Barzanti: The concept of QbD is strictly related to critical quality attributes (CQAs) of the product and to the critical process parameters (CPPs) that are controlled in order to ensure that the product attributes are within the desired limits. Most tablet presses are now fitted with indirect weight control through compression force, allowing 100% in-line control of the most important CQAs of a tablet, such as the weight, as well as self-adjustment of machine working parameters to keep the process within the proper design space. Tablet hardness and thickness can be statistically controlled with an IPC auxiliary unit. In the future, an increasing number of process parameters will be controlled on-line, with the aim of ensuring the quality of other critical tablet attributes and possibly to achieve a real-time release.
Concerning continuous manufacturing, this is not an issue for the tabletting process as this is already running continuously. Probably one of the most important changes will be an increasing integration with upstream and downstream processes (granulation and coating) as soon as they have been developed to operate in a continuous mode.
Again, a very important presupposition for such an integration is a good control of the process and a quick feedback on the machine parameters, therefore avoiding any disturbance in the upstream parameters to propagate downstream.
Kettler: QbD will be adopted, in one form or another, by all drug providers who recognise the need to present their drug development process in a format that is expected by the regulatory agencies. Continuous manufacturing offers opportunities for companies to better leverage return on their capital assets as well as produce drug products on a reduced timeline.
QbD will play an integral part in continuous manufacturing. The formulation generated by a continuous process must perform on the tablet press without problems so that the tablet manufacturing process is indeed continuous. Powder flow and compression must be designed to meet the needs of all of the unit operations, not just the tablet press.