Adequate working channel extraction in biocompatibility test

summer

Registered
We received FDA additional information requests for the extration steps to ensure that the working channel was adequately extracted in the biocompatibility test. The submitted test report states that "The extracts were continuously agitated during extraction".

Is there any other steps needed to ensure that the working channel is adequately extracted?
 

planB

Super Moderator
Extraction steps for preparing the samples for what test? What do you mean by "working channel?

Generally, if your lab followed ISO 10993-12 in its current revision, also taking into account your devices nature / duration of exposure and the intended subsequent test, your extraction procedure should be adequate.

HTH,
 

summer

Registered
Thanks for your answer :)

Extraction steps of preparing the samples is for biocompatibility tests. Working channel of the device will come into in-direct contact with patients during normal use. It is used to deliver liquids or as a passage for devices used together to enter the human body.

In ISO 10993-12, we do not find information on the extraction procedure requirements for the extraction step, except for the information provided in section 10.3.6 below. Continuous agitation extraction was used in our sample preparation process. It seems that more detailed information about the extraction steps is needed.

10.3.6 Extractions should be performed with continuous, mechanical agitation or circulation. When extraction under static conditions or intermittent agitation is considered to be appropriate, the method shall be justified, specified and reported. Care should be taken to not to damage the sample or the container.
 

planB

Super Moderator
Here are a couple more questions in case you seek a more specific answer:
  1. What is the duration and nature of exposure of your device?
  2. For what test did you have your device extracted?
  3. What were the actual extraction conditions?
  4. What was the _exact_ FDA request?
  5. Have you forwarded the FDA request to your lab that performed the extraction? If yes, what was the lab's response?
 

summer

Registered
Here are a couple more questions in case you seek a more specific answer:
  1. What is the duration and nature of exposure of your device?
  2. For what test did you have your device extracted?
  3. What were the actual extraction conditions?
  4. What was the _exact_ FDA request?
  5. Have you forwarded the FDA request to your lab that performed the extraction? If yes, what was the lab's response?
1. Nature of exposure: Mucosal membranes, duration of exposure: Limited exposure (A).
2. It is for biocompitability test.
3. Extraction conditions: 50±2℃ for 70±2h, extraction ratio: 6cm²/mL. The extracts were continuously agitated during extraction.
4. The FDA request: The minimum inner diameter of the device was used as the test article for biocompatibility testing. The small size of the sheath can present a potential challenge in the extraction process. However,In the biocompatibility test reports, it is unclear what steps were performed to ensure that the working channel was adequately extracted. Please clarify how the working channel extraction was performed.
5. Yes, we forwarded to the lab. And their response is as follows: The testing lab used a 5ml disposable sterile syringe to inject the extraction medium into the internal cavity to ensure that the extraction solution fully contacted the internal and external surfaces of the test sample. At the end of the extraction, technician used another disposable sterile syringe to remove the extraction solution from the inner cavity and mix it with the remaining extraction solution for use.
 

planB

Super Moderator
You might be in a good position to address FDA concerns by
- emphasising that your chosen extraction conditions exceed the intended contact duration by far, i.e. that you at least performed an exaggerated extraction
- a written statement of your lab as provided above under (5), including a specific statement issued by the lab, such as "Thereby, the testing lab ensured that the working channel was adequately extracted."

HTH,
 

summer

Registered
You might be in a good position to address FDA concerns by
- emphasising that your chosen extraction conditions exceed the intended contact duration by far, i.e. that you at least performed an exaggerated extraction
- a written statement of your lab as provided above under (5), including a specific statement issued by the lab, such as "Thereby, the testing lab ensured that the working channel was adequately extracted."

HTH,

Thank you very much for the reply and providing the very helpful handling method. It helps a lot.

And we are confused about the need to ensure that the volume of the extraction injected into or extracted from the channel by a sterile syringe should be greater than the volume of the channel.
 
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