Faster, more sensitive leak testing for vials

Related tags Ampoule Methylene blue

Spain's Telstar Industrial is developing a technology for leak
testing of pharmaceutical packages that could revolutionise the way
this vital quality control function is carried out in the industry.

The company is developing a prototype leak tester for vials using the technology, based on a process known as helium accumulation, that could be up and running by the end of the year, according to Miquel Galan, Telstar's director of innovation and R&D.

He told​ that the technology can offer a hike in sensitivity to current methods, including the methylene blue dye test (MDT) and technologies based on pressure decay, while also providing a massive increase in throughput. And this should be achievable in a machine that is not much more expensive than current models, he added.

Helium accumulation involves using the gas as a tracer to see if there is transfer from one side of a container (e.g. inside a vial or blister pack) to another.

The method is from 10 to 100 times more sensitive than current methods. The MDT test - which involves dunking blister packs in the dye, raising the pressure and then seeing if the dye penetrates into the blisters - is still widely used but is destructive, requires an operator who must make a subjective judgement and can only really pick up leaks of 20-30 microns in diameter.

Meanwhile, pressure or vacuum decay is more sensitive - picking up holes as small as 5 microns - but is slow, sensitive to temperature variations, does not allow leaks to be pinpointed and can be prone to false-positives, said Galan.

Telstar believes that using the helium technology its new machine should be able to detect holes as small as 1.3 microns, at a rate of 200 vials per minute, and will be fully validated, making it easy to comply with regulatory audit trail requirements.

The company is designing the machine to be modular so that several detectors (mass spectrometers) can be used in parallel, hiking throughput up to the levels required for testing each vial as it comes off the production line.

And while the company is focusing on a vial product to begin with, the technology could equally be applied to blister packs, foil pouches, thermoformed packages, ampoules etc.

This level of sensitivity is significant because it provides very robust evidence that a vial's integrity - and therefore sterility - is maintained, said Galan. This provides a greater degree of comfort for manufacturers and regulators, even though there are as yet no legal limits set for sensitivity in leak testing. However, Galan believes that sensitivity thresholds will be forthcoming, as the US Pharmacopoeia has already started doing some work in this area.

But will the pharmaceutical industry decide it needs this level of sensitivity and embrace helium accumulation as a test? "Why not?" says Galan; in fact, he believes this is almost inevitable.

He noted that the technology first appeared in the 1950s, and even in the 1980s its use was confined to nuclear plants. But since then its adoption across other industries has been inexorable, starting with refrigeration and automotive companies but now permeating throughout a plethora of industrial sectors.

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