IV to PO Step-Down
IV to PO

IV to PO

IV to PO Antimicrobial Conversion

  • IV dose: 250 or 500 mg q24h
  • PO drug/dose/interval:
    • Azithromycin 250 mg once daily (requires special authorization under PEI Pharmacare) OR
    • Clarithromycin 500 mg BID (dose adjustment required in renal impairment)
  • Oral Bioavailability:
    • Azithromycin - 37% (lower bioavailability but high tissue penetration)
    • Clarithromycin - 50% (lower bioavailability but high tissue penetration)
  • IV dose: 1000 or 2000 mg q8h
  • PO drug/dose/interval:
    • Cephalexin 500 mg QID
    • Cefadroxil 500 mg BID
  • Oral Bioavailability:
    • Cephalexin - 90%
    • Cefadroxil - 90%

Note: Cephalexin & Cefadroxil

  • Dose adjustment required in renal impairment
  • Assess for true penicillin allergy – cross reactivity exists
  • Consider double dose (1000 mg) at same dosing frequency for severe infections and/or weight >100 kg
  • IV dose: 400 mg q12h or q24h
  • PO drug/dose/interval:
    • Ciprofloxacin 500 mg q12h or q24h (Dose adjustment required in renal impairment)
  • Oral Bioavailability: 70%

  • IV dose: 400 mg q8h
  • PO drug/dose/interval:
    • Ciprofloxacin 750 mg BID (Dose adjustment required in renal impairment)
  • Oral Bioavailability: 70%
  • IV dose: 600-900 mg q8h or q12h
  • PO drug/dose/interval: Clindamycin 300-450 mg QID
  • Oral Bioavailability: 90%
  • IV dose: 500 mg q8h or q12h
  • PO drug/dose/interval: Metronidazole 500 mg q8h or q12h
  • Oral Bioavailability: 100%

Do not convert to oral if co-treating C. difficile

  • IV dose: 500 – 750 mg q24h
  • PO drug/dose/interval: Levofloxacin 500 - 750 mg q24h (Dose adjustment required in renal impairment)
  • Oral Bioavailability: 99%
  • IV dose: 400 mg q24h
  • PO drug/dose/interval: Moxifloxacin 400 mg once daily
  • Oral Bioavailability: 89%
  • IV dose: 400 mg q24h
  • PO drug/dose/interval: Fluconazole 400 mg once daily (Dose adjustment required in renal impairment)
  • Oral Bioavailability: 90%