However, most drug products contain components that change the surface tension of water. This may alter integrity test results. Delays in production and product release caused by false negative test results can be minimized by drug product-based integrity testing. To ensure product sterility and regulatory compliance, membrane filters must be integrity tested after filtration of a drug product. Membrane manufacturers supply integrity test specifications based on the use of water or alcohol as the wetting solution.
Integrity testing is highly dependent on the physical characteristics of the wetting solution.
Even small changes to the test solution can substantially alter the integrity test results. When physical characteristics of the wetting solution alter integrity test results, there are two options available. The drug product must either be completely flushed out to fully wet the membrane with a solvent of known integrity test values or the effect of the drug product on integrity test results must be determined. Completely flushing the drug product from the membrane can be time consuming and costly. Also, regardless of the volume passed through the filter, some components may bind to the membrane and not readily flush out.