we need to provide a method for sterility testing of sterile transdermal patches with special protein collagen layer.
We cannot find any test method in the US EP and BP. I am afraid that apart from that classical test or sterility are not applicable beacause the collagen layer causes turbidity in thioglicolate medium.
we think that if find a way to remove thye collgane layer the problem with the turbidty could disappear. But we do not know how to do this!

If sterility is your objective - I dont see how you can eliminate the collagen layer you mention.

why not culture the entire patch and streak thio on TSa for growth.

The following product was cleared for 510(k) and determined substantially equivalent to their predicate by using USP XXIV Chapter 71 test methods.

DermADAPTTM Wound Dressing - Pegasus Biologics, Inc.


The following research products also used Chapter 71 test methods...


Mouse Collagen IV - Trevigen


Q-Col® High Performance Serum-Free Cell Attachment


3-D Culture Matrix™ Rat Collagen I - Cultrex


Cultrex® Rat Collagen I - Trevigen

try using collagenase... that would take care of the collagen but you'll need to demonstrate that the collagenase is sterile and that it doesn't inhibit growth.