How many units within a batch need to be tested to ensure absolute sterility?

To ensure absolute sterility in a batch of compounded sterile preparations, testing every unit is essential. This approach is critical because contamination can occur at any stage during the compounding process, and relying on a sample rather than testing all units can result in undetected non-sterility within the batch.

When every unit is tested, it guarantees that all products meet the sterility assurance level, allowing for more confidence in the safety and efficacy of the compounded sterile preparations. This comprehensive testing aligns with the standards set forth in the USP 797 guidelines, which prioritize patient safety by emphasizing rigorous sterility assurance processes.

Testing just one unit or only the first unit would not provide a reliable indication of the entire batch's sterility, and testing three units, while better than one, still does not ensure the safety of all products. Each unit could potentially have its unique contaminant, and each unit must be verified for sterility to uphold the highest standards in pharmaceutical compounding.