bioequivalence guidance on potassium chloride modified release tablets and capsules and that's listed up on my slide. I have to say that the second one for levothyroxine sodium tablets refers only to the bioavailability of those products. It does not address the bioequivalence. There seems to be some confusion amongst a variety of industry people, as well as some of the public comment people, that that in some way was supposed to describe bioequivalence policy for levothyroxine. That's not the case. It's strictly a bioavailability guidance, as stated in the title.
Just a short list of some products that might be considered as endogenous substances which may involve special problems in doing bioavailability and bioequivalence. Estrogens, for example, testosterone, progesterone, calcitriol, and someone suggested to me that ‑‑ I wasn't even aware of this. Someone who had worked on the NDA said ursidiol. Also, some other products which are not given orally but are given as parenteral non-solution products, such as insulin and human growth hormone, could be said to have some of the same considerations.