Reference
GLP-1 medicines
Regulatory status and half-life for the GLP-1 medicines in the VialPal library, taken from the FDA labels and published trials, plus what the FDA says about compounded and “research” versions. This page does not give doses or schedules: those come from your prescriber, your pharmacy or the product label.
Compounded GLP-1 drugs are not FDA-approved, and the FDA does not review them for safety, effectiveness or quality before they are sold. Retatrutide is not part of any FDA-approved drug and, according to the FDA, cannot be used in compounding under federal law.
The compounds
| Compound | Acts on | Status | Half-life |
|---|---|---|---|
| Semaglutide | GLP-1 | FDA-approved as Ozempic, Wegovy, Rybelsus. Compounded versions are not. | ~7 days |
| Tirzepatide | GIP and GLP-1 | FDA-approved as Mounjaro, Zepbound. Compounded versions are not. | ~5 days |
| Liraglutide | GLP-1 | FDA-approved as Saxenda, Victoza. Compounded versions are not. | ~13 hours |
| Retatrutide | GIP, GLP-1 and glucagon | Not part of any FDA-approved drug. Investigational. | ~6 days |
Each compound’s page lists the label or study its half-life comes from, and its storage guidance.
Brand-name, compounded and “research” versions
Brand-name products such as Ozempic, Wegovy, Mounjaro and Zepbound are FDA-approved: the agency reviewed their safety, effectiveness and manufacturing before they were sold.
Compounded versions are made by a state-licensed pharmacy for an individual prescription, or by an outsourcing facility. The FDA says they should be used only when a patient’s needs cannot be met by an approved drug, and that a company claiming its compounded drug is the same as an approved one is a red flag. It also warns that salt forms such as semaglutide sodium are a different active ingredient from the approved drug.
“For research” vials of semaglutide, tirzepatide or retatrutide sold to consumers are unapproved drugs. The FDA has warned companies for selling them illegally and calls them of unknown quality.
Where vials go wrong
The FDA has received adverse-event reports, some needing hospital care, that may be related to people measuring and self-administering the wrong amount of compounded semaglutide, and in some cases to clinicians miscalculating it. Turning a vial’s strength into syringe units is an easy step to get wrong. The reconstitution calculator shows that arithmetic step by step for the numbers on your own label, so you can check it against your pharmacy’s instructions.
The FDA also recommends discarding a multi-dose vial 28 days after first use, even if medicine remains and even if the compounder’s instructions say otherwise, and not using an injectable GLP-1 that arrives warm. VialPal dates every log entry against its vial, so the first entry shows when you started that vial.
Guides that apply
- How to Reconstitute a Peptide Vial (and Check Your Own Maths)
What reconstitution actually is, the two-step arithmetic behind every draw, and how to verify the number you got before you trust it.
- Insulin Syringe Units vs mL: How to Read the Barrel
Why "units" are a volume and not a dose, what U-100 means, how 0.3/0.5/1.0 mL syringes differ, and the mistake that causes ten-fold errors.
- How Much Bacteriostatic Water Should You Add?
There is no correct diluent volume — only trade-offs. How to pick one by working backwards from the dose you want to be able to measure.
- Peptide Storage: Before and After Reconstitution
Lyophilised powder and peptide in solution have completely different storage requirements. What degrades them, and the handling errors that cost the most potency.
- Why Your Peptide Calculator and Mine Disagree
Two calculators, the same vial, different answers. The arithmetic is never the problem — it is the syringe scale, the unit assumptions and what "volume" is being asked for. How to find which one is wrong.
Source
U.S. Food and Drug Administration, FDA’s Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Half-life figures are cited on each compound’s page. Informational only, not medical advice.