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503A or 503B: Which Kind of Pharmacy Filled Your Vial

Two legal categories hide behind one word on an invoice. What the FDA says separates them, which costs more to run, and why only one is publicly checkable.

By Marla Whitfield, Pricing Editor

"Compounded" is one word covering two entirely different businesses. They are regulated differently, inspected by different people, carry different manufacturing obligations, and therefore cost different amounts to run. That difference shows up in your price, and the FDA publishes enough to let you tell which one you are buying from.

The two categories, in the FDA's own words

Section 503A covers "compounding by a licensed pharmacist in a state-licensed pharmacy, or federal facility, or by a physician." Section 503B covers "compounding by or under the direct supervision of a licensed pharmacist in an outsourcing facility."1

Outsourcing facilities are the newer category: "a category of compounders established in 2013 by the Drug Quality and Security Act," which "are inspected by FDA according to a risk-based schedule and are subject to increased quality standards."1

The one sentence that explains the cost gap

This is the whole economic difference, and the FDA states it directly:

"Drugs compounded in outsourcing facilities are subject to current good manufacturing practice (CGMP) requirements. By contrast, drugs compounded by a licensed pharmacist in a state-licensed pharmacy or federal facility, or by a physician, in accordance with the conditions of section 503A of the FD&C Act, are not."1

CGMP is a standing cost: validated processes, documented batch records, environmental monitoring, stability programmes, and the staff to run all of it. A 503B facility carries that overhead on every unit it ships. A 503A pharmacy, by law, does not.

If two sellers quote you the same compounded product at meaningfully different prices, the compounding category is one of the first places to look for the reason — and it is a reason, not an excuse on either side.

Who inspects whom

The oversight split follows the same line.

For 503A: "Generally, state boards of pharmacy have primary responsibility for the day-to-day oversight of state-licensed pharmacies that are not registered with FDA as outsourcing facilities. FDA does conduct surveillance and for-cause inspections of state-licensed pharmacies that are not registered as outsourcing facilities."1

For 503B: facilities registered under section 503B "are primarily overseen by FDA and inspected by FDA according to a risk-based schedule."1

One is routine and federal. The other is state-led, with federal attention arriving on cause. Neither is nothing; they are not the same thing.

Neither is FDA-approved, and that is not a technicality

Both categories produce drugs that have not been through approval. The FDA's language is flat: "Compounded drugs are not FDA-approved. This means that FDA does not verify the safety, effectiveness or quality of compounded drugs before they are marketed."1

CGMP compliance is a manufacturing standard, not an approval. A 503B product is made under stricter process controls than a 503A one; it has still not been reviewed for safety and effectiveness the way an approved drug has. The category difference is real and it is narrower than marketing copy usually implies.

The agency also notes that whatever the setting, "other federal law applies, including provisions regarding insanitary conditions."1

Bulk substances: the constraint that decides whether 503B can make it at all

Outsourcing facilities generally cannot compound from a bulk drug substance unless that substance appears on the 503B bulks list, or the compounded drug is on the FDA's drug shortage list at the time of compounding, distribution and dispensing. As of the FDA's April 2026 statement, "tirzepatide and semaglutide do not currently appear on the 503B bulks list or on FDA's drug shortage list."2

On 30 April 2026 the agency proposed to exclude semaglutide, tirzepatide and liraglutide from that list permanently, saying it "did not identify a clinical need for outsourcing facilities to compound these drugs from bulk drug substances," and inviting comment through 29 June 2026 before a final determination.3 As of August 2026 no final determination has been published.

The 503A side has its own constraint, described in how compounded GLP-1 pricing actually works: the essentially-a-copy restriction, and the four-prescriptions-a-month enforcement threshold the FDA published in April 2026.2

The part you can check yourself

This is where the two categories genuinely differ for a buyer, and it takes about a minute.

The FDA publishes the complete list of registered outsourcing facilities, updated weekly — the version fetched for this article was "Updated as of 8/4/2026."4 Each row carries the facility's name and city, its initial and most recent registration dates, the date of its last inspection, whether a Form 483 was issued, whether a recall was conducted, and the action taken based on that inspection. Some rows read "Not yet inspected." Some read "Warning Letter Issued" with a date.4

Registration is not permanent, either. A facility must re-register annually between 1 October and 31 December and pay an annual establishment fee; if it does not, "the facility will be removed from the list of registered outsourcing facilities on January 1 of the next calendar year."4

There is no equivalent single federal list for 503A pharmacies. Their licensing and disciplinary records sit with the state board of pharmacy in the state where the pharmacy is located — checkable, but state by state, and the FDA's own table notes that it "does not include State Board of Pharmacy actions."4

Three questions to ask a seller

Which pharmacy compounds this, by name and city?

Is it registered with the FDA as a 503B outsourcing facility, or licensed by a state board as a 503A pharmacy?

If 503B — what does the FDA's registered outsourcing facilities table say about its last inspection?

A seller that answers all three has given you something to verify. A seller that will not name the pharmacy has answered a different question, and that answer is also useful.

Related reading: our compounded semaglutide and compounded tirzepatide price boards, and the FDA warning letter archive for what the agency has said publicly about sellers in this category.

Frequently asked questions

What is the difference between a 503A pharmacy and a 503B outsourcing facility?

503A covers compounding by a licensed pharmacist in a state-licensed pharmacy, or by a physician, for an individual patient. 503B covers outsourcing facilities, a category created in 2013 by the Drug Quality and Security Act, which register with the FDA and are inspected on a risk-based schedule. The decisive difference for cost is that drugs compounded in outsourcing facilities are subject to current good manufacturing practice requirements and drugs compounded under 503A are not.

Is a 503B product FDA-approved?

No. The FDA's language is unqualified: compounded drugs are not FDA-approved, and the agency does not verify their safety, effectiveness or quality before they are marketed. CGMP compliance is a manufacturing standard, not an approval. A 503B product is made under stricter process control than a 503A one and is still not an approved drug.

Can I look up the pharmacy that made my compounded GLP-1?

If it is a 503B outsourcing facility, yes. The FDA publishes the full registered list weekly, with each facility's registration dates, last inspection date, whether a Form 483 was issued, whether a recall was conducted, and any action taken. If it is a 503A pharmacy there is no equivalent federal list — records sit with the state board of pharmacy, and the FDA's table explicitly does not include state board actions.

Why does the compounding category affect the price?

Because CGMP is a standing cost. Validated processes, batch records, environmental monitoring and stability programmes are carried on every unit a 503B facility ships, and a 503A pharmacy is not subject to those requirements. Outsourcing facilities also pay an annual establishment fee and must re-register each year between 1 October and 31 December or be removed from the list on 1 January.

References

  1. US Food and Drug Administration (2026). Compounding and the FDA: Questions and Answers. FDA.gov. https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers
  2. US Food and Drug Administration (2026). FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize (statement dated 1 April 2026). FDA Drug Alerts and Statements. https://www.fda.gov/drugs/drug-alerts-and-statements/fda-clarifies-policies-compounders-national-glp-1-supply-begins-stabilize
  3. US Food and Drug Administration (2026). FDA Proposes to Exclude Semaglutide, Tirzepatide, and Liraglutide on 503B Bulks List (30 April 2026). FDA Press Announcements. https://www.fda.gov/news-events/press-announcements/fda-proposes-exclude-semaglutide-tirzepatide-and-liraglutide-503b-bulks-list
  4. US Food and Drug Administration (2026). Facilities Registered as Human Drug Compounding Outsourcing Facilities Under Section 503B (updated 4 August 2026). FDA.gov. https://www.fda.gov/drugs/human-drug-compounding/registered-outsourcing-facilities

Medical disclaimer: This content is for general educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a licensed healthcare professional before starting, stopping, or changing any treatment.

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