Intravenous (IV) to oral antimicrobial switch

Initially, giving antimicrobials by the intravenous (IV) route may be preferable in severe infection.

Most patients who are clinically improved and adequately absorb oral medications, administration can be switched to the oral route after 48 hours of IV therapy. This is known as the IV to oral switch.

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The oral route of administration for antimicrobials is preferred to the IV route wherever possible as oral administration is associated with:

  • Decreased risk of infection from IV lines
  • Decreased risk of thrombophlebitis
  • Significantly less cost than IV therapy
  • Reduction in hidden costs (diluents, equipment, needles, nursing time)
  • More patient friendly
  • May lead to earlier discharge.

A recent paediatric study found that patients who commenced on oral antibiotics had a mean shorter length of stay in hospital, compared to patients commenced on IV antibiotics.

Patients should be reviewed at 24 to 48 hours. The following criteria are helpful when deciding if oral therapy is appropriate:

  • Antibiotic treatment is still indicated
  • Oral fluids/foods are tolerated and no reason to believe that poor oral absorption may be a problem (e.g. vomiting, diarrhoea, short gut syndrome, active gastro-intestinal bleeding)
  • Temperature less than 37.5°C for 24 to 48 hours
  • No signs of sepsis
  • An appropriate oral antibiotic is available
  • Extra high tissue antibiotic concentrations or a prolonged course of IV antibiotics are not essential.
  • Hospital acquired infections.
  • Intra-abdominal infections.
  • Pneumonia.
  • Skin and soft tissue infections.
  • Cervical lymphadenopathy.
  • Sinusitis.
  • Urinary tract infections.
  • Some gram positive blood stream infections
Some conditions require a prolonged course of intravenous antibiotics or very high tissue concentrations. Early IV to oral switch is not considered appropriate in the following conditions:

  • Bacterial meningitis.
  • Gram negative blood stream infections.
  • S. aureus blood stream infections
  • Central Nervous System (CNS) infections.
  • Cystic fibrosis.
  • Deep abscesses.
  • Endocarditis or intravascular infection.
  • Central venous device infection.
  • Necrotising enterocolitis.
  • Immunosuppressed patients (may be considered on advice of Paediatric ID team).
  • Malabsorption, severe diarrhoea and/or uncontrolled nausea and vomiting.
  • Neonate (not an absolute contraindication, discuss with Paediatric ID team).
Please refer to CHQ Antimicrobial prescribing guidelines for dosing in specific indications. If no equivalent oral formulation available, the choice of antimicrobial should be based on advice from Paediatric ID specialist.
Table 1: Suitable IV to oral drug switches