Batch-to-batch purity variation — acceptable ranges

Sent my compounded semaglutide (5mg/2mL vial from a 503A pharmacy) to Janoshik for third-party testing. Just got the results back:

• Identity: Confirmed semaglutide
• Purity (HPLC): 82.3%
• Related substances: 17.7% degradation products

The pharmacy's own COA claims 98.2% purity. So either they're lying or something degraded between compounding and testing.

Is 82% acceptable? Should I be concerned? I've been injecting this for 3 weeks already. 😰

82% is NOT acceptable. Full stop.

USP monograph standards for compounded injectables generally require potency between 90-110% of label claim, with most pharmacies targeting 97-103%. The FDA has cited pharmacies for products testing below 90%.

17.7% degradation products is alarming. That means nearly 1 in 5 molecules in your vial is not semaglutide — it's a breakdown product of unknown biological activity.

Questions to consider:

1. How did you store the vial before sending to Janoshik?
2. How was it shipped? (Temperature excursion during transit could cause degradation)
3. When was the compounding date vs. your test date?

These factors matter because the low purity could be a storage/shipping artifact rather than a compounding quality issue. But it could also mean the pharmacy is using low-grade API.

Good questions. I stored it refrigerated (2-8°C) the entire time. Shipped to Janoshik with cold packs via express courier — 2 day transit. Compounding date was Feb 12, I sent the sample March 1, so less than 3 weeks old. BUD on the vial says 90 days.

I don't think storage is the issue here.

Previously posted:

17.7% degradation products is alarming. That means nearly 1 in 5 molecules in your vial is not semaglutide

Let me add some nuance here. "Related substances" on an HPLC readout don't always mean dangerous degradation products. Some could be:

• Des-amino variants (minor structural differences)
• Oxidized forms (common with peptides)
• Aggregates that partially resolved on the column

That said, 82% is still well below any reasonable standard. For context, Novo Nordisk's branded Ozempic and Wegovy typically test at 98-101% purity. Research-grade semaglutide from reputable suppliers is usually ≥95%.

I'd stop using this vial immediately and contact the pharmacy. Ask them to test a retained sample from your batch (they're required to keep one). If their retained sample also tests low, you have a serious quality issue. If theirs tests fine, then something happened during shipping to Janoshik.

Wait, I've been using the same pharmacy. Should I be worried?? I've been on their compounded sema for 2 months and haven't had any side effects beyond the normal nausea. Does low purity mean it's dangerous or just less effective?