Tablet Compression Force as a Process Analytical Technology (PAT): 100% Inspection and Control of Tablet Weight Uniformity

The modern rotary pharmaceutical tablet press is capable of accepting or rejecting individual tablets based on the measured compression force of the tablet. Because during steady operation, each tablet is compressed to the same thickness, a larger compression force implies a heavier tablet. Tablets that are too heavy likely contain more than the desired content of drug substance. The measured compression force thus becomes an important input to the overall control strategy, and variability in the compression force from one tablet to the next corresponds directly with the uniformity of dosage units. This provides an extraordinary opportunity to use the instantaneous compression force signal as a process analytical technology to make product collection decisions on every individual tablet. Only 1 question requires investigation: how to set the main compression force limits to achieve the desired tablet weights? In this work, a small-scale characterization method and associated mathematical model are developed to answer this question.