Adding the numbers, since they settle part of this. Two things anyone can check: a state licence number for a 503A, and an FDA outsourcing-facility registration for a 503B. Both are publicly searchable, and a pharmacy unwilling to give you either has answered the question.
If somebody has the primary source to hand I would rather cite it than paraphrase it.
One thing that is still open after rachel_ABQ’s answer:
What actually distinguishes 503A from 503B, in terms of what each may make and from what starting material?
kate.chem said:Two things anyone can check: a state licence number for a 503A, and an FDA outsourcing-facility registration for a 503B.
Adding the part of the answer the thread has not reached. 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.
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The bulks-list asymmetry was the piece I had missed entirely. It explains why one of my two pharmacies is still arguing it can supply and the other simply stopped.
roxy_nash said:Resolution therefore closed the doors unevenly, and the asymmetry follows from the bulks lists.
Agreed, and the enforcement dates were staggered by category — 503A first, 503B a few weeks later — because outsourcing facilities have manufactured inventory and clinic contracts to unwind while a 503A makes to order.