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The integrity of the seal between the container and the closure is a major concern when choosing packaging components for a parenteral drug product. The packaging must protect the pharmaceutical product from a number of possible sources of contamination, such as microbial ingress. Container closure integrity (CCI) is defined as the capacity of a container closure system to preserve a drug product and hence retain its efficiency and sterility throughout its shelf life. The purpose of container closure integrity testing is to determine the effectiveness of packaging closure.

To ensure CCI of pharmaceutical drugs, a number of methods are used. Helium Leak Detection is one of them. In this method, helium is used as a tracer gas, to detect leaks. This testing produces quantitative data that are more repeatable and reliable than qualitative pass/fail results. Despite the fact that it is a destructive test, helium leak testing is widely used because of its sensitivity and ability to run samples at temperatures below ambient. After the sample is prepared, it may be kept and analyzed at the proper temperature.

CCI Testing of Pharmaceuticals at Low Temperature

The CCI of pharmaceuticals may be determined using a variety of approaches. Under sub-ambient temperature circumstances, several methods of container closure integrity testing, such as blue dye ingress, microbial ingress, and vacuum decay, are insufficiently sensitive or simply unsuitable. Helium leak testing is a reliable method for testing closures and ensuring product effectiveness and sterility. This method is more sensitive than other CCI testing methods.

LDA has created the LT80, Low Temperature -80°C, Add-On test system for use with the LDA SIMS helium leak detectors to meet the market demand for analyzing leaks at cold temperatures. Concurrent temperature conditioning, temperature monitoring, and helium leak testing of packages approaching -80°C are all possible with the LT80 system. Even at temperatures as low as –80°C, helium leak detection is an effective method to ensure container closure integrity. While there are alternative methods for measuring CCI, many of them are ineffective at temperatures below –80°C. The LT150 low-temperature add-on unit allows for sample testing at temperatures as low as -150° C. The highly sensitive nature of the instrument allows for leaks as low as a 2µm hole can be recognized as a failure. The quantitative results provide the analyst with a numerical value, which allows for better data trends and greater confidence in the packaging system's performance than qualitative techniques can provide.

Container closure integrity or CCI, on packaging for parenteral drug products, is crucial for drug product preservation. The packaging closing components must be carefully chosen in order to eliminate sources of contamination that could harm the pharmaceutical product. The need to extend container closure integrity testing into the cryogenic temperature range is already becoming apparent. Container closure integrity must be achieved at cryogenic temperatures if pharmaceuticals are to be kept at cryogenic temperatures. For these types of drug items, newer packaging solutions like prefilled syringes and complex self-dosing devices are increasingly being used, and CCI will need to be proved for them as well.

Using helium as a tracer gas is the most sensitive and commonly used tracer gas leak detection technique for CCI. When moisture-sensitive pharmaceutical products are lyophilized, their shelf life is extended, and they are better prepared for storage and transportation. A lyophilized medicinal product's quality is ensured by maintaining consistent moisture content. Proper container closure system (vial, stopper, seal) selection and sealing conditions are equally important factors. Demonstrating Container Closure Integrity (CCI) is one way of achieving this goal.

Why use helium?

Helium gas is one of the smallest molecules. In addition to being non-flammable, non-destructive, non-toxic, and inert, helium only has a trace presence in the atmosphere. Helium is generally safe to employ (compared to hydrogen) since it will not react with any of the components in the test part. Mass spectrometers detect helium in the vast majority of leak testing applications. A residual gas analyzer, on the other hand, is also an option. In general, helium leak testing ensures higher levels of sensitivity than conventional pressure decay methods.

Tracer gas method to test seal integrity

Tracer gas leak testing is a simple and very effective way of detecting leaks that offer great sensitivity, accuracy, and repeatable results. Being one of the most effective method of leak detection, tracer gas leak testing offers great sensitivity and accuracy. Micro-leaks between 1x10-4 to 10-9 scc/s can be detected using the tracer gas leak test, which utilizes the tracer gas - helium. Tracer gas leak testing can be done with either pure helium or by mixing it with another gas such as nitrogen or dry air to reduce the overall cost. A mass spectrometer is used in the standard test method for measuring package and seal integrity. Due to its low concentration in the atmosphere, and its detection using a mass spectrometer, helium is employed. It is done by injecting helium into sealed packages or adding it to sealed package’s headspace after sealing. In the following step, a mass spectrometer is used to identify and measure the presence of helium in the surrounding enclosed space.

Vacuum test method is the commonly employed tracer gas method for testing the seal integrity of pharmaceuticals products. In this method, seals are put under stress by a vacuum, which measures tiny leaks. Helium transfer rate captures the real transmission rate through the material as well as via the seals. Transmission of helium through the material as well as seals is captured by helium transmission rate. As a result, the vacuum technique is more effective in detecting leaks since it monitors helium gain in the external environment within the enclosed sample.

When packaging seals are tested for integrity, it helps guarantee that the packaging offers necessary product protection for patient safety. To ensure product quality, package seals must be reliable. Seal integrity tests are commonly used to evaluate sustainable packaging options, lower-cost packaging, and changes in manufacturing line sealing parameters, among others. Evaluating the seal strength of packing materials with reduced costs and alternative sealing procedures confirms that the seals do not leak over time.

Leak Detection Associates (LDA) designs and manufactures high-performance tracer gas (helium) leak detection systems to ensure the integrity of seals for the pharmaceutical and biological industries. Helium leak detection is the one of the most effective leak detection method to identify and locate leaks in a closed system.

Helium leak detection is referred to as the process of detecting leaks in various packaged or sealed systems by utilizing helium as tracer gas and measuring its concentration as it escapes due to leakage. A package system such as a vial that consists of a container and an elastomeric closure, is a good example. The vial is filled with helium and vacuum is applied. The quantity of helium that escapes from the package is quantified and expressed as a leak rate. A pre-filled syringe, a foil pouch, or a cold form blister card are some more examples of package systems. Each of these package types is designed to keep the pharmaceutical product enclosed while keeping out potentially harmful environmental pollutants like dust, bacteria, or even gases. The helium leak testing method can evaluate each of them.

Helium leak testing is widely utilized in the pharmaceutical and medical device industries because of its relevance in guaranteeing package integrity and quality. Now, let us see how these sectors benefit by using this technique.

1. Pharmaceutical Industry: The pharmaceutical industry has experienced enormous progress in terms of technological developments and drug delivery system innovations over the last two decades. However, such developments have created new quality assurance challenges for drug manufacturers. As a result, pharmaceutical manufacturers give major priority to both quality control procedures and pharmaceutical package leak detection.

CCI Testing is a leak detection technique that evaluates the capacity of container closure systems to maintain a sterile barrier against external contamination. These tests may be divided into two types: probabilistic test and deterministic test. Although probabilistic test methods like Bubble Tests and Dye Ingress were initially common, due to technological advancements, non-destructive approaches are now the preferred way for ensuring container integrity. Hence, pharmaceutical manufacturers are encouraged to switch to more dependable deterministic test methods, such as helium leak detection, which offer quantitative findings that are assured and precise. By using helium leak detection early in the development process, companies can improve the quality of their drug delivery system. This not only saves money and time, but also improves safety.

2. Medical Devices Industry: In the medical device industry, package integrity testing is important since product failure presents considerable risks to patients and healthcare professionals, as well as liability for manufacturers. Barriers between fluids or gases are frequently used in medical equipment. These barriers must be functional in order to safeguard the patient and, in many cases, the medical equipment. Some devices operate as channels for delivering or extracting fluids to or from specific parts of the body. If a leak develops along the channel, fluids might be supplied to the incorrect place by mistake or wrong fluids could be extracted, resulting in hazardous effects. As a result, medical device industries use various CCI test methods including helium leak testing to ensure package integrity.

Helium leak testing is the most common tracer gas method in the medical device industry. Helium or a helium-air combination is used to pressurize the test component within a vacuum chamber. The chamber enclosing the part is next evacuated, generating a vacuum that allows the helium to enter the chamber through any leaks. A mass spectrometer designed to detect helium takes a sample of the vacuum chamber and ionizes any helium detected. Even a small amount of helium is easily detected in this method.

The major reason for choosing the tracer gas technique by manufacturers is the necessity for high leak-detection sensitivity in particular medical device equipment applications. Product testing is a crucial part of the device production process in the medical industry. As quality requirements have gotten increasingly strict, leak testing has become increasingly important for medical equipment as well as pharmaceutical manufacturers.

Helium leak detection technology is used to identify tiny leaks in a contained system. Other detection techniques may not be applicable due to operating limitations or if the leaks are so small that other techniques cannot find them. Due to its tiny size and inert nature, helium is an excellent choice for testing purposes. It has no effect on the materials in the item to be tested. Because of a variety of factors, helium is a preferable option as a tracer gas.

• Non-toxic, inert, and non-flammable
• The tiny atomic size makes it easy to pass through leaks

Helium is detected with a mass spectrometer or helium sniffer, however, it is also possible to utilize a residual gas analyzer. In comparison to other methods of finding leaks, helium testing is a thousand times more sensitive.

Various technologies

• SIMS 1915+

SIMS 1915+ is the ideal option for helium leak detection in pharmaceutical and medical device packaging systems. Vials, syringes, cartridges, and blister cards are some of the most common applications. Helium is commonly used to test the rubber stopper on a vial or the plunger on a syringe or cartridge assembly for leaks in parenteral goods. Sensitivity level as low as 1 x 10-10 mbar/L/sec may be measured with SIMS 1915+, which offers useful data sets instead of a basic pass/fail condition while allowing testing to be done at ambient temperature. It is important to note that each SIMS 1915+ Helium Leak Testing device is custom-built to meet client-specific requirements and package specifications.

• Cold storage package test systems

In an effort to retain product quality features, pharmaceutical and biologic firms continue to push for extended cold storage. In addition to requiring storage at temperatures below -20°C, many of these goods also require dry ice (-78.5°C) or liquid nitrogen (-200°C) for storage and delivery. However, many of the materials utilized in these package systems and responsible for preserving package integrity are not routinely evaluated at these temperatures. The glass transition state of elastomeric materials can be reached or exceeded at deep-cold or ultra-cold temperatures, causing leaks at low temperatures that would not otherwise be detected at room temperature.

• HSAM and Vial Filler

When it comes to helium-based leak testing systems, the Head Space Analyzer Module (HSAM) with vial filling assemble is a key component. As part of the HSAM, a probe measures the helium content in the headspace of a container system. With the optional vial filling assembly, previously sealed vials may be prepared for testing by replacing the headspace gas with 100 percent helium before the test is performed. After capping, this module can be used to prepare samples for testing or to prepare samples that have been kept for some time before testing. They may be used in conjunction with the VM-2 to get precise readings that can be included in flexible research designs.

• Sniffer Probe

This simple technique of tracer gas leak detection employs a sniffer probe to detect the gas's presence and locate the location of the leak. The tracer gas is initially applied to the part or system. With the sniffer probe, the operator then conducts a systematic search for probable leak spots. When it comes to finding micro leaks, sniff leak locating is quite successful. It is best used for examining smaller quantities of items. While the cost of sniffer testing depends on the kind of tracer gas utilized, it is a proven option for leak detection and localization.

• Package Test Fixtures

Outside the box, no leak testing is possible using a Helium Leak Detector. An HLD is only one component of a matrix that makes a useable system, just like a display is part of a computer system. Checking for quality packing material and sealing is a part of testing a package. By squeezing and holding it underwater, an operator checks for bubbles in a package using the manual leak testing method. The package retains atmospheric pressure when there are leaks.

• Calibrated Leak Standards

To support everyday usage, daily performance verification or system suitability tests, as well as planned certifications, LDA supplies full sets of calibrated helium leak standards. Each SIMS 1915+ has an inbuilt helium leak standard. Using a given leak rate, this technique releases a certain concentration of Helium. On each day of usage, it is utilized automatically by the instrument, or on-demand for autocalibration prior to analysis. Each external helium leak standard by LDA releases helium at a defined leak rate, similar to the internal leak standards. But instead of living inside the instrument, they attach to the test port in the same manner that a sample fixture would be installed in the system.

Some basic applications

• Glass Vials
• Pre-filled Syringes
• Bottles
• Blister Packs
• Foil Pouches
• Combination Products

Helium leak detection technology is a highly sensitive method used for detecting leaks in an enclosed system. Helium is used as a tracer gas as it is inert, non-condensable, non-flammable, and harmless. Because of its small atomic size, helium passes easily through the leaks. Thus, the change in its concentration is measured and indicated as a leakage rate. Helium is lighter than the next inert gas neon. It is also very cost-effective and can be easily delivered in various cylinders and in pure form. Hydrogen that is not inert is the only molecule smaller than helium.

Helium leak detector works on the principle of field mass spectrometer. The electric beam in the filament of the analysis tube ionizes the leaking helium gas. The ions are accelerated by increased voltage, escape through the split and later pass through the analyzer's magnetic field. The collector can only catch the helium ions and detect helium, as the circular paths of the ions rely on their mass. The ion current is transformed into an electric current using a specific detector. The current is accelerated by utilizing leak detector devices and displayed on the screen. The measured current is equivalent to the concentration of helium and hence equal to the leak.

What makes helium gas ideal for package leak testing?

• Non-toxic, inert, non-condensable, present in the atmosphere in trace amounts
• Helium gas is one of the smallest molecules to consistently and rapidly break the pathway
• Helium is non-flammable, widely available, and inexpensive
• Since it is an inert gas and does not interact with the testing component, it is, therefore, safe to use
• The noise of the instruments caused by the environmental helium is naturally minimal due to its low atmospheric level of less than 5 ppm and thus gives accurate reports

Key benefits of helium-based testing

• Helium leak detection is a highly sensitive detection technique, particularly developed to identify extremely small leaks which cannot be detected with standard leak test methods
• The leak test limit may be set at a level of 1 x 10-10 mbar L/sec, which enables unique comparisons across components, materials, formats, and manufacturing characteristics using a high-speed vacuum approach

Applications of Helium leak detection

Following are some of the common applications of helium leak detection technology:

• Glass Vials

One of the most common package systems for biotechnological and pharmaceutical products. Helium is the most appropriate and sensitive way for qualifying components for empty components and for product-filled vials.

• Pre-filled Syringes

Pre-filled syringes represent the biggest growth area of parenteral packages with the development of more sophisticated drugs for a wide range of injectable substances and increased demand for self-administration. Helium testing techniques can be developed such that these unique package systems have extremely effective test programs.

• Bottles

Bottles are one of the most used packaging methods and helium still remains the standard for quality testing purposes.

• Blister Packs

Helium is still the optimum test technique for qualifying the CFF blister cards' material components. The test procedure is based upon the detection of helium encapsulated in the packaging system as it escapes from the package via micro-channels.

• Foil Pouches

The sensitivity of the helium leak testing method provides an excellent platform to test quality control systems based on foil. This technique normalizes the helium leak rate to 100% so that all test specimens throughout the manufacturing line setup may be directly compared.

• Combination Products

Multi-chamber systems with specific needs for tests are perfectly suited for using helium leak test to guarantee that all components satisfy the rigorous leakage standards.