Pharmacists should caution fellow healthcare providers about the potential dangers of tablet splitting, according to a new study. The researchers found that this common practice results in wide dose deviations, which could have serious clinical consequences for tablets that have a narrow margin between therapeutic and toxic doses.
The study, published in the January issue of the Journal of Advanced Nursing, showed that nearly a third of the split fragments deviated from recommended dosages by 15% or more.
In the study by Charlotte Verrue and fellow researchers from the Faculty of Pharmaceutical Sciences, Ghent University, Belgium, five volunteers (a pharmacy student, a researcher, a professor, an administrative worker and a laboratory technician) were asked to split eight different-sized tablets using three commonly used techniques.
Between them the volunteers split tablets into 3600 separate quarters or halves using a splitting device, scissors, or a kitchen knife. After splitting, each fragment was weighed to see how much it deviated from the theoretical weight.
The researchers found that 31% of the tablet fragments deviated from their theoretical weight by more than 15%, and 14% deviated by more than 25%. Even with use of a splitting device, the most accurate method, error margins were 21% and 8%, respectively.
Key results included:
· Using a splitting device was the most accurate method. Nonetheless, it resulted in a 15% to 25% error margin in 13% of cases; this was lower than the 22% for the scissors and 17% for the knife.
· The splitting device produced a deviation of more than 25% in 8% of cases, compared with 19% for the scissors and 17% for the knife.
· Some drugs were much easier to split accurately than others. The easiest to split produced an overall error margin (15% deviation or more) of 2% and the most difficult tablets produced an error margin of 19%.
The authors recommend use of a splitting device when splitting cannot be avoided, for example when the prescribed dose is not commercially available or where there is no alternative formulation, such as a liquid. They also advise that staff members responsible for splitting tablets should receive training to enable them to split as accurately as possible and that they should be made aware of the possible clinical consequences of dose deviations. Finally, they call for drug manufacturers to introduce a wider range of tablet doses or liquid formulations to avoid the need for tablet splitting.