One of the avenues that has greatly contributed to the pharmaceutical industry’s success is packaging. Packaging has become the main method of marketing and helps manufacturers of pharmaceutical products to differentiate their products from those of their competitors.
Packaging plays an essential role in the protection of the drug against mechanical and physical damage during transportation, storage, and handling. Packaging also offers protection against biological degradation, adverse environmental conditions, and contamination that alter the drug properties. Below is a review of the packaging of pharmaceutical products using sachets and blister packs.
Two of the essential components in the makeup of blister packs are the lid and the cavity. While the cavity is made of plastic or aluminum foil, the lid can comprise cardboard, paper, plastic or aluminum, among other materials.
Predominantly used in pharmaceuticals, blister packs help in the packaging of pills, tablets, granules and capsules. A sector that especially benefits from blister packs is unit dose drugs, whereby each individual dose is enclosed in the blister. By printing the days of the week above each dose, patient compliance is further improved.
Blister packs are a packaging system that offers a considerable degree of tamper resistance – thereby preventing accidental opening by children. The blister pack’s integrity is highly significant, thus mitigating leaks between the cavities which could compromise the dose in each cavity.
However, in the case of moisture-sensitive drugs, the properties of blister packs can be compromised upon exposure to the external environment. To ensure the blister pack’s integrity, there needs to be consistency in the force needed for extracting the tablet. Therefore, it is essential to measure the force needed to penetrate a blister pack.
As seen in Figure 1, the above measurement is done using a texture analyzer – which is a highly rugged and user-friendly instrument that offers precise and repeatable results within minutes. This makes it effective for use on the production line.
Figure 1. Brookfield CT3 Texture Analyzers evaluate the strength of pharmaceutical and cosmetic materials
Moreover, the texture analyzer can determine the packaging materials’ seal strength, peel strength, burst strength and crush capabilities, owing to its numerous fixtures and probes specifically designed for testing packaging materials. Figure 2 depicts the measurement of the force needed to extract the tablet from a blister pack using a hemispherical probe.
Figure 2. Brookfield Blister Pack Support Fixture
The hemispherical probe simulates the force applied by the fingers to remove a tablet from a blister pack. It is also possible to manufacture probes complementary to the shape and size of the blister, in order to satisfy customer requirements.
During the test, the probe moves downward over a set distance, applying a compressive force on the blister pack as it lowers. As a result of the resistance exerted by the blister pack, the compressive force rises. When the blister pack can resist no more, the probe then pushes through the lid, thereby forcing the cavity’s contents out the bottom. The results of using a texture analyzer with a blister pack support fixture (TA-BPS) are depicted in Figures 3 and 4.
Figure 3. Shows results using the texture analyzer with a Blister Pack Support Fixture capsule
Figure 4. Shows the force and work required to extract a hard from a blister pack
To determine the quality of a seal barrier that protects the product from its external environment, a seal strength test using a texture analyzer is conducted. Aided by the tension testing method, seal strength measures the capability of the seal to resist separation.
A typical example of a fixture used for this type of tension testing is the dual grip assembly fixture, as seen in Figure 5. Used in tensile testing, the dual grip assembly is a multipurpose fixture. With grips that have a width of 25 mm, they are equipped with rubber inserts to increase the secure clamping of the sample, thus being able to hold rectangular samples up to 5 mm in thickness.
Figure 5. Brookfield Dual Grip Assembly Fixture
Determining the seal strength of a cosmetic sachet, Figure 6 represents a typical graph from a tension test using the dual grips with a texture analyzer.
Figure 6. Shows the load verses distance graph for the seal strength of a cosmetic sachet
As seen in Figure 6 above, the area under the graph from the start of the test to the target distance point is a measure of work that is needed to tear apart the seal completely.
The below table shows a summary of the results for one sachet.
||Peak Load (g)
||Work Done (mj)
Texture analyzers find themselves being increasingly used for this type of testing, due to several reasons:
- They allow the measurement of considerably low force levels with good accuracy and repeatability of measurement
- Texture analyzers are extremely affordable, even considering the special fixtures needed for each type of test and the training required to become proficient in using the instrument
When compared to large tension or compression testers and universal testers, texture analyzers are an easy choice – not just for research and development while doing initial characterization but also for QC pass/fail on manufactured blister packs and cosmetic sachets.
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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