Medical experts have issued a warning about the common practice of tablet splitting after a study found that a large percentage of split pill fragments can deviate from recommended dosages by up to 25% or more. In a study published in the January issue of the Journal of Advanced Nursing, researchers argued that the practice could have serious clinical consequences for tablets that have a narrow margin between therapeutic and toxic doses.
Researchers from the Faculty of Pharmaceutical Sciences at Ghent University, Belgium, asked five volunteers to split eight different-sized tablets using three techniques commonly used in nursing homes.
They found that 31% of the tablet fragments deviated from their theoretical weight by more than 15%, and that 14% deviated by more than 25%. Even the most accurate method produced error margins of 21% and 8% respectively.
“It is done for a number of reasons: to increase dose flexibility, to make tablets easier to swallow, and to save money for both patients and healthcare providers,” said study lead Dr Charlotte Verrue. “However, the split tablets are often unequal sizes and a substantial amount of the tablet can be lost during splitting.”
With the exception of a technician, none of the study participants had tablet-splitting experience. The authors said this likely replicated nursing home conditions where splitting is not always performed by professional nurses.
Between them they split tablets into 3,600 separate quarters or halves using a splitting device, scissors, and a kitchen knife. The eight different tablets were different shapes and sizes, three were unscored, three had one score line, and the others had two.
The drugs were prescribed for a range of health conditions, including Parkinson's, congestive heart failure, thrombosis, and arthritis.
After splitting, each fragment was weighed to see how much they deviated from the theoretical weight.
Key results included:
· Using a splitting device was the most accurate method. It still produced a 15 to 25% error margin in 13% of cases, but this was lower than the 22% for scissors and the 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%.
“Tablet splitting is daily practice in nursing homes,” Verrue said. “However, not all formulations are suitable for splitting and, even when they are, large dose deviations or weight losses can occur. This could have serious clinical consequences for drugs where there is a small difference between therapeutic and toxic doses.
“Based on our results, we 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.”