Evaluation of the Strength of a Scored Oblong Tablet

Abstract

In order to evaluate the resistance of an oblong tablet with a center groove to breaking into halves, various tests for measuring the tablet breaking load were performed. The results were compared with those of a shock test which was considered to simulate the impacts occurring in the processes of packaging, handling and transport. It was found that the hardness values obtained from the Monsanto hardness tester were independent of the shock test data. This may be due to the difference in mechanism of tablet fracture between the two tests. In the bending test, all the test tablets cleanly fractured into halves. However, the values of breaking load obtained from a Kiya hardness tester were, on the whole, too small to be useful for distinguishing between tablets having different strengths. Since this result seemed to be caused by the high loading rate in this test, the influence of the loading rate was examined by the use of a material testing machine. When the rate of loading was sufficiently slow, higher breaking load values were obtained and differences in mechanical strength between the different tablets were easily detected. The flexure breaking loads obtained from the tester with a spring balance were in good agreement with the corresponding shock test data. In this test, the actual loading rate may be reduced by the buffer action of the spring, resulting in both higher breaking load values and greater apparent differences in strength between the test tablets. It is thought that this instrument is suitable as a conventional device for evaluating the fracture resistance of this type of tablet.