Weight variability of pharmacist-dispensed split tablets

Abstract

Objective: To determine the level of weight uniformity of fragments from tablets split into halves and dispensed by pharmacists.

Design: Pre-post comparison.

Setting: Laboratory analysis of split tablets returned unused from four long-term care facilities.

Interventions: Twenty-two dispensed prescriptions containing 560 split tablet halves were collected, and fragment weights (FWs) were determined. Theoretical weights (TWs) of split tablets of the same medications were determined mathematically.

Main outcome measures: Comparison of the mean FW with the mean TW of each dispensed prescription and determination of whether fragments met United States Pharmacopeia 24 (USP) criteria for weight variation of whole tablets.

Results: A significant difference (P < .05) between mean TW and mean FW was found in 2 (9.1%) of the 22 dispensed prescriptions. Overall, 30 (5.4%) of 560 fragments, contained in 10 (45.5%) of the 22 dispensed prescriptions, had weights that deviated by more than 15% from the mean FW. Of the 560 fragments, 32 (5.7%), contained in 10 (45.5%) of 22 dispensed prescriptions, had weights that deviated by more than 15% from mean TW. A total of 15 (68.2%) of the 22 dispensed prescriptions had standard deviations (SDs) that were more than 6% of the mean FW. None of the TWs displayed an SD greater than the USP limit of 6%. Only 7 (31.8%) of the 22 dispensed prescriptions met USP standards, with FWs not exceeding 15% of mean FW and SDs of no greater than 6%.

Conclusion: Tablet splitting resulted in an unacceptably high incidence of weight variation. Standards should be developed to ensure uniformity of split tablets.