Accuracy of tablet splitting and liquid measurements: an examination of who, what and how

Objective: To examine factors that might affect the ability of patients to accurately halve tablets or measure a 5-ml liquid dose.

Methods: Eighty-eight participants split four different placebo tablets by hand and using a tablet splitter, while 85 participants measured 5 ml of water, 0.5% methylcellulose (MC) and 1% MC using a syringe and dosing cup. Accuracy of manipulation was determined by mass measurements.

Key findings: The general population was less able than pharmacy students to break tablets into equal parts, although age, gender and prior experience were insignificant factors. Greater accuracy of tablet halving was observed with tablet splitter, with scored tablets split more equally than unscored tablets. Tablet size did not affect the accuracy of splitting. However, >25% of small scored tablets failed to be split by hand, and 41% of large unscored tablets were split into >2 portions in the tablet splitter. In liquid measurement, the syringe provided more accurate volume measurements than the dosing cup, with higher accuracy observed for the more viscous MC solutions than water.

Conclusion: Formulation characteristics and manipulation technique have greater influences on the accuracy of medication modification and should be considered in off-label drug use in vulnerable populations.