New instrumentation for determining flexure breaking strength of capsule-shaped tablets.

New instrumentation to measure the flexure breaking strength of capsule-shaped tablets was developed. It consisted of a mechanical linkage to apply the breaking load at a uniform rate and a strain-gauge instrumented cantilever beam to convert the load to a proportional millivolt response on a recorder. A recorder tracing was obtained of increasing load with time, with a break in the tracing denoting the tablet's flexure breaking strength. Measurements were made for different tablet hardnesses, and a plot of tablet hardness versus flexure breaking strength yielded a profile of the mechanical strength of the tablet. The instrumentation was shown to have application for determining the effects of tablet thicknesses, tablet ingredients, tablet sizes, cup depths, and bisect dimensions on tablet strength.