Efficacy and safety of continuous infusions with elastomeric pumps for outpatient parenteral antimicrobial therapy (OPAT): an observational study.

Objectives: This study aimed to evaluate the efficacy and safety of continuous antimicrobial infusion using elastomeric pumps in an outpatient setting, while simultaneously documenting circulating antibiotic concentration exposure achieved with this mode of administration. Methods: Clinical outcomes, adverse events and antibiotic plasma concentrations were recorded for all patients treated by continuous infusion with elastomeric pumps at the outpatient parenteral antimicrobial therapy (OPAT) unit of the University Hospital of Lausanne between December 2013 and January 2017. The study was registered under ClinicalTrials.gov identifier NCT03221140. Results: One hundred and fifty outpatients were treated by continuous intravenous infusions using flucloxacillin (70 patients), cefepime (36), vancomycin (32) and piperacillin/tazobactam (12). The calculated free fractions of each antibiotic were above the epidemiological cut-off values for resistance (ECOFF) of the treated microorganisms in 92% of measurements. Cure was achieved in 143 patients (95%) 3 months after the end of treatment. Four patients needed unexpected readmission and three had a relapse. In none of the patients with unsuccessful treatment was the ratio of free antibiotic plasma concentration/ECOFF <1. Sixteen patients (11%) had an adverse event, none of them being of severity grade 4 or 5. Conclusions: Continuous infusions of flucloxacillin, cefepime, vancomycin and piperacillin/tazobactam using elastomeric pumps seem to be an effective and safe approach to treat outpatients. The number of treatment successes was very high and adverse events occurred at a similar rate as reported by other OPAT centres. The measured antibiotic plasma concentrations confirmed adequate drug concentration exposure for the vast majority of patients.

Adequate plasma drug concentrations suggest that amoxicillin can be administered by continuous infusion using elastomeric pumps.

Background: Elastomeric pumps can be useful for the administration of antibiotics in the outpatient setting. Objectives: To determine amoxicillin degradation in elastomeric pumps, as well as the effectiveness of amoxicillin treatment administered by elastomeric pumps. Methods: Antibiotic degradation was measured in elastomeric pumps filled with 6 g of amoxicillin in 240 mL of NaCl 0.9% by drawing samples at 12 h intervals when stored in the fridge for 48 h and when worn around the waist for 24 h. Subsequently nine patients were treated with continuous infusions of 8 or 12 g of amoxicillin per day. Plasma amoxicillin concentrations were measured on each visit to the outpatient parenteral antibiotic therapy unit. Clinical outcome was verified 3 months after the end of treatment. Results: Amoxicillin degradation in elastomeric pumps reached 10% after 48 h in the fridge and an additional 30% when worn around the waist for 24 h. Mean plasma drug concentrations achieved with 12 g of amoxicillin per day were 18.5 mg/L (95% CI 13.5-23.5), which is largely above the MIC of amoxicillin-susceptible bacteria. Nine patients treated for various complicated infections were cured and had no unexpected adverse effects. Conclusions: Adequate plasma drug concentrations and favourable clinical outcomes suggest that amoxicillin can be administered by continuous infusion using elastomeric pumps. This treatment modality does not fulfil formal requirements regarding pharmaceutical stability, but the resulting safety impact in patients is probably limited. Therapeutic drug monitoring and a close clinical follow-up are recommended if this route of administration is chosen.