Antibiotic IV to PO Switch 💊

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💡 Overview

  • Switching from IV to oral antibiotics when appropriate improves patient care and reduces costs.
  • Consider switch when patient is clinically stable, able to take oral medications, and has good GI absorption.
  • Always review bioavailability, drug interactions, and patient-specific factors before switching.
  • Based on HSE AMRIC guidelines for antimicrobial stewardship and IV to oral switch protocols.

✅ Switch Criteria

  • Patient clinically stable with improving vital signs
  • Able to take oral medications (no vomiting, good GI function)
  • Good oral bioavailability of the chosen antibiotic
  • No significant drug interactions or absorption issues
  • Patient compliance with oral regimen can be ensured

⚠️ Important Considerations

  • Doses are for normal renal and hepatic function - adjust as needed
  • Oral bioavailability may differ between tablets/capsules and suspensions
  • Some antibiotics must be taken on empty stomach for optimal absorption
  • Review drug and food interactions before prescribing
  • Consider severity of infection when determining appropriate dosing
  • Consult pharmacy or microbiology for complex cases

📋 Common Switch Patterns

  • Same dose: Amoxicillin, clarithromycin, levofloxacin, linezolid
  • Reduced dose: Clindamycin (300-450mg vs 600mg-1.2g), flucloxacillin (500mg-1g vs 1-2g)
  • Different drug: Benzylpenicillin → Amoxicillin or Phenoxymethylpenicillin
  • Not recommended: Cefuroxime, ceftriaxone, piperacillin-tazobactam (poor oral bioavailability)
  • Special considerations: Ciprofloxacin (avoid with enteral nutrition), metronidazole (slightly reduced dose)

Antibiotic IV to PO Switch

Recommended oral agents when switching from IV to oral antimicrobials

Important Notes:

  • Doses included are for normal renal & hepatic function
  • Doses are for oral capsules/tablets unless otherwise specified
  • Review drug and food interactions. Some antimicrobials need to be taken on an empty stomach
  • Doses may need to be adjusted according to severity of infection
  • See Eolas Medical/BNF/SmPC or seek pharmacist advice regarding dose adjustments
  • Based on HSE AMRIC guidelines for antimicrobial stewardship and IV to oral switch protocols
Amoxicillin
Switch Available
IV Dose:500mg – 1g q8h (max 12g/day IV)
Oral Switch:500mg – 1g q8h
Notes: Same dose for oral switch
Benzylpenicillin
Switch Available
IV Dose:1.2g-2.4g q4-6h
Oral Switch:Amoxicillin 500mg – 1g q8h (preferred) OR Phenoxymethylpenicillin: 666mg q6h (Calvepen®) OR 500mg q6h (Kopen®)
Notes: Switch to amoxicillin or phenoxymethylpenicillin
Cefuroxime
Not advised
IV Dose:750mg-1.5g q8h
Oral Switch:Not advised
Notes: Poor oral bioavailability. Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist
Ceftriaxone
No direct alternative
IV Dose:2g q12h/24h
Oral Switch:No direct alternative
Notes: Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist
Ciprofloxacin
Switch Available
IV Dose:400mg q8-12h
Oral Switch:500mg-750mg q12h
Notes: If on enteral nutrition, IV ciprofloxacin preferable to oral as bioavailability may be decreased
Clarithromycin
Switch Available
IV Dose:500mg q12h
Oral Switch:500mg q12h
Notes: Same dose for oral switch
Clindamycin
Switch Available
IV Dose:600mg – 1.2g q6h
Oral Switch:300mg - 450mg q6h
Notes: Reduced dose for oral administration
Co-amoxiclav
Switch Available
IV Dose:1.2g q8h
Oral Switch:500mg/125mg (625mg) – 875mg/125mg (1g) q8h
Notes: For 875mg/125mg (1g) q8h please prescribe as 875mg/125mg q8h
Co-trimoxazole
Switch Available
IV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Flucloxacillin
Switch Available
IV Dose:1-2g q6h
Oral Switch:500mg - 1g q6h
Notes: Reduced dose for oral administration
Fluconazole
Switch Available
IV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Isavuconazole
Switch Available
IV Dose:200mg q8h for 48h, then 200mg q24h
Oral Switch:Same dose
Notes: Same dose for oral switch
Levofloxacin
Switch Available
IV Dose:500mg q12h/24h
Oral Switch:Same dose
Notes: Same dose for oral switch
Linezolid
Switch Available
IV Dose:600mg q12h
Oral Switch:Same dose
Notes: Same dose for oral switch
Metronidazole
Switch Available
IV Dose:500mg q8h
Oral Switch:400mg q8h
Notes: Slightly reduced dose for oral administration
Piperacillin-tazobactam
No direct alternative
IV Dose:4.5g q8h/6h
Oral Switch:No direct alternative
Notes: Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist
Rifampicin
Switch Available
IV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Voriconazole
Switch Available
IV Dose:6mg/kg q12h for 24h, then 4mg/kg q12h
Oral Switch:Patients >40kg: 400mg q12h for 2 doses (if loading required) then 200mg q12h
Notes: Dose may be adjusted based on therapeutic drug monitoring results

References:

HSE AMRIC:Intravenous to Oral Switch Toolkit (February 2025)

This table is based on the official HSE AMRIC guidelines for antimicrobial stewardship and IV to oral switch protocols.

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