FDA warning letter to ProRx LLC over sterility and quality deficiencies

The FDA issued a warning letter dated April 7, 2026 to ProRx LLC, a registered 503B outsourcing facility in Exton, Pennsylvania, citing "serious deficiencies in your practices for producing drug products intended or expected to be sterile, which put patients at risk" ^[1]. The letter also says ProRx compounded tirzepatide using bulk drug substance at a time when it was not legally permitted to do so ^[1].

The warning letter (WL # 723704) follows an FDA inspection that ran from September 9 to September 19, 2025 ^[1]. The agency issued a Form FDA 483 on September 19, 2025, and an amended 483 on October 10, 2025, then reviewed the company's October 24, 2025 response and later correspondence dated February 13, 2026 ^[1]. ProRx first registered as an outsourcing facility on April 27, 2022, and most recently on February 20, 2026 ^[1].

What the FDA found

On October 15, 2025, ProRx began a voluntary recall of Lot PRORX08062025-3 of Tirzepatide Injection 27mg/3mL in 3mL multidose vials, plus "various lots of Semaglutide Injection multidose vials in multiple strengths" that were still within expiry, because of a lack of sterility assurance ^[1].

The FDA's sterility findings are detailed. Investigators said the firm did not adequately evaluate product or take corrective action after microbial contamination was recovered inside the ISO 5 production area, and instead "approved and distributed drug products" made when colony-forming units were found on ISO 5 operator gloves and settle plates ^[1]. An operator blocked first air by putting gloved hands or forearms directly over an open tray of stoppers meant to be sterile ^[1]. Materials moved from the ISO 7 cleanroom into the ISO 5 workstation were not surface-disinfected, and a non-sterilized scissor stored in the ISO 7 area — only wiped before use — was used to cut open a bag of stoppers during filling ^[1]. The floor of the ISO 7 buffer room showed "significant visible sporadic discoloration, the cause of which remains unknown" ^[1].

Separately, the FDA said ProRx compounded vials of Tirzepatide 72MG/4ML and Tirzepatide 45MG/2.5ML from bulk tirzepatide, which does not appear on the 503B bulks list and was not on the drug shortage list at the time of compounding, distribution and dispensing ^[1]. Labels on several products, including Tirzepatide Injection 45mg/2.5mL, Nicotinamide Adenine Dinucleotide Injection 1200mg and Glutathione Injection 2000mg, were missing the required "Not for Resale" statement ^[1]. The firm's adverse event reporting procedures lacked an adequate definition of a "serious" adverse event and did not require follow-up reports within 15 calendar days ^[1]. The FDA also cited five current good manufacturing practice violations, including failure to thoroughly investigate batch discrepancies and failure to establish adequate environmental monitoring and disinfection systems ^[1].

Why it matters for patients

Compounded semaglutide and tirzepatide are not FDA-approved products, and the letter states plainly that ProRx has no FDA-approved applications on file for anything it compounds ^[1]. When a sterile injectable is made without sterility assurance, the risk is contamination of a product that goes directly under the skin — which is why the October 2025 recall covered vials that had not yet expired ^[1].

The tirzepatide finding reflects a broader rule change. After the FDA determined the Mounjaro and Zepbound shortage had ended, 503B outsourcing facilities faced a March 19 deadline to stop compounding tirzepatide, and Eli Lilly has sued compounders it accused of continuing anyway ^[2]. In April 2025, a different outsourcer, Houston-based Empower Pharma, received its own warning letter over sterility and labeling problems after an August inspection ^[2]. The sources provided here do not document ProRx's role in any Lilly litigation, so that connection is not established by this reporting.

What happens next

A warning letter is not a ban. It is the FDA's formal notice that it considers products adulterated and misbranded, and companies are typically expected to respond with corrective actions. The published text of the ProRx letter available here is cut off before any response deadline or penalty discussion, so the timeline for ProRx's next steps, and whether further recalls or enforcement follow, is not yet known ^[1].