Which ISO class represents the cleanest environment for compounding sterile preparations?

• A. ISO class 1
• B. ISO class 5
• C. ISO class 7
• D. ISO class 9

Answer: (A)

The cleanest environment for compounding sterile preparations is represented by ISO class 1. This classification indicates an environment where there are no measurable particles, with controlled levels of microorganisms. This level of cleanliness is crucial when creating products that must remain sterile, as any contamination can lead to serious health risks for patients.

ISO class 1 is designed for applications that require the highest level of cleanliness due to the stringent limits on airborne particulate matter and microorganisms. Although ISO class 5 is also a very clean environment, it allows for a small number of particles, specifically up to 3,520 particles per cubic meter of air, making it less clean than ISO class 1. ISO class 7 and ISO class 9 represent environments with even higher allowable particle counts, making them unsuitable for the most sensitive sterile preparations compared to ISO class 1.