Belgian scientists have raised concerns about the common practice of 'tablet splitting', whereby patients or nursing home staff cut pills into smaller pieces to make them easier to swallow.
According to scientists, the practice is widespread but may significantly affect the dose patients receive.
Researchers at Ghent University carried out a small study in which five volunteers were asked to split eight tablets of different sizes and shapes, including medicines for Parkinson's disease, heart failure and arthritis.
Participants used three different methods to split their pills - a splitting device, scissors or manual spitting for scored tablets, and a kitchen knife.
The whole tablets were weighed prior to splitting and these figures were compared to the weights of their individual parts after they had been divided up.
The researchers found that for all tablets, methods two and three resulted in much higher weight losses than the splitting device.
Overall, 31 per cent of tablets that were split differed from the recommended dose by at least 15 per cent, with some deviating by more than 25 per cent.
Writing in the Journal of Advanced Nursing, the study authors warned that splitting tablets can lead to "large dose deviations or weight losses" and that this "could have serious clinical consequences for medications with a narrow therapeutic-toxic range".
They concluded: "On the basis of the results in this report, we recommend use of a splitting device when splitting cannot be avoided."
Source Athritis Support