Review of real-time release testing of pharmaceutical tablets: State-of-the art, challenges and future perspective.

In the last decade significant advances have been made in process analytical technologies and digital manufacturing of pharmaceutical oral solid dosage forms leading to enhanced product knowledge and process understanding. These developments provide an excellent platform for realising real-time release testing (RTRT) to eliminate all, or certain, off-line end product tests assuring that the drug product is of intended quality. This review article presents the state of the art, an RTRT development workflow as well as challenges and opportunities of RTRT in batch and continuous manufacturing of pharmaceutical tablets. Critical quality attributes, regulatory aspects and the scientific basis of enabling technologies and models for RTRT are discussed and a systematic development workflow for the robust design of an RTRT environment is presented. This includes the discussion of key considerations for the identification of the critical quality attributes and points of testing as well as the development of the sampling strategy, a hard and/or soft sensor approach and operational procedures. The final sections present two RTRT use cases in an industrial setting as well as critically discuss challenges and provide a future perspective of RTRT.

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.

Characterizing drug product continuous manufacturing residence time distributions of major/minor excipient step changes using near infrared spectroscopy and process parameters.

The material residence time distribution in a continuous manufacturing process can be utilized to develop, design and justify the process control strategy. This paper successfully demonstrates using both major and minor formulation component step changes to determine the system response using either Near Infrared Spectroscopy or process parameters. These options provide development flexibility to determine the system's material residence time earlier in the development process and more cost effectively.

On-line monitoring of blend uniformity in continuous drug product manufacturing process--The impact of powder flow rate and the choice of spectrometer: Dispersive vs. FT.

One of the commonly acknowledged issues in continuous manufacturing of drug products is how to provide a representative sampling on flowing powder to assure its blend uniformity. An investigation was conducted to improve understanding on the impact of powder flow rate under different continuous manufacturing conditions and the impact of optical parameters (such as resolution, co-adds, and integration time) on NIR spectral quality with respect to a dispersive and a Fourier transform instrument. A partial least squares (PLS)-based spectral pretreatment was found useful to tackle the impact of different flow rates on NIR spectral signals. Multivariate figures of merit (FOM) were used to evaluate performances across different instruments and optical settings and discover the advantageous selectivity and sensitivity on the Fourier transform than the dispersive instrument regardless of the use of co-adds.