Which of the following is an appropriate method of sterility testing during compounding?

Terminal filtration by membrane filtration is a widely accepted method for ensuring sterility during compounding because it allows the removal of microorganisms from the solution without having to expose the product to heat, which could potentially alter its properties. This method involves passing the compounded sterile solution through a filter with a pore size small enough to retain bacteria and fungi, thus ensuring that the final product is free from contamination.

Membrane filtration is particularly advantageous for heat-sensitive preparations, such as certain biologics or intravenous solutions, where heat sterilization (such as autoclaving) would not be feasible. This technique is part of quality control measures to verify that the compounding environment and processes are effective in producing a sterile product.

In contrast to effective methods of sterility testing, methods like direct inoculation into open environments can introduce contaminants rather than eliminate them, and centrifugation does not adequately remove microbes from the solution. Heat sterilization is a valid method for achieving sterility but is not typically categorized as a method for testing sterility after compounding, making terminal filtration the preferred and appropriate choice in this context.