Push-Through Test for Pharmaceutical Blister Packs

Pharmaceutical tablets and capsules are commonly packaged in blister packs that protect the enclosed tablets and capsules from moisture and contamination. This optimizes the product stability and maximizing its shelf-life. The two primary components of a blister pack are the rows of cavities, typically made of thermoplastic, and the lidding seals that can be made of paperboard, aluminum, or plastics. However, in pharmaceutical packages, aluminum foil is most frequently used. It is important for manufacturers to ensure that the blister pack does not break too easily but yet it needs to be brittle enough to allow consumers to break by hand in order to dispense the tablets or capsules.

We were asked to provide a solution to measure the force required to push a table through its blister pack. Our Engineered Solutions team designed a simple custom fixture to meet this application requirement. The top-down clamps are adjustable to suit different dimensions of blister packs and the lower base holder includes spacer plates with various cut out sizes to cater to different dimension tablets and capsules.

We performed the test using a 5965 table model frame and the 3^®Bluehill Biomedical Materials and Medical Devices Application Module. We first fixed the blister pack onto the lower base holder with top-down clamps and then applied a force with a flat tipped probe (with a 10 mm diameter) at 20 mm/min to push the tablet out from the blister pack.

We recorded the maximum force required to press the tablet out from the blister pack in Bluehill 3 Software. From this, we can determine if the lidding material is too brittle or if the adhesive strength between the lidding backing and the plastic-formed cavity is strong enough.