IV to Oral Switch Therapy

It is not necessary to treat every infection with parenteral antimicrobial agents. Even where initial therapy with parenteral agents is necessary it may be possible to switch to oral antimicrobial agents after 24 to 48 hours if the patient is responding well to treatment. Switching to oral therapy has advantages for the patient, staff and hospital.

Table 1: IV to Oral Switch Criteria

Table 1: IV to Oral Switch Criteria
In favour of switching	Reasons to avoid/delay switching*
· Clinically improving	· Potential GI absorption problems
· Apyrexial for >24 hours	· Meningitis or CNS infection
· Oral fluids, food & medication tolerated	· Acute osteomyelitis/septic arthritis
· Suitable oral alternative	· Endocarditis
· No reason to avoid/delay switching	· Severe soft tissue infections
I f yes to all ‘In favour of switching’ without any ‘Reasons to avoid/delay switching’ consider switch to oral therapy.	· *Staphylococcus aureus* bacteraemia
	· Inadequately drained abscess
	· Neutropenic sepsis/septic shock
*If in doubt discuss with Microbiology or Infectious Diseases or Pharmacy Some cases may be suitable for IV to PO switch on advice from Micro/ID**

Table 2: Antimicrobials with excellent bioavailability by the oral route

Table 2: Antimicrobials with excellent bioavailability by the oral route

Ciprofloxacin

Clarithromycin

Clindamycin (90%)

Co-trimoxazole

Fluconazole (>90%)

Fusidic Acid/Sodium fusidate (91%)

Levofloxacin (99%)

Linezolid (100%)

Metronidazole (100%)

Posaconazole

Rifampicin

Voriconazole (96%)

Ref: The Sanford Guide to Antimicrobial Therapy Digital update Nov 2024

Table 3: Recommended Oral Agents when Switching from IV to Oral

Table 3: Recommended Oral Agents when Switching from IV to Oral
IV Antibiotic	Oral Option
Amoxicillin 500mg to 1g tds	Amoxicillin 500mg to 1g tds
Benzylpenicillin 1.2g to 2.4g qds	Amoxicillin 500mg to 1g tds OR Phenoxymethylpenicillin 666mg qds
CefTRIAXone	According to indication and culture & sensitivity. Discuss with Microbiology or Infectious Diseases
Cefuroxime 750mg to 1.5g tds + Metronidazole 500mg tds	There is no direct oral alternative; co-amoxiclav 625mg tds may be reasonable if NOT penicillin allergic, according to indication and culture & sensitivity. If penicillin allergic discuss with Microbiology or Infectious Diseases
Ciprofloxacin 400mg bd	Ciprofloxacin 500mg bd
Clarithromycin 500mg bd	Clarithromycin 500mg bd
Clindamycin 600mg to 1.2g qds	Clindamycin 300mg to 450mg qds* *Please discuss switch from IV to oral clindamycin with Micro/ID
Co-amoxiclav 1.2g tds	Co-amoxiclav 625mg-1g tds
Co-trimoxazole	Co-trimoxazole same dose
Flucloxacillin 2g qds	Flucloxacillin 500mg to 1g qds
Fluconazole	Fluconazole same dose
Gentamicin dose per GAPP App calculator	According to indication and culture & sensitivity. Discuss with Microbiology or Infectious Diseases
Levofloxacin	Levofloxacin same dose
Linezolid	Linezolid same dose
Metronidazole 500mg tds	Metronidazole 400mg tds
Piperacillin/tazobactam	There is no direct oral alternative; but oral options may be available according to indication and culture & sensitivity; co-amoxiclav or co-amoxiclav plus ciprofloxacin may be options. Discuss with Microbiology or Infectious Diseases if necessary.
Rifampicin	Rifampicin same dose
Teicoplanin	There is no direct oral alternative but oral options may be available depending on indication and culture & sensitivity data. Discuss with Microbiology or Infectious Diseases.
Vancomycin dose per GAPP App calculator	There is no direct oral alternative but oral options may be available depending on indication and culture & sensitivity data. Discuss with Microbiology or Infectious Diseases.