Outpatient parenteral antibiotic therapy

Outpatient parenteral antibiotic therapy (OPAT) is used to administer non-oral antibiotics (usually intravenously) without the need for ongoing hospitalisation. OPAT is particularly useful for people who are not severely ill but do require a prolonged course of treatment that cannot be given in oral form.^[1] OPAT is being increasingly adopted as part of antimicrobial stewardship programs; it can reduce length of stay, costs and adverse events while improving quality of life.^[2] In a six-year real-world retrospective study conducted at an Italian tertiary-care center, OPAT allowed a relative cost reduction of about 92% and an average daily cost of €32 for OPAT versus €400 for inpatient therapy.^[3] OPAT can be administered in an outpatient facility (including a provider's office, infusion center or day hospital) or at a patient's residence using an infusion pump, such as an elastomeric pump.^[4][5]

Although OPAT is traditionally based on intravenous administration, the subcutaneous route has emerged as a pragmatic alternative in selected clinical settings. Several antibiotics, including β-lactams (most commonly ceftriaxone) and glycopeptides (teicoplanin), are administered subcutaneously (off-label) in outpatient and home-care contexts. Available clinical and pharmacokinetic data suggest that subcutaneous administration may achieve adequate drug exposure and clinical effectiveness when appropriate dosing and loading strategies are applied.^[6]

Common antimicrobials used for continuous infusion are shown below:^[7]

Before starting beta-lactams and vancomycin infusion, it is advisable to administer a loading dose in order to reduce time to reach target concentrations^[8][9]