Vancomycin

Oral Antibiotics

Drug class: Glycopeptide Antibiotics

Vancomycin (VANCOCIN)（中文：萬古霉素）

Common Strengths

Vancomycin is commonly available in the following strengths:

• Intravenous (IV): 500 mg and 1 g vials
• Oral: 125 mg and 250 mg capsules

Drug Trade Names

Vancocin

Drug Usage

Vancomycin is a glycopeptide antibiotic primarily used to treat severe bacterial infections, particularly those caused by methicillin-resistant Staphylococcus aureus (MRSA).

Vancomycin is indicated for conditions such as:

• septicemia
• endocarditis
• skin infections
• bone infections
• pseudomembranous colitis caused by Clostridium difficile.

Mechanism of Action

Vancomycin works by inhibiting bacterial wall synthesis. It binds to the D-alanyl-D-alanine terminus of cell wall precursors, preventing the incorporation of these precursors into the growing peptidoglycan layer and leading to bacterial cell lysis.

Route of Administration

Vancomycin can be administered:

• Intravenously (IV) for systemic infections
• Orally for specific gastrointestinal infections like C. difficile colitis

Dosages

• Adults: IV: 1 to 1.5 g every 12 hours (elderly >65 years 500 mg every 12 hours or 1 g once daily)
• Child: 15 mg/kg every 8 hours, max. 2 g daily

<Surgical prophylaxis> 1 g for 1 dose

Side Effects

Frequency	Adverse reactions
Common Side Effects	Nausea
	Abdominal pain
	Flushing: Rapid intravenous infusion of vancomycin can lead to flushing, rash, and hypotension
Serious Side Effects	Nephrotoxicity: Acute Kidney Injury especially in elderly patients or those with pre-existing kidney conditions. It manifests as increased serum creatinine levels and decreased urine output.
	Ototoxicity: There is a risk of hearing loss which may present as tinnitus (ringing in the ears) or actual hearing impairment
	Allergic reactions: Serious allergic reactions including symptoms such as hives, difficulty breathing, swelling of the face or throat, and severe skin reactions like Stevens-Johnson syndrome and toxic epidermal necrolysis.
	Blood disorders: Neutropenia (low white blood cell count) and Thrombocytopenia (low platelet counts) which may increase the risk of infections and bleeding.

Pharmacokinetics

• Absorption: Vancomycin has poor oral bioavailability (less than 10%), which limits its effectiveness when taken orally for systemic infections.
• Metabolism and Elimination: Vancomycin is not significantly metabolized; about 75-80% of the drug is excreted unchanged in the urine within the first 24 hours.
• Half-life: The elimination half-life in patients with normal renal function typically ranges from 4 to 11 hours, with an average of about 6 hours. In patients with renal impairment, this half-life can extend to several days, necessitating careful monitoring and dose adjustments
• Onset Time: The onset o action for intravenous vancomycin is rapid, with peak serum concentrations achieved immediately following the completion of the infusion. For oral vancomycin, the onset time is less clearly defined but is generally slower due to poor absorption.
• Duration of Action: The therapeutic effects of vancomycin can typically be observed within 48 to 72 hours after starting treatment. The duration of therapy depends on the type and severity of the infection; for instance, staphylococcal endocarditis may require prolonged treatment lasting three weeks or more.

Drug Precautions

Pregnancy

Use only if needed; potential risk should be weighed against benefits.

Breastfeeding

Present in milk; weigh potential risks against benefits.

Children and Elderly

Safety established in children. Elderly patients may require dose adjustments due to age-related renal function decline.

Drug Monitoring Items

• Due to its narrow therapeutic index, careful monitoring of vancomycin levels is crucial to ensure efficacy while minimizing toxicity, particularly nephrotoxicity.
• Serum creatinine levels

Drug Interactions

• Caution with nephrotoxic agents, such as
  • Aminoglycosides (e.g. gentamicin, amikacin): Increased risk of kidney damage.
  • Loop diuretics (e.g. furosemide): Increased risk of kidney damage.
  • NSAIDs (e.g. ibuprofen): Potential for enhanced nephrotoxic effects.
  • Anticoagulants (e.g. warfarin): There is a theoretical risk of increased bleeding.
  • Anesthetic agents: May lead to cardiovascular and respiratory complications when used with vancomycin.

FAQ

What Should I Avoid while Taking?

Avoid other nephrotoxic medications unless advised by a healthcare provider.