Blister packs, which are often referred to as Press-Through Packages (PTP), offer a number of different benefits. Thus, it is not surprising that blister packs are being rapidly adopted by the pharmaceutical industry for medication packaging.
According to the Pharmaceutical Packaging Industry 2011 yearbook, blister packs accounted for 17% of the global pharmaceutical packaging industry, contributing approximately $8.1 billion in revenue.
Blister packs are regularly used in nursing homes and similar care settings, i.e. in situations where it is mandatory for patients to strictly adhere to dosage compliance. Studies have proved that a calendar blister pack is more convenient for this group of users to keep track of their medication scheduling.
Even though calendar type blister packs resolve some issues, there are still many issues surrounding their use by the aged or those in need of care. Users who are frail, old and have multiple ailments, especially those who struggle with finger-related mobility and dexterity may find it hard to open blister packs to access vital medication. Worse, there can be nothing more frustrating than crushing or destroying the pill in an effort to get it out of the blister pack.
Testing the Physical Properties of Blister Packs
This challenge also gets compounded when different-shaped and different-sized tablets are packed in a range of styles of blister packs, thus requiring differing techniques and forces to extract the medication. Pharmaceutical and packaging manufacturers have thus measured the force required to remove the medication from the blister pack, in order to make sure that it falls within the patient’s strength capability.
Interestingly, when it comes to test methods to measure the physical properties of blister packs, the most important objective remains to quantify the maximum force required to expel the medication through the foil.
Figure 1 shows a texture analyzer – an instrument that functions at a constant speed with high precision – that can easily conduct this simple test. The texture analyzer will measure, with great precision, the force required to push the medication through the blister package.
Figure 1. Brookfield CT3 Texture Analyzer
First, the test sample is arranged on the Blister Pack Support Fixture. Then, a test probe in the shape of a human finger moves downward towards the test sample, contacting and expelling the tablet out the foil side on the bottom. As shown in figure 2, both the blister pack support fixture and the finger probe can be custom designed, depending on the size and shape of the medication and blister packaging.
Figure 2. Blister Pack Support Fixture
Meanwhile, the Blister Pack Support Fixture (part number is TA-BPS) is used for measuring the amount of force to push a tablet or a capsule out of its container. This involves aligning the test sample over the hole in the support fixture and directly under the finger probe.
Thus, this helps the instrument to accurately reduce external effects, and accurately determine the force related to extracting the tablet. While the test is underway, the real time data shows the force build-up to a maximum value. At this stage, the resistance of the blister is ultimately broken and the tablet moves through the foil backing.
The primary information obtained from this test is the peak force recorded during the probe’s descent onto the packaging. This value indicates the difficulty level of removing the medication from the blister pack. The graph in Figure 3 shows a Vi inch Finger Probe traveling at a speed of 1 mm/sec. This generated the maximum force needed to expel a 4 mm and 8 mm diameter hard round tablet from their respective blister packs.
Figure 3. Maximum force required to extract 4 mm and 8 mm diameter round tablets from blister packs
Interestingly, the results showed that a higher peak force was needed to pop out the smaller 4 mm diameter tablet from the blister pack, while the 8 mm diameter tablet only required 5,100 gm of force. Thus, the test results prove that it was almost 43% harder to expel a smaller tablet than a larger tablet from these blister pack samples.
A further design review is needed to judge whether the recorded forces of 7,300 gm and 5,100 gm on respective samples will be easy or difficult for senior citizen patients or those who have manual dexterity/strength limitations. The above described testing is easy, quick and can be easily repeated to clearly measure the maximum force needed for opening the blister pack samples.
Such data is needed for effective product development and meaningful quality control, ultimately removing the guesswork from packaging design. Further, it equips production with the necessary tool for performing a useful quality control test, and identifies product non-conformance that could potentially reduce customer loyalty.
At the end of the day, customer satisfaction does not depend on just tablet/capsule color and attractive packaging, but also on the protection afforded to the medicine and its ease of extraction for the consumer.
About AMETEK Brookfield
Brookfield, a business unit of AMETEK Inc, is the world leader in viscosity measurement and control of liquids and semi-solids for 80+ years!
We manufacture and distribute globally viscometers the AST 100 for advance sensor technology for simple, direct in-line viscosity measurement, DV2T Touch Screen with temperature measurement, rheometers DV3T for measuring yield stress and viscosity, RST Controlled Stress for challenging rheological measurements, CT3 Texture Analyzers which features compression and tension mode for measuring firmness, springiness and chewiness and PFT Powder Flow Testers which measure yield stress and viscosity flow index and arching dimension used in R&D, QC and inline applications for rheological fluid analysis, tension and compression and powder flow analysis.
Markets include: food cosmetics, pharmaceuticals, oil & gas, personal care products, adhesives, printing, inks & coatings, paper coatings, chemicals, packaging, plastics, construction materials, and asphalt.
Brookfield AMETEK manufacturers and services a full range of viscometers and rheometers, texture analyzers, and powder flow testers. Additional services include: testing for viscosity, texture and powder properties, calibration and certification program, custom fixture development, free technical papers, seminars, videos, application notes, manuals, and educational and training programs.
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