Tablets: the importance of uniform coating.

Introduction

As the pharmaceutical industry looks to move from the traditional batch approach to Continuous Manufacturing, it is constantly on the lookout for technological solutions enabling processes to be monitored in real time. As part of this move, IMA Group, which operates globally in the design and manufacture of packaging and processing systems, has taken the decision to develop increasingly innovative tablet processing machines at one of its Pharma divisions (IMA Active). One such example is Croma, a continuous tablet coating machine that has been upgraded with an Omron vision system to enable it to accurately assess coating uniformity, both in terms of the surface of the individual tablet and across the entire batch “The Quality by Design (QbD) concept is essentially based on principles that define the desired quality profile for both the product and production through the identification of key attributes. This means continuous process monitoring is crucial to maintaining a consistent level of quality throughout the product’s life cycle. As such, real-time and online monitoring strategies are essential to ensure the right and most appropriate levels of safety,” explains Marco Minardi, Automation Manager at IMA Active Division.

Consistent results with geometry and monitoring

Croma has been designed to facilitate truly Continuous Manufacturing, moving the product through the entire coating process. The advantages for pharmaceutical industry customers are clear: optimised production, flexible process, efficiency, reduction in equipment size and lower costs. In particular, up to 4 modules can work in series or in parallel. The tablets pass through a rotating perforated drum supplied with a flow of hot air, and their exposed surface is coated using spray guns. Market standards require each individual tablet to be uniform, both in terms of its outer coating and in relation to other tablets in the same batch.
This is why the machine’s internal geometry has been designed to guarantee maximum process repeatability. Handling all of the tablets in the same way is the first step to ensuring that the product’s appearance is uniform. However, for the result to be verified, process monitoring is also required to ensure that the quality indices of all tablets processed are analysed effectively. This is why IMA Active has opted to install Omron vision systems, which use highly customisable, high-performance industrial cameras that can be programmed in standard languages and feature the most common, up-to-date communication protocols.

Consistency equals compliance

To ensure the process is monitored continuously and accurately in compliance with established standards, the group implemented computer-based vision technology using an Omron industrial vision system equipped with a high-speed colour camera (nominal frame rate of 163 fps) and a dome light. The solution can continuously capture images while eliminating other misleading elements, such as shadows and reflections, that can impact the inspection. Within IMA Active, ad hoc tablet tracking software has been developed using Python and OpenCV. “We can monitor production easily and efficiently, processing every frame captured by the camera on the fly. First of all, the system detects each individual tablet. The position of the tablet in the next frame is then predicted based on physical considerations, which makes it easy to follow its entire journey. This means the coating of each tablet is only inspected once, thus reducing computational load. Finally, based on the data collected, significant indicators of coating uniformity for the tablets both individually and collectively are calculated and sent in real-time to the machine via OPC UA. By doing so, specific process parameters can be modified to improve the quality of the final product. This really is the definition of smart automation,” explains Giuliano Maria Emiliani, Software Engineer at IMA Active.

Visual inspection and quality control solutions are only part of Omron’s range of industrial automation technologies, which also include robotics, handling, monitoring and safety systems. In this particular case, in addition to the vision system, Omron offered IMA Active highly specialised technical support to help choose the best solution and fine-tune the system. This made it possible to assess the use of scalable solutions for the preliminary test process from the outset, which ruled out standard vision systems in favour of open technologies that offer a greater degree of freedom.

Figure 1: Omron’s vision system is equipped with a high-speed colour camera and dome light.

“When it comes to Pharma 4.0 and digitization processes, we know how important it is to take a holistic approach and ensure effective collaboration between the technology provider and the machine installer/manufacturer in order to achieve true transformation,” says Michela Siena, Key Account Manager Life Sciences at Omron.

Accurate tablet monitoring

The Croma tablet coating system equipped with Omron’s vision system has proven robust and adaptable to various product types. Any change in process performance can be easily detected by monitoring uniformity indicators. The technology is able to inspect the tablets processed by the machine by working within a Cielab colour space to identify colour variations more accurately. Overall, inspection automation has enabled IMA to achieve a new level of accuracy within the world of continuous coating. Coalescence between the product and the machine has finally been achieved: by having comprehensive knowledge of the product status, Croma can self-regulate in order to refine the process.

“This project has a clear vision of the advantages for our customers and, most importantly, for patients. Instead of using offline instruments such as colour spectrophotometers to analyse the coating of a few tablets per batch, our solution allows us to monitor production in real time. This significantly increases the reliability and overall quality of production, enabling us to provide tangible safety-related support to customers throughout the pharmaceutical world,” concludes Marco Minardi.