The importance of weight in pharmaceutical packaging

Mike Munnelly, marketing manager product inspection Life Sciences Manufacturing, Thermo Fisher Scientific explains why weighing is an essential part of quality control for pharmaceutical packages.

Pharmaceutical manufacturers are governed by strict standards for quality assurance and quality control (QA/QC) across the entire production process. The required rigour extends into the packaging of those pharmaceuticals as well, including how manufacturers verify package contents by weight.

The Role of the Checkweigher

Pharmaceutical checkweighers are used to weigh individual pharmaceutical packages inline, ensuring each package falls within a specified weight range. If a package is too light, perhaps missing a single blister pack, it will fail the checkweigher test. Likewise, boxes with too many blister packs would also be rejected.

Letting a product leave the facility with too many or too few blister packs or missing other components is not trivial. Most important is patient safety. If a box contains an incorrect amount of product, it could affect a patient’s outcome. An error in packaging also tarnishes a brand’s reputation and leads to potentially costly and disruptive recalls. A mishap resulting in a recalled pharmaceutical product can, depending on the product type and number of batches affected, have a significant financial impact on the manufacturer. Equally damaging are customer complaints over poor quality products, especially when they go viral on social media, as loss of brand reputation can have a dramatic impact on sales.

Inline checkweighers are now common across many manufacturing applications, but not all checkweighers are built for the rigours of pharmaceutical production. Pharmaceutical manufacturers must consider production factors such as line speed, package size and type, package transfer and vibrations from plant equipment when implementing a checkweigher solution. They must also comply with extensive regulatory and quality standards that can add cost and complexity to production if not properly implemented.

Production Challenges

Pharmaceutical packages in the form of cartons, blister packs, glass vials, plastic bottles, aerosols and pouches are typically lightweight, creating a special challenge for checkweighing. The variance in weight between a correctly packaged product and an over -or - underfilled one can be 100 milligrams or less. Consider an informational leaflet legally required to be included in the package: it weighs so little that a checkweigher not set up properly or not sensitive enough could pass a package without it. This could lead to customer complaints or require a product recall. The margin for error for checkweighers in pharmaceutical production is small.

Another challenge, common in many production environments, is the effect of vibrations from other plant machinery on checkweigher accuracy. Even seemingly minor vibrations can affect a reading and lead to a false-rejection or passing of an out-of-spec package. A checkweigher fit for this specific purpose must incorporate a design that shields against vibration and other seemingly minor environmental influences such as airflow.

Line speed can also impact the performance of a checkweigher. Packages on a fast-moving production line are harder to weigh accurately. As they are transferred from belt to belt at high speed the settling time during weighing is increased. The light weight of typical pharmaceutical products means that they are also at risk of rotating or falling during transfer which can impact downstream operations.

Checkweighers designed specifically for pharmaceutical applications are built to overcome the challenges outlined above. These more advanced checkweighers can accurately weigh light packages at speeds as high as 650 packages per minute. They are also often equipped with features to maximise weighing accuracy. For example, a closed cabinet design shields packages from environmental factors at the point of weighing and a slack belt conveyor design reduces vibrations introduced by the operation of the checkweigher itself. Finally, a knife edge design minimises dead zones on product transfer, reducing the chance that packages will be knocked around and disoriented.

Regulatory Challenges

Process control equipment can help alleviate the many production challenges that manufacturers need to solve for, but strict regulatory requirements and quality control standards increase the complexity and cost of pharmaceutical production. For example, manufacturers must comply with the US Food and Drug Administration’s (FDA) Title 21 CFR Part 11 which mandates that the software used on systems like checkweighers produces auditable electronic records with high levels of data integrity. There are also prescriptive standards such as Good Manufacturing Practice (GMP) that manufacturers must adhere to in order to remain competitive in the market.

A pharmaceutical checkweigher may come with the requisite features to make it compliant, but it isn’t a plug-and-play solution. It’s critical to partner with a knowledgeable and trusted equipment provider who can work closely with the manufacturer to implement an effective checkweighing solution that adheres to all regulatory guidelines. 

Installation qualification (IQ) is conducted with the support of the equipment provider to ensure the system is set up properly and optimised to suit the production environment, determining the specifications the checkweigher needs to meet for it to function as an effective QA/QC tool. The qualification team documents this set up, which serves as an important tool for the operator should the system be audited in the future.

Manufacturers should also rely on the provider to support operational and performance qualification (OQ and PQ), the detailed set of instructions for the operators in the operation and ongoing verification of the checkweigher system performance. The qualification team can consult with the manufacturer and help them develop standard operating procedures (SOPs) to standardise operation of the checkweigher, reducing the risk of any errors.

Making the Right Choice

To mitigate the risk of product recalls due to improperly packaged pharmaceuticals, manufacturers should implement a checkweighing solution that is built specifically for the application. The right checkweigher is equipped with the features necessary to ease regulatory compliance, overcome production challenges and ensure it meets the high standards set by industry leaders. But even the perfect checkweigher takes work to implement, which is why selecting a trusted and knowledgeable equipment provider can ease much of the burden that is involved with installing a checkweigher. This is why it is critical to partner with a provider who can help every step of the way, offering guidance on everything from the placement of the checkweigher online to what instructions should be included in an SOP.