Dec 2021

Blister Pack Leak Testing: The Limitations of the Blue Dye Test


Blister packages are a convenient format for users and a practical way to keep tablet and capsule quality preserved. The majority of blister package applications are considered low-risk, and they do an excellent job of protecting pharmaceutical products from moisture intrusion, which can cause product degradation. Tablets with a hydrophilic nature, or a natural tendency for absorbing moisture, require extra protection.

Due to an increase in the number of hormone-based and steroidal therapies in recent years, worries concerning the integrity of blister packing have emerged. Given their propensity to degrade and impair treatment outcomes, packaging these and other groups of pharmaceutical products is considered a high-risk application. To combat this, most manufacturers choose a totally aluminum, cold-formed package, which offers the best protection against oxygen penetration, while some industries have packaged very sensitive steroidal therapies in thermoformed blister packaging. As these products are more susceptible to environmental conditions than most other tablets and capsules, it is critical to inspect for tiny leaks, regardless of the packaging utilized in this high-risk application.

Limitations of Blue Dye Test

One or more blister packs are submerged in a chamber holding blue liquid and a vacuum is drawn to conduct the blue dye test. The chamber is then restored to atmospheric pressure, and the packages are retrieved and examined to determine if any dye has entered them. No defect is detected if there is no dye in the blister packaging. The blue dye only enters the package after the vacuum phase, which is the major defect of this method. As a result, when the chamber is returned to atmospheric pressure, nothing prevents the operators from removing the packages from the dye during this final stage.

Package headspace and dye surfactant concentration are the other difficult factors to control in the blue dye test. In reality, the test just determines how easily or quickly the dye may enter the blister cavity. It does not tell you about oxygen or vapor intrusion. This is a significant disadvantage since gaseous pollutants may penetrate foil and film more readily through a tiny leak, which is subject to surface tension. This requires a relatively large single passage to enter the package. Another major disadvantage and difficulty to control is the subjective nature of the operator's inspection.

Leak Testing Blister Packages Using Deterministic Test Method

Helium leak testing is a deterministic method for identifying package leaks in blister packs using helium as a tracer gas. The change in its concentration is measured as it escapes due to leakage. The quantity of helium that escapes from the package is expressed as a leak rate. Helium leak detection is a very sensitive technique for testing pharmaceutical package integrity.

Seal Integrity Monitoring System (SIMS) 1915+ is the optimum leak detection system using helium. When compared to traditional methods such as vacuum bubble and dye penetration test, packages may be quantitatively examined with high accuracy. This method enables a comparison of different packaging materials and forms, as well as production line settings and storage conditions, thus supporting the entire life cycle. Package design, tooling qualification, production line setup and ongoing product quality monitoring are the applications that come under SIMS 1915+. It is specially designed for the pharmaceutical and medical device industries.

blister packs, helium leak testing, helium leak detection, helium mass spectrometry, mass spectrometry
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