Awesome; thanks for the studies. I searched for thiamine HCl specifically, so I hope pyrophosphate applies well-enough.
Do you think an avoidance of the first-pass metabolism through topical absorption would still benefit the liver, similar to how you've said oral K2 is probably more effective at lowering liver inflammation, or do you think oral is the way to go?
Some of the studies I sent you are with thiamine Hcl. It seems less effective than TPP but still helps a lot. A dose 2-3 higher than the TPP dose used in the studies should give the same effects as TPP.
If you are targeting the liver then oral is the way to go. If you want systemic upregulation of PDH then topical is probably better. Or you can use both methods for optimal results.