This one has a reasonably settled answer, so here it is. 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.ReproEndo said:

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

That is correct as far as it goes, and here is where it stops going. Freezing is the one to avoid, and freeze-thaw more so. Ice-crystal formation and the concentration changes at the phase boundary drive aggregation, and aggregated peptide does not recover on thawing. A vial that has been frozen and thawed is not rescued by returning it to the fridge.

Happy to go further on any of that.

MikeFit_NJ said:

A shipment sat in a depot over a bank holiday weekend and arrived warm, and I cannot find a straight answer about whether it is still usable.

Can confirm the pattern MikeFit_NJ describes. 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.

From the other side of the consultation, briefly.

Cold chain shipping for storage and cold: my last order arrived with the cold pack completely melted and the vial at room temperature. I contacted the vendor and they reshipped with better insulation.

What to look for in shipping: styrofoam inner container with ice packs. If your peptide arrives warm, contact the vendor immediately. Don't assume it's still good.