CC Pharm | Vanc

Vancomycin (Vancocin) 80/20 Clinical Summary

1. Core Profile & Mechanism

• Class/Action: Glycopeptide bactericidal antibiotic.
• Mechanism: Binds D-alanyl-D-alanine terminus of peptidoglycan precursors. This inhibits cell-wall synthesis (peptidoglycan polymerase and transpeptidation) and alters permeability, leading to cell death. Also inhibits RNA synthesis.
• Spectrum: Gram-positive pathogens only (Staphylococci, Streptococci, Enterococci). Killing is concentration-independent, requiring an AUC/MIC ratio ≥ 400 for efficacy.

2. Therapeutic Uses & Route Dichotomy

• IV Therapy: Septicemia, endocarditis, skin/skin structure, bone/joint, lower respiratory infections, and surgical prophylaxis.
• Oral Therapy: Strictly for C. difficile-associated diarrhea (CDAD) and S. aureus enterocolitis.
• Route Dichotomy: Oral bioavailability is extremely low. Oral doses are excreted in feces and cannot treat systemic infections. Oral is strictly for local GI action; IV is strictly for systemic infections.

3. Administration & Reconstitution

• IV Infusion Rate: Infuse over ≥ 1 hour (10–15 mg/min) to prevent infusion reactions. Loading doses require 2–3 hours.
• Dilution: Reconstituted vials are diluted with compatible fluids (e.g., D5W, 0.9% NaCl) to 5 mg/mL (up to 10 mg/mL for fluid restriction). Higher concentrations increase reaction risk.
• Oral Solutions: Injection vials can be compounded in water/syrup for enteral/nasogastric use.
• Unlabeled Routes: Rectal enemas for CDAD with ileus; preservative-free intrathecal/intraventricular injections for CNS infections.

4. Adverse Effects & Interactions

• Complications: Nephrotoxicity (renal failure), ototoxicity (hearing loss, tinnitus, vertigo), neutropenia, thrombocytopenia, SJS/TEN, DRESS, and anaphylactoid reactions.
• Infusion Reaction: Rapid IV infusion causes histamine release, leading to hypotension, dyspnea, flushing, pruritus, and urticaria. Manage by stopping or slowing the infusion.
• Interactions: Synergistic toxicity with aminoglycosides. Histamine-inducing drugs (ciprofloxacin, opioids, propofol) can hinder desensitization.

5. Monitoring & Interventions (The "20%" Core)

• Therapeutic Drug Monitoring (TDM): Mandatory for IV therapy. Trough levels of 15–20 mg/L target a therapeutic AUC/MIC of 400–600.
• Renal Adjustments: Extend IV intervals in renal impairment based on CrCl or SCr to avoid drug accumulation.
• Key Interventions: Monitor renal function (SCr, BUN), urine output, and auditory symptoms. Assess IV site frequently for phlebitis.