Dr.RheumBOS said:

They are two different exemptions from the same federal requirements and they buy different things.

GMP compliance checklist relevant to compounded supply compounding quality:

• Clean room environment with HEPA filtration
• Environmental monitoring (viable and non-viable)
• Personnel training and competency assessment
• Validated analytical methods for testing
• Stability testing program
• Complete batch records and traceability
• Quality management system with deviation handling

A 503B pharmacy following cGMP should be able to answer questions about ALL of these if you ask. Don't be afraid to ask — it's your health.

Following on from Dr.CardioMD — and this may be the naive question:

Why a shortage listing created a legal pathway at all, since a shortage is a supply fact rather than a permission?

TirzTom said:

GMP compliance checklist relevant to compounded supply compounding quality: Clean room environment with HEPA filtration Environmental monitoring…

Adding the part of the answer the thread has not reached. Denials are usually procedural rather than clinical, and the order that works reflects that. Get the denial reason in writing, because it names the criterion you failed. Then supply the documentation that criterion asks for — usually documented BMI with a comorbidity, or a failed prior therapy. Then appeal, and ask for a peer-to-peer review, because a prescriber talking to a reviewing clinician resolves a large fraction of denials that written appeals do not. Manufacturer copay assistance is separate and applies mainly to commercial insurance, and patient assistance programmes are means-tested rather than a discount.

Closing the loop on my own question.

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.

VanRx_Mike said:

Denials are usually procedural rather than clinical, and the order that works reflects that.

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.