503B outsourcing facility: definition, 503A vs 503B, and what FDA cites

A 503B outsourcing facility is a sterile compounding facility that elects to register with FDA under section 503B of the Federal Food, Drug, and Cosmetic Act, compounds under current good manufacturing practice, and may supply hospitals and clinics without a prescription for an identified patient. Section 503B came from the Drug Quality and Security Act, signed on November 27, 2013.

On top of the definition, you get the Atlas Form 483 record (release of August 15, 2026) for 18 facilities on FDA's registered outsourcing facility list, current as of October 29, 2026: 74 Form 483s and 457 observations, issued from 2013 to May 2026.

Key facts:

• Registration under section 503B is voluntary; a facility becomes an outsourcing facility by electing to register, then renews each year between October 1 and December 31.
• An outsourcing facility must meet CGMP under 21 CFR parts 210 and 211, while a 503A pharmacy is exempt from those rules.
• Each outsourcing facility reports every drug it compounded to FDA twice a year, in June and in December, under section 503B(b)(2).
• FDA's registered outsourcing facility list held 100 facilities as of October 29, 2026.
• In the Atlas record, 21 CFR 211.113 (sterile process control) appears on 56 of 74 Form 483s at 18 registered facilities, or 76%.
• 14 of those 18 facilities received a 211.113 citation on two or more separate Form 483s.

What is a 503B outsourcing facility?

A 503B outsourcing facility, often called a 503B pharmacy, is a facility at one geographic location that compounds sterile drugs, has elected to register with FDA as an outsourcing facility, and complies with every requirement of section 503B. That is the statutory definition in section 503B(d)(4). The facility does not have to be a licensed pharmacy, but compounding must take place under the direct supervision of a licensed pharmacist.

Registration brings three federal exemptions. A 503B drug does not need an approved application under section 505, is exempt from the adequate-directions labeling rule in 502(f)(1), and is exempt from the drug supply chain tracing rules in section 582. CGMP still applies. The facility stays subject to section 501(a)(2)(B), so FDA investigators inspect it against 21 CFR part 211, the same CGMP regulation for finished pharmaceuticals that drug manufacturers follow. FDA's CGMP guidance for outsourcing facilities explains how the agency applies those rules to compounders.

Buyers should know two more limits. Section 503B(a)(5) bars a 503B drug that is essentially a copy of an approved drug, unless the drug is on FDA's shortage list. Section 503B(a)(10) sets labeling: the label must say "This is a compounded drug" and carry the facility's name, address and phone number, the lot number and the expiration date.

Congress wrote section 503B after the 2012 fungal meningitis outbreak traced to the New England Compounding Center, to create a federal tier for compounders that make sterile drugs in volume and ship them across state lines.

What is the difference between 503A and 503B?

A 503A pharmacy is a state-licensed pharmacy that compounds for an identified patient on a prescription and answers first to its state board of pharmacy. A 503B outsourcing facility answers to FDA, meets CGMP, and may make batches for office stock.

FDA can cite either tier for insanitary conditions under section 501(a)(2)(A). The CGMP row decides what a Form 483 looks like. At a 503A pharmacy the investigator writes observations under 501(a)(2)(A); at a 503B facility the investigator cites numbered 21 CFR 211 sections. Our analysis of FDA compounding warning letters in 2026 covers the GLP-1 copies rule and the September 2026 letters that turned on it.

How does FDA register, monitor and inspect a 503B outsourcing facility?

FDA oversees a 503B outsourcing facility through five steps written into section 503B: four duties on the facility, then a risk-based inspection by FDA.

1. Election, registration and fee. The facility registers its name, place of business and unique facility identifier, and says whether it intends to compound drugs on the shortage list. It renews every year between October 1 and December 31, under 503B(b)(1). Section 744K of the FD&C Act adds an annual establishment fee: for fiscal year 2027, $22,074, or $7,142 for a qualifying small business, with a $21,427 fee for each reinspection (Federal Register notice 2026-15342, July 30, 2026). A facility that has not registered and paid by December 31, 2026 loses outsourcing facility status on January 1, 2027.
2. CGMP. Every batch is made under 21 CFR parts 210 and 211, with a licensed pharmacist supervising, under 503B(a)(1).
3. Product reports. In June and in December the facility reports each drug compounded in the prior six months: active ingredient and its source, strength, dosage form, route, package, unit count and NDC numbers, under 503B(b)(2).
4. Adverse event reports. The facility files them under 21 CFR 310.305, as section 503B(b)(5) requires.
5. Inspection. FDA schedules inspections on risk. The statute names the facility's compliance history, recall history, the inherent risk of what it compounds, its inspection history over the last four years, and whether it registered to compound shortage drugs.

Investigators record objectionable conditions on a Form 483 at the close of the inspection; our explainer on what an FDA Form 483 is covers the response window. FDA's registered list then records the agency's action after each facility's last inspection, from "Open" to a response letter, a regulatory meeting, an untitled letter or a warning letter.

Across the 18 facilities below, the median gap between two Form 483s at the same facility is 2.0 years, measured over 56 consecutive pairs in the Atlas record.

What do FDA investigators cite at 503B outsourcing facilities?

FDA investigators cite sterile process control at 503B outsourcing facilities more than anything else. We took 18 facilities from FDA's registered outsourcing facility list (current as of October 29, 2026) and pulled every Form 483 with observation detail from the FDA Form 483 database in Atlas (release of August 15, 2026). That gave 74 forms and 457 observations, a median of 6 observations per form, issued from March 2013 to May 2026.

At the subsection level, 211.113(b) appears on 55 forms. Environmental monitoring in aseptic areas, 211.42(c)(10)(iv), appears on 32 and cleaning and disinfection, 211.42(c)(10)(v), on 20. Four forms cite the product reporting rule in 503B(b)(2)(A).

Citations repeat at the same facility: 14 of the 18 received a 211.113 citation on two or more forms, and 12 received 211.192 on two or more. On each facility's latest form in Atlas, 211.113 and 211.192 each appear 14 times out of 18. The share of forms citing 211.113 moved from 74% for 2013 to 2019 to 77% for 2020 to 2026.

The per-facility counts are below; the last column comes from FDA's registered list.

Three of the 18 reached a warning letter after their last inspection. At Pine, the 2021, 2023 and 2024 forms each cite 211.113(b) and 211.192, and our tracker of FDA warning letters in October 2026 shows the August 2026 letter citing both again. SCA's Little Rock letter carried the four sections from its October 2025 form. RC Outsourcing has cited 211.113(b) and 211.192 on all five of its forms, the latest an eight-observation form on August 28, 2025.

For some facilities FDA lists a last inspection newer than the latest form in Atlas: Nephron in August 2025, Pine in November 2025, and both STAQ facilities, RC Outsourcing and Olympia in August or September 2026. Two limits apply. We picked the facilities by name from FDA's list, and a Form 483 is not a final agency finding.

If you buy from a 503B facility, look up the investigator who wrote its last Form 483 next: Atlas shows which sections that investigator has cited at other sites.

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Is Leiters Health a 503B outsourcing facility?

Leiters Health is a 503B outsourcing facility. FDA's registered list names Denver Solutions, LLC, dba Leiters Health at two locations: Englewood, Colorado, registered since March 24, 2017, and Buena, New Jersey, registered since July 1, 2022. As of October 29, 2026, the list shows the Buena facility as not yet inspected.

The Atlas record for Leiters Health in Englewood holds five FDA inspections, from February 2018 to December 2025. Each ended with a Form 483, for 26 observations in total.

• February 23, 2018: four observations, including 211.192 and the aseptic area rules 211.42(c)(10)(iv) and (v).
• July 18, 2019: one observation, 211.42(c)(10)(i), on aseptic area surfaces.
• October 7, 2021: seven observations, including 211.113(b), 211.160(b) and 211.192.
• April 5, 2024: seven observations, including 211.113(b), 211.192, 211.22(d), and both 503B(a)(10)(A) and (B) for label and container content.
• December 11, 2025: seven observations, including 211.113(b), 211.42(c)(10)(iv) and (v), 211.100(a) and 211.110(a).

211.113(b) appears on the last three forms, and the environmental monitoring subsection 211.42(c)(10)(iv) on three of the five. Investigator Margaret M Annes wrote the December 2025 form; she was also on the May 2023 inspection team at SCA's Little Rock facility. FDA's registered list records an untitled letter to the Englewood facility on June 8, 2026, after the December 2025 inspection. Our guide to the FDA untitled letter explains where that sits below a warning letter.

What are the top 503B pharmacies?

FDA does not rank 503B pharmacies, so any "top 503B" list reflects the publisher's own criteria, such as product range or service for clinics. A neutral comparison starts from FDA's registered outsourcing facility list (100 facilities as of October 29, 2026) and then reads each facility's inspection record.

On that measure, the longest records among the 18 facilities in Atlas belong to Nephron Sterile Compounding Center in West Columbia, SC (8 Form 483s, 44 observations), then Olympia Pharmaceuticals in Orlando and Central Admixture Pharmacy Services in Allentown (6 forms each). A long record means more inspections to read, and you should weigh it against what each form cites. Two facilities, Farmakeio Outsourcing and STAQ Pharma of Ohio, have no 211.113 citation on their forms in Atlas.

How can you tell if a 503B compounding pharmacy is legitimate?

A legitimate 503B compounding pharmacy appears on FDA's registered outsourcing facility list, renews its registration each year, and has an inspection record you can read. A hospital or clinic pharmacy buyer can work through five checks, in order:

1. Find the facility on FDA's registered outsourcing facility list and note its last inspection date, whether FDA issued a Form 483, and FDA's action.
2. Pull the last two Form 483s. A section cited on both, such as 211.113(b) or 211.192, is the pattern that preceded the three warning letters above.
3. Read the facility's response to the most recent form and ask for evidence of closure: revised media fill records, smoke studies, investigation reports.
4. Check labels against 503B(a)(10). Twelve of the 74 forms cite it.
5. Confirm the products you buy appear in the facility's June and December product reports.

For a 503A pharmacy, the equivalent first check is its license with the state board of pharmacy in the state where it operates.

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