Mechanism of Action

Glycopeptide antibiotic, bactericidal against GRAM-POSITIVE organisms only. It binds the D-alanyl-D-alanine terminus of peptidoglycan precursors, blocking cell-wall cross-linking. Route dictates the indication: IV vancomycin treats systemic MRSA (it is NOT absorbed from the gut), while ORAL vancomycin stays in the gut lumen and is therefore the agent for C. difficile colitis. Trough-guided dosing (target 15–20 mcg/mL for serious infection) balances bactericidal effect against nephrotoxicity.

15 (serious-infection target floor)

Sub-therapeutic

Therapeutic trough

Nephrotoxicity risk

mcg/mL

Common Medications

vancomycinPrototype

single high-yield glycopeptide

Indications

MRSA bacteremia

IV; also endocarditis, osteomyelitis, pneumonia

serious gram-positive infection

IV; drug of choice for serious MRSA

Clostridioides difficile colitis

ORAL — stays in the gut lumen

Side Effects

phlebitis at IV site

infuse via good access; cannot be given IM (tissue necrosis)

transient flushing with slow infusion

rate-related histamine release

Contraindications & Interactions

Contraindications

intramuscular route

causes severe tissue necrosis — IV or oral only

rapid IV infusion

triggers Red Man Syndrome; infuse ≥ 60 min

Interactions

aminoglycosides

additive nephrotoxicity and ototoxicity

NSAIDs

additive nephrotoxicity

IV contrast

additive nephrotoxicity

Administration & Monitoring

infuse over at least 60 minutes

longer for doses > 1 g; never speed up on early tolerance

draw trough 30 min before the next dose10–20 mcg/mL

at steady state (before 4th–5th dose); NOT a peak/after infusion

monitor BUN and creatinine

baseline and throughout — nephrotoxic

assess hearing

ask about tinnitus / hearing changes

hold and notify if supratherapeuticHold

level above target or AUC over range

ensure adequate hydration

renal protection

premedicate diphenhydramine if prior RMS

and extend infusion time

Patient Teaching

report flushing or itching during infusion

Red Man Syndrome — the drip is too fast

report ringing in the ears or hearing changes

ototoxicity may be permanent

report decreased urination

nephrotoxicity

take oral vancomycin exactly as prescribed

for C. diff — finish the full course

stay well hydrated

Report Nowescalate immediately

Red Man Syndrome Hallmark

rate-related histamine reaction (NOT allergy): flushing/erythema of face-neck-upper torso, pruritus, hypotension; pause infusion, give diphenhydramine, restart slower

nephrotoxicitytrough > 20 mcg/mL

rising creatinine, falling urine output; risk climbs above trough 20

ototoxicity

tinnitus, hearing loss, vertigo — may be IRREVERSIBLE; report any auditory complaint

anaphylaxis

TRUE allergy — urticaria, wheals, bronchospasm, angioedema; worsens regardless of rate; needs epinephrine (distinguish from RMS)

Clinical Pearl

Red Man = Rate Man: slow the drip and the red goes away — it's histamine, not allergy (true anaphylaxis brings wheals + wheezing and worsens no matter the rate). And mouth for the gut, vein for the body: ORAL vancomycin for C. diff, IV for systemic MRSA. Trough 10–20 mcg/mL drawn 30 min before the next dose.