As promised, here are my Janoshik Analytical test results for two different compounded tirzepatide sources I've been using. I paid for these out of pocket (~$120/test) because I wanted to know what I'm actually injecting.
Test Results:
| Parameter | Source A (503B pharmacy) | Source B (online compound) | Expected |
|---|---|---|---|
| Peptide identity | Confirmed tirzepatide | Confirmed tirzepatide | Tirzepatide |
| Purity (HPLC) | 97.8% | 91.2% | ≥95% |
| Concentration (labeled 10mg/mL) | 9.6 mg/mL | 7.8 mg/mL | 10.0 mg/mL |
| Endotoxin | <0.5 EU/mL | Not tested | <5.0 EU/mL |
| Sterility | Pass | Not tested | Pass |
Analysis:
- Source A (503B): Good results. Purity is within acceptable range. Concentration is slightly under-dosed (96% of label) which is within typical pharmaceutical tolerance. Endotoxin and sterility passed.
- Source B: Concerning. Purity at 91.2% means ~9% impurities/degradation products. Concentration is only 78% of labeled dose — you'd need to inject 28% more volume to get the advertised dose. No endotoxin or sterility testing available, which is a red flag.
I am NOT naming the specific sources — please don't ask. This post is about demonstrating WHY third-party testing matters, not about promoting or bashing specific vendors.
This is incredibly valuable data, thank you RegAffairsDC. The underdosing on Source B is honestly scary. If someone is titrating based on their perceived dose and they're actually getting 22% less, they could think the medication isn't working when really they're just underdosed.
Also the lack of endotoxin and sterility testing from Source B is... really not ok for something you're injecting subcutaneously.
Pharmacist perspective: these results illustrate exactly why 503A vs 503B distinction matters.
- 503B outsourcing facilities are registered with the FDA, subject to CGMP (Current Good Manufacturing Practice) requirements, and must pass FDA inspections. They're essentially small-scale pharmaceutical manufacturers.
- 503A pharmacies compound on a per-patient basis with a valid prescription. Quality varies enormously. Some are excellent, some are... not.
- Unregistered/gray market sources are a complete wildcard.
Source A's results are consistent with what I'd expect from a reputable 503B facility. Source B's results are consistent with what I'd expect from a facility that isn't following proper quality controls.
The purity difference (97.8% vs 91.2%) matters more than people think. Those 9% impurities could be degradation products, synthesis byproducts, or other peptides. Some of those could cause immune reactions or injection site issues.
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View ResultsI appreciate the data but can we also acknowledge the elephant in the room? Compounded tirzepatide exists in a legal gray area right now. The FDA's position on compounding GLP-1s has been evolving and there's active litigation. People should be aware of the regulatory landscape, not just the chemistry.
I'm not anti-compound — I understand the access/cost issues that drive people there. But informed consent requires knowing the full picture.
I pay $200/month for compounded tirz. Brand Zepbound would be $1,059/month without insurance, and my insurance doesn't cover ANY weight loss medications.
Yes, compounded is riskier. Yes, quality varies. But for many of us the choice isn't "brand vs compound" — it's "compound vs nothing." And I'd rather take tested compound tirz than stay at BMI 42 with sleep apnea, prediabetes, and fatty liver.
Risk is relative.