Wrongly Prescribed Half Tablets in a Swiss University Hospital

Background: Prescription of 1/2 tablets is a widespread practice, mainly to achieve dose flexibility and to facilitate swallowing. However, tablet splitting includes several disadvantages, like destruction of galenic formulation, stability problems, and unequal amount of active ingredient that may reduce effectiveness or result in a greater risk of toxicity. Objective: To assess the rate of wrongly prescribed 1/2 tablets in discharge prescriptions at the University Hospital in Basel (UHBS, 600 beds) and to evaluate its consequences for community pharmacists. Setting: Discharge prescriptions written between January 1st and December 31st 2011 and containing the term “1/2” were extracted from the electronic patients’ data management system of the UHBS. Presence of a score line and suitability for splitting were retrieved from two official sources of drug information. Main Outcome Measure: Wrong prescription was assigned for tablets with no score line or not suitable for dose splitting. Results: Of the 36,751 discharge prescriptions that were recorded in 2011 at the UHBS, 3724 (10.1%) contained at least one prescription item with the term “1/2”. The recipient patients were on average 72.9 ± 14.8 years old (median 76 years), 50.9% were women. Of the 4517 analysed items, 49% had a corresponding lower dosage strength available on the market, making splitting unnecessary. Rate of wrongly prescribed 1/2 tablets reached 16.4% (2.8% of all prescriptions) and concerned predominantly unscored tablets. When the lack of information on splitting suitability (5.6%) and on score lines (0.5%) was taken into account, the rate reached 22.4%. Half of all wrong prescriptions could be assigned to 14 different products that were prescribed with an overall rate between 3.1 and 0.2%. Quetiapine (Seroquel?) at all strengths was the most often wrongly prescribed tablet to split (3.1%; no score line), followed by atorvastatin (Sortis?) at all strengths (1.3%; no score line) and oxazepam (Seresta?) 15 mg (1.2%; with decorative score line). Conclusion: Prescribing of 1/2 tablets is common and concerns every 10th discharge prescriptions. It represents a pharmaceutical care issue, since in almost every second case, an identical drug with half the dosage strength is commercially available and a substitution could be offered by the community pharmacist. Further, one out of 5 prescribed 1/2 tablets is wrong or untraceable in the official sources of drug information and represents a safety issue. In all cases, time consuming and costly clarifications must be undertaken, ultimately the physician must be consulted, in order to modify the prescription or to dispense the prescribed 1/2 tablets as off-label use. If splitting is allowed, the patient’s cognitive and physical capacities have to be clarified and appropriate aids have to be offered, e.g. a pill splitter, in order to insure the safe use of the drug.