Environment for Mixing and Holding tanks

Hello everyone, hope you are doing good.
Can someone please suggest the class or grade environment required for surroundings of mixing tanks and filteration tanks in manufacturing of sterile injectable? Someone told me that Grade C is enough for both but someone else told me that filteration tanks need Grade B environment. Any help is appericiated.


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Hello Prakhar,

Grade C is enough for mixing and compounding of sterile injection, unless it is an aseptic preparation, which must be within grade A environment, or if a risk management activity concludes that grade B or A is needed (e.g. contamination control strategy).

I don’t fully understand what you are referring to as filtration tanks, since sterile filtration is usually done in a filtration system along the pipeline or terminal filters at the filling machines. It is done this way to make sure all effluents are sterile, meaning that all fluid must have passed through the sterilizing filter.
My understanding of a filtration tank is more of those used to treat water in a PW or WFI generation system, which are not intended to render the fluid sterile.

My suggestion is that you use a risk based approach and document it to make an informed decision regards the environment of the filtration tank. Some ideas to consider for this risk assessment:

  • Is the filtration tank used to sterilize fluids?
  • Is the filtration tank open to the environment at any given moment?
  • Is the product within the tank terminally sterilized or aseptically filled?

I hope these suggestions are useful.