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What is helium leak detection?

The pharmaceutical industry has seen a significant rise in the use of pre-filled syringes in recent years. This demand is expected to accelerate over the coming decades. Pre-filled syringes offer benefits to the pharmaceutical industry in the form of reduced drug waste and increased product life span. Health care workers consider pre-filled syringes as an efficient, convenient and reliable drug administration method. However, they pose several challenges in manufacturing and require extensive testing.

Just like any other drug product, pre-filled syringes should be free from pyrogens and should be sterile. Not just that, they are expected to be biologically, chemically and physically stable throughout its shelf life. Considering the complex nature of these products, it isn’t surprising that there are many opportunities for it to fail to meet quality requirements. Defects in pre-filled syringes mainly depend on drug product design and syringe process design. Additionally, patient related issues are also an area of concern. Therefore, it is important for manufacturers to have knowledge and understanding of various tests involved to ensure patient safety.

Container Closure Integrity testing of pre-filled syringes

Sterility is the most important quality attribute associated with any pharmaceutical/ parenteral drug product. Container Closure Integrity (CCI) testing is one of the key tests performed by manufacturers so that the product is guaranteeing sterility and microbiological quality until point of use. Container closure integrity testing evaluates the ability of container closure systems to maintain a sterile barrier against possible contaminants that can deteriorate the quality of final pharmaceutical and biological products. There are multiple methods to conduct container closure integrity tests, each with its own set of benefits and limitations. For instance, techniques like dye ingress and microbiological ingress are destructive to the samples being tested. Such tests rely on statistically representative number of samples from the batch and assume that defects are uniformly present throughout the batch. On the other hand, deterministic methods are non-destructive in nature and can be used to test every unit from the batch.

Helium Leak Testing for Pre-Filled Syringes

Helium leak testing refers to the act of finding leaks in some type of enclosed or sealed system using helium as a “tracer” gas and measuring its concentration as it escapes due to leakage. Under this technique, the package is helium filled and subjected to vacuum. The amount of helium escaping the package is quantitatively measured with the help of a helium leak detector. The result is stated as a leak rate. Apart from being an effective container closure integrity test method, helium leak testing is also applicable in product design, product quality analyses, failure analyses and validation.

Why use helium as a tracer gas?

Helium is considered as an ideal choice of tracer gas because of the following reasons:

• Helium is non-toxic, non-condensable, non-flammable.
• It is inert, making it safe for use as it will not interact with the components being tested.
• The atom size of helium is really small, allowing it to breach pathways reliably and easily.
• Compared to other tracer gases, helium is less expensive and readily available.