Pharm 101: Vancomycin
Class
Glycopeptide antibiotic
Pharmacodynamics
- Bactericidal antibiotic that inhibits cell wall synthesis by binding to peptidoglycan pentapeptide
- This inhibitions transglycosylase, preventing further elongation of peptidoglycan and cross-linking
- Peptidoglycan is weakened, and cell becomes suspcetible to lysis
- Cell membrane also damaged
- Resistance to vancomycin is due to modification of binding site of peptidoglycan
Pharmacokinetics
- Poor oral absorption
- Oral administration is only for treatment of C difficile colitis
- Widely distributed, including adipose tissue
- CSF levels 7-30% of serum concentration in presence of meningeal inflammation
- 90% excreted by glomerular filtration
- Half-life 6 hours
- Accumulation occurs in renal dysfunction
- Half-life extended to 6-10 days in anephric patients
Antimicrobial activity
- Active primarily against Gram-positive bacteria due to large molecular weight and lack of penetration through Gram-negative cell membranes
- Gram positive bacteria:
- Staph, including MRSA, and those producing B-lactamase and those resistance to nafcillin
- Enterococci
- Gram positive anaerobes
- C difficile
- Clinical uses:
- MRSA bacteraemia
- Endocarditis caused by MRSA
- Meningitis caused by penicillin-resistant pneumococcus (in combination with ceftriaxone)
- C difficile colitis (oral administration)
Adverse effects
- Local irritation at site of injection
- “Red man syndrome”
- Infusion-related flushing caused by histamine release
- Fever
- Nephrotoxicity
- Ototoxicity is rare, but risk is increased with co-administration of another ototoxic drug such as an aminoglycoside
Precautions/contraindications
- Dose adjustment required in renal impairment, morbid obesity
Further reading
- Buttner R. Pharm 101: Gentamicin. LITFL
References
- Katzung BG. Basic and Clinical Pharmacology. 14e. 2018: 807-809, 812
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Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Co-creator of the LITFL ECG Library. Twitter: @rob_buttner