Pharmaceutical containers can be tested for Container Closure Integrity (CCI) in a variety of ways. Blue dye test and bacterial or microbial immersion test come under traditional, probabilistic methods. Whereas Vacuum Decay, Airborne Ultrasound, MicroCurrent HVLD, and Helium Leak Detection belong to the deterministic group of test methods. Each approach has advantages and disadvantages that should be considered while selecting a test method for a certain container type. All the methods are not appropriate for all sample configurations. Some succeed in certain applications while failing in others. Nowadays, the pharmaceutical industry is moving away from the traditional blue dye and bacterial immersion test methods and approaching deterministic methods for CCI testing.
The helium leak rate method is proven to be a strong contender for many applications. Helium leak testing is described as the process of detecting leaks in various enclosed or sealed systems by utilizing helium as a "tracer" gas and measuring its concentration as it leaves due to leakage. Like most CCI methods, Helium Leak Detection is deterministic. This method is more sensitive and not prone to contamination as compared to traditional dye or bacterial immersion methods. Due to its highly sensitive nature, it is possible to detect extremely small leaks, which are not possible with other leak testing methods.
Validating Helium Leak Rate Method for Pharmaceutical Containers
Validation of a Helium leak rate method for pharmaceutical container closure integrity assurance required proof that this physical testing method was as excellent as, if not better than, microbial immersion challenge testing in detecting potential integrity problems. Helium leak rate and microbial challenge tests were performed on one lot of rubber-stopper, broth-filled glass vials, which include faulty vials with known leaks. Glass micropipettes (0.1 to 10 microns) were fitted into the sidewalls of the vials to prepare defective vials. A 10% seeded defect rate was present in the validation lot, with nearly 50% of the leaks having a predicted probability of failing a microbial challenge (> 10%). The test units were charged for 4 hours under 40 psi helium pressure to implant the helium tracer in them. After charging, the crucial leak rate was found to be 10(-7) standard cc/second, and test units with measured leak rates exceeding this value were considered helium leak rate failures.
Microbial immersion challenge was performed by immersing the test units for 24 hours in a bath containing 10(9-10) viable E. coli and B. diminuta organisms, followed by a 13-day incubation period at 35°C. Visually, microbial failures were identified. The mean failure rates of the helium and microbial leak test techniques were compared statistically. The average helium failure rate was 6.9%, whereas the average microbial failure rate was 2.8%. There was a considerable difference between helium and microbial failure rates. As a result, helium leak rate testing has been shown to be an acceptable pharmaceutical container/closure integrity method for container quality assurance.
The helium leak detection method is chosen to be one of the best techniques for ensuring the integrity of pharmaceutical containers. This technique may be used to test the inherent package integrity and the Maximum Allowable Leakage Limit (MALL) during package development. It is applicable to a wide range of package types, can locate leaks, and can measure leak flow rates directly.
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