Taking the question as asked, rather than the general version of 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.
Two pharmacies quoted me last year, one describing itself as 503A and one as 503B, and I assumed 503B just meant bigger until both stopped within weeks of each other.
What I actually want to know is what actually distinguishes 503A from 503B, in terms of what each may make and from what starting material.
I would rather have one careful answer than five confident ones.
Dr.ObesityMed said:Resolution therefore closed the doors unevenly, and the asymmetry follows from the bulks lists.
Agreeing with Dr.ObesityMed, and the qualification matters more than the agreement. Worth adding the genuine exception, because it is real and narrow: a change made for an identified patient where the prescriber determines it produces a significant clinical difference for that patient. A grid of fixed doses offered to everybody is not that, whatever the intake form says.
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Shop Reference Standardshannah_MT said:Two pharmacies quoted me last year, one describing itself as 503A and one as 503B, and I assumed 503B just meant bigger until both stopped within…
Same position here, arrived at the long way round. 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.
Clinical perspective, offered as context rather than as advice.
Compounding pharmacy red flag checklist for compounded supply — if ANY of these apply, find a different source:
- No verifiable physical address
- No pharmacist available for consultation
- COA not available or clearly template/fake
- Prices dramatically below market ($30-40/month = suspicious)
- No prescription required
- Ships without cold pack or temperature control
- No batch/lot numbers on product labeling
- Pushes "research use only" products for human injection
Your health depends on product quality. Don't cut corners on source verification.