The purpose of bioburden and endotoxin mapping study is to characterize the upstream and downstream steps of drug substance manufacturing process, from WCB vial thaw to bulk drug substance (BDS), with respect to the microbiological indicators of bioburden and endotoxin. The mapping report is a summary of accumulated production lots, usually 20 to 30 lots are acceptable for statistically analysis. 

The microbiological quality of the product can potentially impact overall quality and safety of the product. Note bioburden is the level and type of microorganisms with may be present in raw materials, starting materials, intermediates, or process streams, it is not be considered contamination unless the levels exceed the acceptance criteria. In-process samples and drug substance samples are taken aseptically and submit to QC for testing with established methods, if microbials are detected above acceptable limits, investigation and the organism identification is required to evaluate if they are harmful. During biologics manufacturing process, strict control measures are used to minimize bioburden and endotoxin levels, including, but not limited to, the followings:

• Process equipment and utilities are qualified (e.g., IOQ), and Cleaning-in-Place (CIP) and Steam-in-Place (SIP) of equipment is done as appropriate. Analytical equipment is also qualified prior to use.   

• Use of sterile filters (e.g., 0.1µm, 0.2µm) for process gas and liquid filtration, and perform filter integrity test and system leak detection

• System pressure maintains positive.

• Use closed systems in the process as possible. Manipulation of open containers (e.g., flask culture) is performed in biosafety cabinet (ICH Class 5 or Grade A)

• Cleanroom classification is properly maintained, environment monitoring is performed regularly.

• Raw materials are quality released based on applicable procedures and specifications.

• Single-use systems and consumables are gamma irradiated or autoclaved before use.

Process steps that subjects to bioburden/endotoxin mapping scope is shown in below table. The results of the study are analyzed to demonstrate the manufacturing facility design and operation procedures are adequate for microbial control. If out-of-limit bioburden/endotoxin levels are observed, additional studies will be performed to further characterize the process in order to ensure process effectiveness in bioburden/endotoxin control. In addition, based on the interim reports, the number of sampling points and the established bioburden/endotoxin limits may be adjusted as appropriate.