile (not absorbed systemically when taken orally).
Pharmacokinetics
- Absorption: Poor oral absorption; must be given IV for systemic infections.
- Distribution: Widely distributed in body tissues and fluids, including pleural, pericardial, synovial, and ascitic fluids.
- Excretion: Primarily renal; dosage adjustment is necessary in patients with renal impairment.
Side Effects
- Nephrotoxicity: Risk of kidney damage, especially with higher doses or prolonged use.
- Ototoxicity: Hearing loss, particularly with high serum levels.
- Red man syndrome: A hypersensitivity reaction characterized by flushing, rash, and hypotension, often due to rapid infusion. Can be mitigated by slowing the infusion rate and pre-treating with antihistamines.
- Thrombophlebitis: Inflammation of the vein occurring at the injection site.
Monitoring
- Therapeutic drug monitoring (TDM): Serum vancomycin levels are often monitored to ensure efficacy and minimize toxicity. Trough levels are typically measured just before the next dose.
Resistance
- Vancomycin-resistant Enterococci (VRE): Some Enterococcus species have developed resistance to vancomycin.
- Vancomycin-intermediate Staphylococcus aureus (VISA) and vancomycin-resistant Staphylococcus aureus (VRSA): Rare but concerning resistance patterns in S. aureus.
Important Considerations
- Dosing: Must be carefully adjusted based on renal function.
- Infusion rate: Should be administered slowly to avoid red man syndrome.
- Drug interactions: Potential interactions with other nephrotoxic drugs (e.g., aminoglycosides) and medications that affect renal function.
Vancomycin remains a critical antibiotic in the treatment of serious Gram-positive infections, particularly those resistant to other treatments. Proper use and monitoring are essential to maximize efficacy and minimize adverse effects.