Objective Oral syringes are the preferred method for delivering paediatric enteral drugs; however, little is known about factors affecting accuracy, particularly at volumes <5 mL. We investigated volumetric accuracy for enteral syringes, using commercially available liquid drug formulations with various physicochemical properties at clinically relevant volumes.

Design In vitro experiment.

Interventions Ten drugs were tested using two syringe brands (Baxa, Medicina) across a range of formulation volumes (0.05–5 mL) and syringe sizes (1–5 mL). Syringe weights (empty and filled) were converted into volume, using known formulation densities. Ten replications were performed for each drug/syringe/volume combination.

Main outcome measures Delivered volume accuracy was expressed as a percentage of intended volume, with the desired range being within ±10%.

Results Baxa demonstrated a slight positive bias (excess average volumes delivered) at the smallest volumes for each syringe size, while Medicina had poorer precision (greater variability, analysis of variance–interactions all p<0.005). From these results, we identified the limit for volume accuracy for each syringe size and brand. Of note, the 1 mL syringe for both brands was inaccurate for delivering volumes ≤0.1 mL. The physicochemical properties of pH (range 2.82–7.45), surface tension (30.2–86.7 mN/m) and viscosity (2–299 mPaS) did not influence error in a discernible pattern.

Conclusions Dosing was inaccurate when small volumes were used across all syringe sizes and brands. These reflect volumes used in clinical practice. Administration error could potentially be reduced by (1) clinicians using syringes appropriate to dosing volumes and (2) manufacturers revising formulation concentrations for drugs.