PeptideSynthNJ said:

Compounding pharmacy dose accuracy check for dosing arithmetic: I always verify my first dose from a new vial by weighing it on a milligram scale.

Regarding dosing arithmetic multi-dose vial contamination prevention: after reconstituting, I wipe the vial stopper with a fresh alcohol swab before EVERY single draw. I also never touch the stopper with my fingers and use a new needle for each draw.

Even with bacteriostatic water preservative, contamination is cumulative. One sloppy draw can introduce bacteria that multiply over days. Aseptic technique isn't optional — it's essential for injectable medications.

PeptideSynthNJ said:

Compounding pharmacy dose accuracy check for dosing arithmetic: I always verify my first dose from a new vial by weighing it on a milligram scale.

This answered a question I did not know how to ask. I will report back once I have actually tried it.

Clinical perspective, offered as context rather than as advice.

Ongoing cost tracking for dosing arithmetic — transparency for the community:

Monthly medication cost: $128
Supplies (syringes, BAC water, alcohol swabs): ~$11/month
Janoshik testing: ~$13/month (amortized quarterly)
Lab work: ~$58/month (amortized quarterly)
Total: ~$188/month

Compare to brand Wegovy at $1218/month without insurance. Compounded is roughly 88% cheaper for what I have found to be clinically equivalent medication.

sophie_paris said:

Ongoing cost tracking for dosing arithmetic — transparency for the community: Monthly medication cost: $128 Supplies (syringes, BAC water, alcohol…

This is my experience too, for whatever a second data point is worth. The detail I would add is minor and it is already implied above.

Closing the loop on my own question.

Went back through my own correspondence with an earlier supplier and the warning signs were all there in the replies, weeks before the quality changed. I was reading the product and not the behaviour.