Accuracy of enteral syringes with commonly prescribed paediatric liquid medicines

Abstract

To investigate the paediatric volumetric accuracy for two enteral syringe brands, using commercially available liquid drug formulations, across a range of clinically relevant volumes and physicochemical properties. Method:In vitro experiment under laboratory conditions. Ten drug formulations were tested for two syringe brands (Baxa, Medicina) using a range of formulation volumes (0.05 to 5 mL) and syringe sizes (1 to 5 mL). The weight of syringes, empty, filled and after expelling liquids were accurately measured and converted into volume, based on the known formulation densities. Ten replications were performed for each combination of drug, syringe and volume. Accuracy of the delivered volume was expressed as a percentage of desired volume, with desired range being within +10% for all replications. Results:The two brands showed a different type of error, with Baxa demonstrating a slight positive bias (excess average volume delivered) at the smallest volumes tested in each syringe size, while Medicina had poorer precision (greater variability) at the smaller volumes (ANOVA 2-and 3-way interactions all P< 0.005). Using these results we were able to identify a lower limit for volume accuracy for each syringe size and each brand. Of note, the 1mL syringe for both brands was inaccurate below volumes of 0.25 mL. The physicochemical properties of pH (range 2.82 to 7.45), surface tension (30.2 to 86.7 mN/m) and viscosity (2 to 299 mPaS) did not influence error in a discernible pattern. Conclusion:Volumetric dosing was inaccurate when the smallest volumes were used across all syringe sizes and brands. These volumes reflect those used in clinical practice; thus error could potentially be reduced by manufacturers revising formulation concentrations for certain drugs.3

European Paediatric Formulation Initiative workshop report: Improving the administration of oral liquid medicines in paediatrics using dosing syringes and enteral accessories

“…Healthcare professional perspectives Some of the challenges faced when administering oral liquid medicines to children with enteral syringes have been illustrated through recent research [16]. In this study, a comparison of generic oral dosing syringe brands indicated differences in dosing accuracy across brands and size of syringes, and those with a wide tip (female design) showed a greater dead space volume compared to those with a narrow tip (male design) across each syringe size (Figure 1).…”

“…Oral dosing syringes are considered to be more accurate for delivering small liquid volumes compared to other oral dosing devices [10,11,18,24]. As discussed during the workshop, syringe size and design as well as the physical properties of the oral liquid itself may have an impact on dosing accuracy [16]. Indeed, correct oral (into the mouth) dosing using enteral syringes (female tips) can be challenging and prone to error, especially when the design of the drug product bottle is such that additional accessories such as a bottle adaptor and/or medicine straw are required.…”

Evaluation of the practice of dose-rounding in paediatrics

“…Different syringes have different graduation markings. DV accuracy depends on the graduation markings and measurement volume . Parameters were calculated (Box 1 ).…”

“…Measuring calculated doses precisely from liquid formulations can be difficult. Recommended devices, for example oral syringes, may not measure sufficiently accurately, especially when small volumes of liquids are needed …”

Dosing Accuracy of Oral Extemporaneous Suspensions of Antibiotics: Measuring Procedures and Administration Devices

“…The drug efficacy and effectiveness depend on the administration of the correct dose. Thereby, the safe and effective use of antibiotics in liquid oral suspension includes the correct reconstitution, concentration, 'shake before use' procedure, dose measurement, duration of treatment, and storage conditions [6,7].…”