Pressure difference | Cross Contamination

Greetings, i have one question, and i need a fast answer on reference.

We are designing blister and carton packing facility to other country (contract) for oncological products and we designed the lower pressure in the blistering room and higher pressure rooms (mainly airlocks) around the blistering room, to make that room ‘isolated’.

People preparing technological ‘writtings’ on the facility is confused on such pressure difference as they are used to “everything goes to the corridor” model.

So i need to support our design on some specific GMP, WHO, ISPE guideline to stop this discussion and to move on. Because i cant say “gmp told me so”. I need reference.

Thanks in advance.

[i]Working document QAS/02.048/Rev.2



will this do the job?

What you have done is a right practice. Always when oncology products when exposed to certain operation that place must be provided by negetive pressure. In this case your Blister packing room will have a negetive pressure and your airlocks will have higher pressure. Make sure that you have a pressure difference of 10-15 pascals between them so that air flow is from airlocks towards the blister packing room.

Secondly you have to maintain a higher pressure than your common corridor or working corridor where your air-lock opens. People entering into bister area must enter from a low pressure corridor into high pressure airlock. This provides a safety machanism that no small dust of oncology product escapes into your common corridors and cause hazard. The HVAC at blister is connected to a scrubber so that fine dust from oncology product is directly going into scrubber with out causing any environmental hazard to animal and human lives.


I agree with the above - it’s one of the common ways of designing GMP-set ups, especially applicable for extra sensitive or dangerous substances.
It is also written about in the Easy guide to HVAC Validation, available on Ask About Validation.

Good luck with the rationals!

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Dear Prasad

We are preparing opthalmic area in this regard I require validation protocols.


[quote=Muqeet76]Dear Prasad

We are preparing opthalmic area in this regard I require validation protocols.


Require is not the right word you have used. Also your reply has nothing to do with this topic.

Hi Muqeet,
Do you need validation documents?
Can you make a list?
Do write here. Whole world will see your post and help comes right away.


He that does not ask will never know the power of knowledge.

Dear Prasad,

In order to convince your peers you better use local HSE regulations specific to high potency substances. These HSE guidance are written to protect the workforce and environment from being contaminated with a high active substance.

You probably will not find an answer in any of the GMP guidances, because in these guidances the final product is protected rather than the workforce or the environment.

To this end, producing high active substances under GMP conditions is often contradictory to HSE conditions, so one needs to balance the risks carefully.

Your idea of using pressure traps to isolate the area in which the high potency substances are being handled is a good idea and often used in the design of clean room areas. You could also consider to work in special isolators or RABS for certain parts of the process.

Kind regards,

Michiel Rook,
Global ConSeptS - Consultancy

Thanks regarding your suggestions and comments.