Where Compounded Tirzepatide API Comes From: 503A/503B

A GLP1 Forum Escrow guide for buyers. Educational and research reference only, not medical advice.

503A and 503B compounders in brief

The labels 503A and 503B refer to sections of US law that govern licensed compounding pharmacies, which prepare medications tailored to a prescription. The two differ mainly in scale. A 503A pharmacy fills prescriptions for individual patients, while a 503B facility is permitted to produce larger batches that it supplies to hospitals and other healthcare providers.

Compounders were able to make tirzepatide because the drug was listed as being in shortage, which allowed them to prepare and dispense it to patients. That changed when the FDA formally determined on December 19, 2024 that the tirzepatide API shortage had ended. Under that decision, compounding of tirzepatide by these pharmacies was set to wind down in February and March 2025, leaving the branded prescription products Mounjaro and Zepbound as the approved route for patients.

Where compounders get their raw material

A compliant 503A or 503B pharmacy has to buy its tirzepatide API from manufacturers or resellers that are registered with the FDA (source). The registration data tell a clear story about origin: production of the raw tirzepatide powder takes place entirely in China. The US-approved labelers act as wholesale resellers of that material. One further labeler is based in India, though as of December 2024 we had not seen its product in the US.

When asked, Red Rock Pharmacy, a 503A compounder in Utah, shared the manufacturer certificates of analysis shown below. They confirm that Red Rock buys from at least two suppliers, Genohope and Avlantis, both of which appear on the FDA’s list of registered tirzepatide labelers.

Mapping the registered labelers

The chart groups the registered labeler names by country and by their FDA market category. Two points stand out. China dominates as the source of bulk tirzepatide API, and only 7 of the listed labelers sell tirzepatide in quantities of 1kg or more. The remainder are most likely reselling raw powder manufactured elsewhere.

How the labeler count has grown

Since January 2023 the running total of registered tirzepatide labelers has climbed steadily, and China accounts for most of that growth. US entries stay few in number, which fits their position as intermediaries rather than original producers. Corden Pharma, operating under license from Eli Lilly, is the only company known to actually manufacture tirzepatide API inside the US.

Base powder, not lyophilized product

We also asked Red Rock Pharmacy which form of tirzepatide it starts from. Its reply, reproduced below, states that it compounds from the tirzepatide base form supplied as raw powder and does not buy or use lyophilized tirzepatide. Our working assumption is that the other large compounding operations, such as Hallandale and Empower, take the same approach, although we have not confirmed this with them.

This background helps when reading a certificate of analysis on a GLP1 Forum Escrow listing: it shows where bulk material originates and why the manufacturer named on a report matters.

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