Just because we can, we have written a brief note about the criteria that most tablet hardness testers need to follow. Why? Because when you delve deep into the world of pharmacopeia you can easily get buried beneath the terms, numbers, rules and explanations. So to cut through the fat, we will tell you the basics that apply to all tablet hardness testers on the market.
EP and USP have similar attitudes towards tablet hardness testers, and it all comes down to tolerance and force.
EP stipulates that when passing samples through tablet hardness testers, you must test 20 tablets with not more than 2 samples deviating more than the mass dependent percentage. No samples at all are allowed to deviate more than double the amount of this percentage.
USP dictates that tablet hardness testers must measure samples according to the uniformity of dosage, which involves the testing of 10 tablets that must be within the range of 85% – 115% STD ≤ 6%.
If 1 tablet is outside of this range, you are permitted to test an additional 20 tablets.
However, none of the 30 samples are allowed to be out of the range of 75% – 125% and an STD ≤ 7.8%.
These ranges are commonly referred to as tolerances, and it is these criteria that all tablet hardness testers measure against.
Some tablet hardness testers have built-in, automated functionality, like our own ERWEKA MultiCheck 6, which can test tablets according to the EP and/or USP tolerances, and record the pass or fail of a single tablet and batch by itself.
Smaller tablet hardness testers perform the test and the user simply records and/or prints the result and manually checks if it has fallen with the prescribed tolerances.
Other aspects of tablet hardness testers
There are two methods of measurement that you might come across too – constant speed and constant force.
It is important to know that tablet hardness testers capable of measuring both methods can give different values for the same tablet. And although the values are different, both results are correct.
Constant speed is the standard configuration. The moveable jaw will move with a constant 2.3 mm/s and the changing of force will be recorded.
Constant force will work with a constant force increase of 20 N/s. The speed in this case is under adaptive control.
Hopefully this has helped you shed a little light on the subject. Please contact us if we can help you in your purchasing of new lab equipment.