Factors Influencing Accurate Medication Dosing

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Compared with pharmacy students, the general population was less likely to break tablets into equal parts.
Compared with pharmacy students, the general population was less likely to break tablets into equal parts.

A new study published in the Journal of Pharmacy and Pharmacology sought to determine factors that influence accurate tablet splitting and liquid dosing by patients as compared with healthcare professionals.1

Medication modification (MM) was assessed among 85 volunteers from the general public and 73 students enrolled in the Master of Pharmacy program at the University of Australia (UWA). Four different sized placebo tablets were weighed after being split – by hand or using a tablet splitter – by a total of 88 participants. For liquid medications, 85 participants used a syringe or a dosing cup to measure 5 mL of water, 0.5% methylcellulose (MC), and 1% MC.

Compared with pharmacy students, the general population was less likely to break tablets into equal parts; age, gender and previous experience were considered insignificant factors. Results showed that when all tablets were considered, the negative percentage deviation from the half-tablet weight (DA) had a median value of 7.35% and a maximum value of 83.85%. The positive DA had a median value of 7.19% and a maximum value of 66.18%.  The general population had significantly greater DA compared to the pharmacy students (<.0001).  

When the tablets were scored, the DA was significantly lower compared with the same sized unscored tablets (=.0003). The use of a tablet splitter provided greater accuracy than hand splitting; scored tablets also split more equally than unscored tablets. More than 25% of the small scored tablets could not be split by hand, and approximately 41% of the large tablets, which were not scored, were split into more than 2 portions by the tablet splitter.

The percent deviation (PercDev) was measured to test accuracy from expected volumes in the liquid medications. Results showed that the syringe gave rise to smaller PercDev for all 3 liquids measured compared to the dosing cup. In addition, while the higher-viscosity MC liquids were measured with greater accuracy when using the syringe, with the dosing cup, the accuracy decreased with increasing liquid viscosity.

The authors conclude that pharmacists can significantly "enhance the accuracy of these measurements by supplying an oral syringe rather than a dosing cup." For splitting tablets, manufacturers may help accuracy by providing, "appropriate tablet size, and possibly shape, and a score line in the tablet, particularly for tablets of drugs with narrow therapeutic indices."

The authors also advised that further studies into medical modification should also examine the clinical responses to the split tablets of potent medication.

 

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Reference

  1. Abu-geras D, Hadziomerovic D, Leau A, et al. Accuracy of tablet splitting and liquid measurements: an examination of who, what and how.  [published online December 28, 2017] J Pharm Pharmacol. doi: 10.1111/jphp.12671
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