Antibiotic IV to PO Switch 💊
Reference table for switching from intravenous to oral antimicrobials. Includes dosing conversions, bioavailability considerations, and clinical notes based on HSE AMRIC guidelines.
💡 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
| IV Antimicrobial | IV Dose | Oral Switch Option/Dose | Notes |
|---|---|---|---|
| Amoxicillin | 500mg – 1g q8h (max 12g/day IV) | 500mg – 1g q8h | Same dose for oral switch |
| Benzylpenicillin | 1.2g-2.4g q4-6h | Amoxicillin 500mg – 1g q8h (preferred) OR Phenoxymethylpenicillin: 666mg q6h (Calvepen®) OR 500mg q6h (Kopen®) | Switch to amoxicillin or phenoxymethylpenicillin |
| Cefuroxime | 750mg-1.5g q8h | Not advised | Poor oral bioavailability. Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist |
| Ceftriaxone | 2g q12h/24h | No direct alternative | Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist |
| Ciprofloxacin | 400mg q8-12h | 500mg-750mg q12h | If on enteral nutrition, IV ciprofloxacin preferable to oral as bioavailability may be decreased |
| Clarithromycin | 500mg q12h | 500mg q12h | Same dose for oral switch |
| Clindamycin | 600mg – 1.2g q6h | 300mg - 450mg q6h | Reduced dose for oral administration |
| Co-amoxiclav | 1.2g q8h | 500mg/125mg (625mg) – 875mg/125mg (1g) q8h | For 875mg/125mg (1g) q8h please prescribe as 875mg/125mg q8h |
| Co-trimoxazole | Indication specific | Same dose | Dose depends on indication |
| Flucloxacillin | 1-2g q6h | 500mg - 1g q6h | Reduced dose for oral administration |
| Fluconazole | Indication specific | Same dose | Dose depends on indication |
| Isavuconazole | 200mg q8h for 48h, then 200mg q24h | Same dose | Same dose for oral switch |
| Levofloxacin | 500mg q12h/24h | Same dose | Same dose for oral switch |
| Linezolid | 600mg q12h | Same dose | Same dose for oral switch |
| Metronidazole | 500mg q8h | 400mg q8h | Slightly reduced dose for oral administration |
| Piperacillin-tazobactam | 4.5g q8h/6h | No direct alternative | Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist |
| Rifampicin | Indication specific | Same dose | Dose depends on indication |
| Voriconazole | 6mg/kg q12h for 24h, then 4mg/kg q12h | Patients >40kg: 400mg q12h for 2 doses (if loading required) then 200mg q12h | Dose may be adjusted based on therapeutic drug monitoring results |
Amoxicillin
Switch AvailableIV Dose:500mg – 1g q8h (max 12g/day IV)
Oral Switch:500mg – 1g q8h
Notes: Same dose for oral switch
Benzylpenicillin
Switch AvailableIV 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 advisedIV 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 alternativeIV Dose:2g q12h/24h
Oral Switch:No direct alternative
Notes: Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist
Ciprofloxacin
Switch AvailableIV 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 AvailableIV Dose:500mg q12h
Oral Switch:500mg q12h
Notes: Same dose for oral switch
Clindamycin
Switch AvailableIV Dose:600mg – 1.2g q6h
Oral Switch:300mg - 450mg q6h
Notes: Reduced dose for oral administration
Co-amoxiclav
Switch AvailableIV 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 AvailableIV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Flucloxacillin
Switch AvailableIV Dose:1-2g q6h
Oral Switch:500mg - 1g q6h
Notes: Reduced dose for oral administration
Fluconazole
Switch AvailableIV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Isavuconazole
Switch AvailableIV Dose:200mg q8h for 48h, then 200mg q24h
Oral Switch:Same dose
Notes: Same dose for oral switch
Levofloxacin
Switch AvailableIV Dose:500mg q12h/24h
Oral Switch:Same dose
Notes: Same dose for oral switch
Linezolid
Switch AvailableIV Dose:600mg q12h
Oral Switch:Same dose
Notes: Same dose for oral switch
Metronidazole
Switch AvailableIV Dose:500mg q8h
Oral Switch:400mg q8h
Notes: Slightly reduced dose for oral administration
Piperacillin-tazobactam
No direct alternativeIV Dose:4.5g q8h/6h
Oral Switch:No direct alternative
Notes: Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist
Rifampicin
Switch AvailableIV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Voriconazole
Switch AvailableIV 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.