Leftover of amoxicillin suspension after use by children in the Netherlands

Background: Amoxicillin (+/- clavulanic acid) suspension is commercially available in the Netherlands in certain strengths (25mg/ml, 50mg/ml and 100mg/ml) and volumes (30 ml and 100ml). This can cause a mismatch between the amount that is prescribed by the physician and the amount that is dispensed to the patient by the pharmacy. The consequence of this mismatch can be a leftover and thus a waste of amoxicillin suspension.

Objectives: To quantify leftover of amoxicillin suspension after use by children, addressing potential disparities between physician-prescribed and pharmacy-dispensed amounts.

Methods: We performed a retrospective cohort study including amoxicillin suspension dispensations for patients aged 0-12 years between 2017-2019 utilizing the Dutch PHARMO database. Leftover amount of amoxicillin was estimated by assessing the disparity between the prescribed and dispensed amounts. Extrapolated amoxicillin weight and economic spillage estimates for the Netherlands were determined. The impact of two theoretical interventions on leftover amount was assessed: 1) introducing a vial with half the volume of the current vials, and 2) a combination of the first intervention with a maximum of 10% round-down by the dispensing pharmacy of the prescribed dose.

Results: We included 79,512 amoxicillin suspension dispensations for 62,252 patients. The average leftover amount of amoxicillin suspension per dispensing was 27%. The yearly amount of amoxicillin leftover was 49.8 kg in the study cohort, equivalent to yearly 633 kg and €621,000 when extrapolated to the Netherlands. Employing the first theoretical intervention reduced the average leftover per dispensing to 20%, reducing the yearly leftover to 31.6 kg amoxicillin in the study cohort, and to 400 kg and €400,000 extrapolated. The second theoretical intervention further reduced leftover to 17%, reducing the yearly leftover to 24.3 kg amoxicillin in the study cohort, and to 300 kg and €300,000 extrapolated.

Conclusions: Approximately a quarter of amoxicillin suspension remains as leftover per dispensing. Applying different theoretical intervention shows the potential for a significant reduction of amoxicillin leftover.