Drug Content and Weight Uniformity for Six Commonly Split Medications

Abstract

Objectives: To determine the active drug content and weight uniformity for half tablets of commonly split medications as a means to outline the safety and efficacy of tablet splitting. Methods: This analytical study was performed using the following six medications: warfarin, simvastatin, metoprolol succinate, metoprolol tartrate, citalopram, and lisinopril. Whole tablets (n=15) and half tablets (n= 30) were analyzed for drug content using high pressure liquid chromatography as compared to established standard curves. Weight uniformity was assessed using half tablet weights as compared to one half of the average whole tablet weight. Results: Percent deviation from the expected drug content for all drugs analyzed ranged from 81%- 126%. All drugs produced tablet halves falling outside of the range of 90%-110% for active drug content: warfarin (1), simvastatin (3), metoprolol succinate (10), metoprolol tartrate (4), citalopram (5), and lisinopril (10). Percent relative standard deviation for drug content was less than 6% for all drugs analyzed. Weight uniformity, defined as 85%-115% of the expected weight, was found for all drugs analyzed with the exception of lisinopril, with one half tablet at 122% of the expected weight. Statistical significance for the data was not determined. Conclusions: Half tablet drug content uniformity was not concluded for the medications/ manufacturers studied. To determine true safety and efficacy of tablet splitting, additional research must be performed assessing clinical endpoints using patient-split tablets. Furthermore, USP methods for assessing drug content uniformity must be developed for half tablets, as a means to determine which medications are safe to split.