Nycomed tests vial stoppers to ensure integrity

A novel engineering solution has been developed to help Nycomed Amersham test its products more rapidly, as Mark Bartlett of Ametek Lloyd Instruments,* explains

Drug container integrity and safety is of paramount importance to the medical industry, and leading materials testing specialists, Ametek Lloyd Instruments has supplied advanced testing equipment and software to this industry and others for many years. Nycomed-Amersham called on its expertise recently for a cost-effective approach for testing rubber closures used to seal glass vials.

Nycomed-Amersham has to meet strict regulatory requirements for all its manufactured products, including rubber closures. For this reason, the company ensures complete traceability on all its raw materials used and is equally committed to testing components, as well as testing chemicals.

The closures Nycomed-Amersham uses are made from rubber compounds. The end product must be flexible and firm enough to allow a hypodermic needle to pierce the closure and reach into the vial without the rubber breaking apart. For every batch of closures that arrives, staff test a generous sample using standard force testing measurements to establish the physical properties and any batch to batch variation.

'Our testing policy aims to mimic the everyday use of the product,' explains Dave Ralph, QC supervisor at Nycomed-Amersham. 'We base our tests on existing BS3263 standards. Typically, we measure the forces required to push the needle through the closure, the ability of the closure to reseal, and the integrity of the rubber during frequent usage.' This final test is particularly important because small rubber fragments lodged in the needle could enter the patient on injection.

Nycomed-Amersham uses the industry proven LRX universal testing instrument from Ametek Lloyd Instruments to test the rubber closures. While such tests are vital, the manual procedures involved in this process are quite time-consuming and labour-intensive, since each closure has to be individually secured in the instrument grip before testing and analysis can begin.

'The repetitive nature of this work leant itself to a dedicated automatic testing solution,' said Lloyd Gilbert from Ametek Lloyd Instruments. 'After managers at Nycomed-Amersham explained their requirements, we turned the initial concept into a robust workable design to test closures rapidly, accurately and automatically.'

novel rack system

Engineers designed a novel rack system that attaches onto the platform of LRX and holds up to 40 glass vials with their closures. Crucially, the rack is a one piece plate design for precise positioning, and separate processor control that automatically advances the rack in an X-Y direction, similar to a microscope stage, as the test proceeds. A pneumatic needle grip, also with separate control, was developed to pick up a needle automatically from its protective cover for the test. A peristaltic water pump was also incorporated in the grip design to flush out any needle debris using water.

Nycomed-Amersham is using the latest version of Ametek Lloyd Instruments' Nexygen software for LRX control and analysis. Easy to set up, the software holds an extensive library of tests, and provides clear data analysis and advanced automation capabilities.

Full compatibility with Windows platforms and Microsoft software packages allows reports to be tailor-made according to client needs. The optional Ondio software programme enables individual tests to be written. Engineers had to ensure the X-Y table, pneumatic grip and water pump are controlled precisely in tandem with the LRX test instructions through Nexygen, so they used the same Nexygen platform to create individual software programmes to operate the new controllers. This control independence also allows staff to adjust the set-up of each individual function, for further flexibility depending on the test required.

Each rubber closure is tested with a one point penetration test, a five point test and a 25 point test. Each test is performed individually on the entire array of closures before moving onto the next test, and the results stored automatically in Nexygen files.

The one point penetration measures the forces required to push the needle in and out of the closure. Compressive forces rise as the needle is inserted, then the forces work in the opposite direction as the needle is withdrawn. Using such data, managers can set simple 'pass/fail' limits into the Nexygen software for automatic decisions on whether a batch meets the appropriate handling criteria.

rubber closure fragmentation

A five point penetration test analyses the fragmentation of the rubber closure. The peristaltic pump flushes water through the needle following each injection into the vial, and the vial is weighed at the end of the test to check for rubber fragments. Once again, pass/fail limits can be set for specific batches.

Leak tests are also conducted by piercing each closure in 25 separate places, then attempting to draw fluid dye through it under vacuum. This test determines closure resealability for safe containment of the pharmaceutical product.

The entire new automated testing procedure is benefiting Nycomed-Amersham cost-effective operations in a number of ways. Staff are now able to test 14 batches of closures in approximately four working days, as opposed to 15 days using the traditional manual method.

'The new X-Y table has accelerated our testing operations considerably,' adds Ralph. 'We are thoroughly impressed with the way Ametek Lloyd Instruments liaised so closely with us during the design stages and we recently upgraded to ensure the best possible performance to meet our exacting test criteria.'

As well as saving time and costs, this new automated capability releases more time for the technician to perform additional tasks in the department. Accuracy and precision are also guaranteed, since the speed of the injection is set every time by the computer operation. This ensures repeatable test performance, as opposed to the subjective testing techniques when performed manually.

automated testing solution

By developing this automated testing solution, Ametek Lloyd instruments is helping Nycomed-Amersham issue accurate test results quicker than ever before, which ultimately gives patients the assurances that pharmaceuticals are safely contained before they begin to roll up their sleeves. Furthermore, Ametek Lloyd Instruments can design similar X-Y tables to test other products and help customers benefit from the cost savings in quality control in a similar way.