Pharmaceutical container/closure integrity. VI: A report on the utility of liquid tracer methods for evaluating the microbial barrier properties of pharmaceutical packaging
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Published on: October 17, 2013
1Division of Pharmaceutics, College of Pharmacy, University of Iowa, Iowa City 52242, USA.
Abstract:
The relationship between a liquid tracer package leak test (Mg ion ingress) and microbial immersion challenge test was demonstrated by direct and indirect correlation techniques. Rubber-stoppered glass vials with micropipette leaks were evaluated by a helium leak rate method, filled with broth, sterilized, and immersed in a bath containing microorganisms (E. coli/B. diminuta) and liquid tracer (Mg ions). After exposure and incubation, each unit was evaluated for liquid tracer ingress by atomic absorption spectrophotometry and for microbial ingress by visual inspection and blood agar streaking. Two hundred and eighty sterile broth-filled test units were challenged with microorganisms and liquid tracer. One hundred and fourteen units showed neither liquid tracer nor microbial ingress. One hundred and eight units were positive for both microbial and liquid tracer ingress. No test units were positive for microbial ingress but not for liquid tracer ingress. Fifty-eight units were positive for liquid tracer ingress but failed to show microbial ingress. Logistical regression was used to demonstrate that the probability of liquid tracer ingress was greater than microbial ingress at all leak sizes. The results indicate that the liquid tracer method studied herein was a useful indicator of the microbial barrier properties of pharmaceutical packaging. Additionally, the results support the contention that liquid penetration of a leak is required for microbial ingress.
Insights
A liquid tracer test effectively indicates microbial barrier integrity in pharmaceutical packaging. This Mg ion ingress test is a reliable indicator, as liquid penetration is necessary for microbial ingress.
Area of Science:
- Pharmaceutical Science
- Microbiology
- Materials Science
Background:
- Pharmaceutical packaging integrity is crucial for product safety and efficacy.
- Microbial ingress into packaging can lead to product contamination and spoilage.
- Reliable methods are needed to assess the microbial barrier properties of packaging.
Purpose of the Study:
- To evaluate the relationship between liquid tracer ingress (Mg ion) and microbial ingress in rubber-stoppered glass vials.
- To determine if liquid tracer ingress can serve as an indicator for microbial barrier performance.
- To support the understanding that liquid penetration precedes microbial ingress.
Main Methods:
- Rubber-stoppered glass vials with controlled leaks were used.
- Vials were filled with broth, sterilized, and immersed in a microbial and liquid tracer (Mg ion) bath.
- Ingress was assessed using atomic absorption spectrophotometry for liquid tracer and visual/cultural methods for microbes.
- Helium leak rate method was used for initial leak evaluation.
Main Results:
- 108 out of 280 units showed ingress of both liquid tracer and microorganisms.
- No units showed microbial ingress without liquid tracer ingress.
- 58 units showed liquid tracer ingress but no microbial ingress.
- Logistical regression indicated liquid tracer ingress probability exceeded microbial ingress probability across all leak sizes.
Conclusions:
- The liquid tracer ingress test is a valuable indicator of the microbial barrier properties of pharmaceutical packaging.
- The study supports the principle that liquid penetration through a leak is a prerequisite for microbial ingress.
- This Mg ion ingress method offers a reliable alternative for assessing packaging seal integrity against microbial contamination.
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