Posting this because the summary going around does not say what the paper says, and the difference matters for how people here are using it.
Resolution therefore closed the doors unevenly, and the asymmetry follows from the bulks lists. For 503B the shortage clause was the only route to these molecules, so that route shut completely. A 503A pharmacy can still argue a doorway via "component of an approved drug" — but only for the substance in the form present in the approved product, which is exactly where the base-versus-salt argument lives, and it does nothing about the copy restriction, which came back into force on resolution.
Where I think it is weakest: the completion rate deserves as much attention as the headline, because a large effect among those who finished is a different claim from a large effect among those enrolled.
The narrow version of the question is what actually distinguishes 503A from 503B, in terms of what each may make and from what starting material. I have searched first, so if this is covered somewhere point me at it and I will read it.
Figures above are from the primary publication rather than the press summary. If a number here disagrees with one you have, post yours and we will work out which of us is reading a secondary source.
rick_sfbay said:Resolution therefore closed the doors unevenly, and the asymmetry follows from the bulks lists.
That is correct as far as it goes, and here is where it stops going. 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.
rick_sfbay said:Resolution therefore closed the doors unevenly, and the asymmetry follows from the bulks lists.
Pushing back on rick_sfbay here. A research-chemical supplier selling lyophilised powder labelled research use only is not compounding and is not claiming to. It is a different legal universe with no pharmacy oversight, no patient relationship and no content guarantee, and conflating the two in these threads helps nobody.
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Shop Reference StandardsAnswering the narrow version, because the broad one does not have a single answer. They are two different exemptions from the same federal requirements and they buy different things. A 503A pharmacy is regulated primarily by the state board, needs a patient-specific prescription, is exempt from CGMP, and may use a bulk substance that has a USP monograph, is a component of an approved drug, or appears on the 503A bulks list — three independent doorways. A 503B outsourcing facility registers with the FDA, is inspected on a risk basis, must comply with CGMP, may compound for office stock without a patient-specific prescription, and has one doorway to a permitted bulk substance: the 503B bulks list, or the drug shortage list.
Dr.MetabolicMD said:The shortage clause is the answer to the second question and it is a subtraction rather than an addition.
Same pattern here, and in the same order.