Dr.ObesityLA said:

The mechanism that matters here is not stomach emptying, it is central.

I read this differently from Dr.ObesityLA, on substance rather than tone. The trial means are being read too generously in this thread. STEP populations were selected, supported, and titrated by protocol, and the real-world curves are consistently a few points worse. That difference is not noise, it is what happens when you remove the study infrastructure.

That is the short version; the long version is somebody else's post.

Adding the numbers, since they settle part of this. Worth knowing that the injection site changes very little. Abdomen, thigh and upper arm are bioequivalent for semaglutide, so a site change is not a plausible explanation for a bad week.

LabKate said:

The trial means are being read too generously in this thread.

Coming at LabKate’s question from a different direction. The shortage clause is the answer to the second question and it is a subtraction rather than an addition. Both exemptions forbid compounding something that is essentially a copy of a commercially available approved product. A product FDA has listed as in shortage is not treated as commercially available, so listing removed the objection that otherwise blocked compounding. It never created a permission; it withdrew a prohibition, which is why it evaporated the moment the supply fact changed.

A narrower follow-up, since the general answer is now clear:

What actually distinguishes 503A from 503B, in terms of what each may make and from what starting material?

OP back with an update, since a thread like this is useless without one.

Following this thread I went back and re-read the extension data properly. The point about trough rather than peak explains the pattern I was seeing on day six, which I had been blaming on the vial.