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

References

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU Emergency Medicine Trainee based in Melbourne, Australia. Co-author of the LITFL ECG Library. Likes Ultrasound, Echo, ECGs, and anything and everything with caffeine | Twitter | ECG Library |

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