One critical aspect of ensuring product quality is the Visual Inspection of parenteral products. Visual inspection aims to reject and identify defects, contaminants and irregularities that might compromise product quality. To challenge and safeguard their own visual inspection processes, pharmaceutical companies employ Visual Inspection test sets, which are indispensable tools for personnel training and qualification, as well as in the tuning and qualification of Automated Visual Inspection systems.

What is Visual Inspection in pharma?  

Visual Inspection is a GMP process step that involves carefully examining parenteral finished products, containers and packaging materials to identify defects, impurities and any deviations from the intended quality standards. This inspection process is crucial for ensuring that products meet the stringent requirements set by regulatory bodies and industry standards. Visual Inspection contributes to the safety of pharmaceutical products before they reach the patients. 

The role of Visual Inspection test sets 

Visual Inspection test sets are positive controls: the containers in these sets contain each one known visual defect that is to be detected by a human operator or by an automated inspection machine. These positive controls are designed to facilitate the evaluation, validation and training of visual inspection systems and operators. Test sets typically contain between 10% and 25% of known defects, while the rest of the containers in such a set are confirmed good units that don’t show any of the defects considered by the client. 

Some key points about Visual Inspection test sets: 

  • Purpose: Visual Inspection test sets are used to evaluate the effectiveness of Visual Inspection systems and human operators in detecting defects, contaminants and irregularities in products during their qualification. Before that, the sets can also be used in operator training or during vision tuning of an automated inspection system. An increasing trend involves the creation of highly specialized test sets exclusively comprising particulate matter defects. These sets are designed for Threshold of Size studies, with the objective of determining the minimum particle size at which a 70% rejection efficiency is achieved for various particle materials. 

  • Standardization: the samples in Visual Inspection test sets are manufactured to mimic different types of defects, including particulate matter, glass particles, container defects, and cosmetic imperfections. For standardization purposes, not only microscopic measurements are applied but also other product characteristics can be taken into account such as colour, turbidity, surface tension of viscosity. 

  • Validation and qualification: Visual Inspection test sets are used during the validation and qualification processes of Visual Inspection equipment and operators. They help ensure that inspection systems are functioning correctly and that operators can reliably identify potential defects. 

  • Training: Visual Inspection test sets are also valuable for training new operators. They provide guidance for trainees to identify defects before moving on to qualification. This helps improve operator accuracy and consistency. 

  • Quality Control: also personnel performing the test for visible particulate matter at Quality Control is best trained and qualified using Visual Inspection test sets. This contributes to maintaining product quality and regulatory compliance. 

  • Regulatory Compliance: regulatory bodies, such as the United States FDA and the European EMA, recommend the use of Visual Inspection test sets as a way to ensure compliance with industry standards for particulate matter testing. The use of these standardized sets has become a regulatory expectation.

  • Types of Defects: Visual Inspection test sets can include a wide range of particles, such as glass fragments, fibers, hairs, scratches or rubber fragments. Also different product defects are mimicked: discolorations, increased turbidity, mix-up and under- or overfill. Among container defects we typically see scratches, cracks, glass inclusions, deformations and various stopper or plunger defects. 

  • Innovations: at eyetec we have specialized in the development of Visual Inspection test sets for freeze-dried (lyophilized) products. We have also obtained good results in the development of placebo’s when the product is not available. Last but not least we are also developing test sets for training and qualification of operators that will ‘read’ media fills. This important step in Aseptic Process Validation (APV) is aimed to detect containers that are microbially contaminated often seen as increased turbidity and/or discoloration of the media.  

  • Treshold-of-Size (ToS) studies: Visual Inspection test sets enable companies to assess the performance of inspection systems or human operators in detecting defects of different sizes and characteristics. This information can be used to optimize the inspection process if needed. It is also becoming a regulatory expectation to have such data available. 

  • Upon client request we can add a preservative to the product in order to prevent microbial growth in case contamination would occur during production of the manufacture of the positive control. Because we have a good track record of aseptic preparation and because we often see that these preservatives influence the appearance of the product, we often advise against this. Other sterilization methods such as filtration and heat sterilization are also at our disposal.

  • Stability and shelf-life: It is most important that each test set is approved by the client’s QA before its first use. Also the test set should be reviewed periodically by experienced operators to confirm that the defects are still visible, that the good units don’t show any defects and that there is no sign of deterioration of the test set. These reviews have to be documented in order to validate the training or qualification the set is used in. The Visual Inspection test sets can be used as long as they pass these reviews. While some sets won’t even last three years due to their intensive use, other sets have been known to last up to eight years.  

Overall, Visual Inspection test sets are critical tools for maintaining the quality and safety of pharmaceutical products. They contribute to the overall performance of Visual Inspection processes by ensuring that defects and contaminants are reliably identified, ultimately safeguarding patient health and product reputation.