these slides. But you can see this particular product, the old product, was all below this level.
May I have the next slide, please? However, with the reference product again, Synthroid, many of the levels did go well up, not all but a few. What we've seen in both studies is a subset. There appears to be a subset of individuals who take the reference product, in this case Synthroid, who uniformly jump up with the TSH levels and that may be part of the explanation that many of the clinicians have talked about today.
May I have the next slide, please? Let me give you a possible explanation for this subset. This is my hypothesis. These are the in vitro dissolution times for the reference product. This was the older Synthroid product. I can't say whether this is relative to today's product or not, but I simply want to give you an example of why these TSH levels changed.
About 50 percent of the drug is not dissolved in this in vitro method at about one hour. On the other hand, the other products that I've just talked to you about, almost all of them follow the current USP dissolution definitions, which means that about 80 to 90