Is it normal for the powder to not fully dissolve

HPLC_Greg said:

The shortage clause is the answer to the second question and it is a subtraction rather than an addition.

Filing a mild objection. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit. 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.

jason_sac26 said:

My pharmacy stopped supplying with three weeks notice and a letter that explained nothing, so I went and read the statute.

I have been on both brand and compounded, and in the context of compounded supply, my experience has been equivalent with both. The key is finding a reliable 503B pharmacy with independent testing.

BethLabQueen said:

A research-chemical supplier selling lyophilised powder labelled research use only is not compounding and is not claiming to.

Compounding pharmacy licensing verification for compounded supply: before ordering, verify your pharmacy's credentials:

1. State Board of Pharmacy license — check on your state BOP website
2. FDA registration (for 503B) — check on fda.gov
3. DEA registration if handling controlled substances
4. PCAB accreditation — voluntary but demonstrates commitment to quality
5. USP <797>/<800> compliance for sterile compounding

This takes 10 minutes of research and could save you from receiving substandard or unsafe medication.

One thing that is still open after HealthEcon_DC’s answer:

What actually distinguishes 503A from 503B, in terms of what each may make and from what starting material?

OP back with an update, since a thread like this is useless without one.

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.