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Testing the integrity of blister packages is essential to guarantee that the packaging safeguards the contents from oxygen, moisture or contaminants. Packaging keeps the product safe and functional by preventing air ingress.

Probabilistic test methodologies have been widely used to conduct blister package integrity tests, such as the blue dye test method. These tests rely on a range of sequential or simultaneous events, each with random results that are characterized by probability distributions. In order to acquire relevant results, it is necessary to use large sample sizes and strict test condition controls because the findings are related to uncertainty. Studies have also revealed the unreliability of such testing, which frequently fails to detect leaks that could endanger the quality of a product.

As a result, it is preferable that the integrity test method be deterministic. The leakage event being detected or measured in this type of test method is based on phenomena that follow a predictable chain of events. Helium leak detection is an example of a deterministic, highly sensitive method.

What is Helium Leak Detection Technology?

Helium Leak Detection Technology is a Container Closure Integrity test (CCIT) method found to be highly effective in evaluating the integrity of a wide range of complex pharmaceutical and parenteral products. Helium leak detection can be understood as the process of identifying leaks in any closed or sealed system with the help of helium gas and measuring its concentration as it escapes due to leakage. Common applications of helium leak testing include pre-filled syringes, cold form blister packs, foil pouches and many other package formats. The technique uses helium as a tracer gas and its concentration is measured as it escapes through the leaks. Under this method, the package is helium filled and subjected to vacuum. The amount of helium escaping the package is quantitatively measured and stated as a leak rate.

Why is Helium used as a Tracer Gas?

Helium is used as a tracer gas because of certain unique qualities that make it ideal for leak testing.

• Non-toxic, non-condensable, non-flammable.
• Helium gas is inert, which means it does not interact with the components being tested.
• Since the atomic size of helium is small, it can easily breach through pathways reliably and easily.
• Compared to other tracer gases, helium is less expensive and readily available.
• Its presence in the atmosphere is not more than 5ppm.

Technology Overview

The procedure begins with filling the package with helium, after which vacuum is applied within a chamber. The amount of helium escaping from the package is then quantified using a helium leak detector. This is then referred to as the leak rate. Helium leak detection technology is also suitable for package design, failure analysis, tooling qualification, packaging line setup and validation, and product quality monitoring, in addition to leak testing. ASTM F2391 helium leak detection is a well-established method recognized and widely used in the pharmaceutical industry.

Applications of Helium Leak Testing

• Ensuring Container Closure Integrity.
• Selecting closure formulation and configuration.
• Seal integrity monitoring during stability studies.
• Extremely valuable in early-stage pharmaceutical product package system development.

Blister packs are pre-formed packaging that are commonly used for tablets, capsules and certain consumer goods. They are made up of two primary components - a cavity made from a form of plastic or aluminum and a covering made from aluminum, paper or a lamination of soft foil. The cavity holds the product while the covering seals the product in the package.

While filling tablets into blister packs, the product is first fed into the desired cavities followed by sealing the cavity covering. Manufacturers of sterile pharmaceuticals highly depend on package integrity testing to verify product quality and safety.

Package Inspection Techniques

1. OptiPac Leak Detection System

OptiPac Leak Detection System is a non-destructive container closure integrity testing method developed specifically for multi-cavity blister packs. This leak detection method uses One-Touch Technology to achieve a rapid test cycle without requiring any changeover or sample preparation. Practical operation, sensitivity and reliability are the key features that make OptiPac technology ideal for blister package inspection.

To conduct the test, the operator places the blister pack on the test plate and presses the start button. The next step involves pulling vacuum to the desired vacuum level. The blisters expand under vacuum, driving air out of the blister through any leaks present. If the pack is defective, the air escapes into the chamber leaving a collapsed blister cavity. Depending on the blister cavity, OptiPac technology provides rapid detection of upto sub-5-micron defects. Additionaally, the technology displays a definitive pass/fail result along with quantitative measurement for each package tested.

2. VeriPac 410 Series

The VeriPac 410 inspection system utilizes a combination of Vacuum Decay technology and differential force measurement for container closure integrity test (CCIT) and leak detection of blister packs, sachets, and pouches with low headspace, such as transdermal patch packaging and suture packs. This technology can be used to test multiple packages in a single test cycle based on the package specifications. Additionally, it can also precisely identify which package or blister cavity is defective. VeriPac 410 inspection systems are proven to provide quantitative test results with a definitive pass/fail result. Being a non-destructive technique, VeriPac 410 allows tested products to be returned to the production line. This eliminates the cost and waste associated with destructive leak test methods. The ROI for the VeriPac 410 makes this a powerful solution for the pharmaceutical industry.

Benefits of VeriPac 410 Series

• Non-destructive, non-invasive, no sample preparation
• Non-subjective, accurate and repeatable results
• Capability to test multiple packages in a single test cycle
• Identifies which package is defective
• Simplifies the inspection and validation process
• Supports sustainable packaging initiatives
• ASTM test method and FDA standard
• Cost effective with rapid return on investment
• Scalable to automated inline testing.