ASTM E 3425 : 2024

1.1This guide provides guidance on the development of test methods that apply automated membrane microscopy (AMM) to the measurement of extraneous solid insoluble particulate matter present in parenteral pharmaceutical manufacturing processes and drug products. For the validation requirements for AMM test methods, see Practice E3411.

1.2In an AMM test method, a test liquid containing suspended particles is filtered through a membrane filter, the particles are retained on the surface of the membrane filter, the membrane filter surface is imaged with an optical microscope and digital camera, and application of image analysis software determines particle count and particle sizes.

1.3AMM test methods may be applied to the measurement of the commonly defined size categories of subvisible (<100 µm) or visible (≥100 µm) or both particulate matter present during any stage of the manufacturing of parenteral pharmaceuticals.

1.4The test liquid characterized by an AMM test method may be a process fluid, drug substance or drug product, or liquid extracts from the surfaces of processing equipment, drug containers, delivery devices, and components thereof.

1.5This guide does not apply to the characterization of particles inherent to parenteral suspensions (for example, cells, protein aggregates, or vaccine adjuvants) or the characterization of liquid droplets (for example, silicone oil).

1.6Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.7This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.8This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.