The 503A Bulk Drug Substances List and Its Categories, as of 7 November 2026

By Benn Bluestein-Veyra, M.Sc. Organic Chemistry · Updated 7 November 2026

The 503A bulk drug substances list, as codified at 21 CFR 216.23, contains six substances as of 7 November 2026: Brilliant Blue G, cantharidin, diphenylcyclopropenone, N-acetyl-D-glucosamine, squaric acid dibutyl ester and thymol iodide, the last five for topical use only.^[1] Every other substance a practice asks about, including the peptides discussed at the Pharmacy Compounding Advisory Committee in July 2026, sits in one of three interim categories that describe FDA’s enforcement intent while rulemaking proceeds, or in the draft enforcement discretion policy the Department of Health and Human Services published on 30 October 2026.^[2][3]

The list matters because of the statute’s three-part test. A 503A compounder may use a bulk drug substance only if it complies with a USP or NF monograph, or is a component of an FDA-approved drug, or "appear[s] on a list developed by the Secretary through regulations", and in each case the substance must be made by an establishment registered with FDA under section 510 and accompanied by a valid certificate of analysis.^[2] A substance that fails all three branches cannot be compounded under section 503A.

A substance reaches the list through nomination, committee review and rulemaking

FDA solicited nominations for the 503A bulks list in 2015 and evaluates them in consultation with the Pharmacy Compounding Advisory Committee and the United States Pharmacopeial Convention, as section 503A requires.^[2] The final rule of February 2019 placed six substances on the list, declined four others and codified the four criteria FDA applies: the physical and chemical characterization of the substance, any safety issues raised by its use in compounded drug products, the available evidence of effectiveness or lack of effectiveness, and historical use in compounding, including references in peer-reviewed literature.^[1][2] A proposed rule of 5 September 2019 would add five more substances and decline 26 and remains unfinalized; FDA addresses further nominations through notice-and-comment rulemaking on a rolling basis.^[2][4]

The regulation also carries a warning aimed at marketing. Section 216.23(d) states that "there are inadequate data to demonstrate the safety or efficacy of any drug product compounded using any of the drug substances listed" and that anyone who represents a compounded drug made from a listed substance as FDA approved or FDA endorsed "will cause the drug to be misbranded".^[1]

The interim policy sorts nominated substances into three categories

FDA issued an interim policy in January 2017 describing the conditions under which it does not intend to take action against pharmacies, federal facilities and physicians compounding with nominated substances that have no monograph and are not components of approved drugs.^[2][5] The guidance was reissued in final form on 7 January 2025, replacing the 2017 version, and the same final guidance states that substances nominated on or after 7 January 2025 will no longer be placed into categories at all.^[2][5] The categories, as FDA describes them, are as follows.^[2]

FDA publishes the category 1 and category 3 lists in a single PDF and the category 2 list on a separate page that also states the safety risk identified for each substance.^[6][7] The PDF updated 14 May 2026 lists 49 substances in category 1, among them glutathione, methylcobalamin, nicotinamide adenine dinucleotide, melatonin, pregnenolone and "GHK-Cu (except for injectable routes of administration)", and six in category 2: cesium chloride, domperidone, germanium sesquioxide, ibutamoren mesylate, kisspeptin-10 and quinacrine hydrochloride for intrauterine administration.^[6] Category 3 runs to roughly three hundred entries.^[6] The category 2 page states the risk FDA identified for each listed substance; for ibutamoren mesylate, for example, it cites a randomized placebo-controlled trial that "was terminated early due to a potential safety signal of congestive heart failure".^[7]

A category 1 listing is the strongest interim position a substance can hold, and it still differs from the list itself. FDA’s page states that category 1 substances "may continue to be within the scope of the interim enforcement policy" until the agency decides on inclusion or removes them, for example on safety grounds.^[2] The compounding literature makes the same point from the quality side: a substance’s legal status and the quality of the preparation are separate questions, the second answered by the certificate of analysis and the pharmacy’s testing.^[8]

The withdrawn-nominations table records where most peptides went in 2026

The category 2 page, in its 22 April 2026 version, carries a second table headed "Bulk drug substances nominated but withdrawn", described as substances "previously in category 2 of the interim policies" whose nominations "were withdrawn by the nominators".^[7] As of 7 November 2026 that table names AOD-9604, BPC-157, cathelicidin LL-37, CJC-1295, dihexa acetate, emideltide (DSIP), epitalon, GHK-Cu for injectable routes of administration, ipamorelin acetate, KPV, pegylated mechano growth factor, melanotan II, MOTS-c, selank acetate, semax, thymosin alpha-1 and the thymosin beta-4 fragment known as TB-500.^[7] Ipamorelin acetate appears in both tables because it remains in category 2 under the separate 503B interim policy.^[7]

The page keeps FDA’s safety statement for each withdrawn substance. For BPC-157 it reads that compounded drugs containing it "may pose risk for immunogenicity for certain routes of administration and may have complexities with regard to peptide-related impurities and active pharmaceutical ingredient (API) characterization", and that the agency "lacks sufficient information to know whether the drug would cause harm when administered to humans".^[7] For the thymosin beta-4 fragment the page states that FDA "has not identified any human exposure data" for the drug products.^[7]

GHK-Cu followed its own path. The category PDF records that "GHK-Cu (except for injectable routes of administration)" was removed from category 1 on 22 April 2026 because its nominations were withdrawn, that on 5 May 2026 one nominator clarified it had meant to withdraw only the injectable route, and that the non-injectable entry was added back on 14 May 2026, with FDA stating it intends to consult the PCAC before the end of February 2027.^[6] The injectable form stays in the withdrawn table.^[7]

The PCAC heard seven peptides on 23 and 24 July 2026

FDA announced the meeting in the Federal Register on 16 April 2026 under docket FDA-2025-N-6895.^[9] On 23 July 2026 the committee discussed BPC-157, KPV, TB-500 and MOTS-c (each as free base and acetate), and on 24 July 2026 emideltide, semax and epitalon, all "being considered for inclusion on the 503A Bulks List".^[9][10] The notice records the use FDA evaluated for each: ulcerative colitis for BPC-157; wound healing and inflammatory conditions for KPV; wound healing for TB-500; obesity and osteoporosis for MOTS-c; opioid withdrawal, chronic insomnia and narcolepsy for emideltide; cerebral ischemia, migraine and trigeminal neuralgia for semax; and insomnia for epitalon.^[9] The meeting page states that advisory committees "make non-binding recommendations to the FDA, which generally follows the recommendations but is not legally bound to do so".^[10]

As read on 7 November 2026, the meeting page (content current as of 6 August 2026) carries the agenda, the uses evaluated and the webcast links, and posts no vote summary or minutes.^[10] A committee discussion changes nothing in 21 CFR 216.23 by itself; the statute requires FDA to consult the committee before issuing a regulation, and the list changes only when a final rule is published.^[1][2]

The 30 October 2026 HHS draft policy covers six peptides and is not the list

On 30 October 2026 the Secretary of Health and Human Services published a notice of availability of an "Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances" at 91 FR 68526, docket HHS-OASH-2026-0496.^[3] The notice describes a policy on the use of certain peptide bulk drug substances under section 503A "while the list of bulk drug substances that can be used in compounding under section 503A of the FD&C Act (the 503A bulks list) is developed through rulemaking", states that HHS "does not intend to take enforcement action against a State-licensed pharmacy, Federal facility, or licensed physician compounding a drug product using a peptide bulk drug substance found in Appendix A", and adds that FDA’s future rulemakings "may propose adding some or all of these peptides to the 503A bulks list".^[3] The notice also states that the draft "does not establish any rights for any person and is not binding on HHS or the public", and it accepts written comments for two weeks from 30 October 2026, which is 13 November 2026.^[3] Appendix A of the policy document names the six peptides the committee heard in July, BPC-157, epitalon, KPV, MOTS-c, semax and TB-500, as the explainer linked below records from the hhs.gov text.

The policy is a statement of enforcement discretion. The six peptides remain in the withdrawn table on FDA’s category 2 page, remain absent from 21 CFR 216.23, and would reach the list only through the rulemaking the notice itself anticipates.^[1][3][7] The explainer linked below sets out the policy’s ten conditions and route limits.

21 CFR 216.24 is the list of what may never be compounded

Section 503A(b)(1)(C) bars compounding of any drug on FDA’s list of products "withdrawn or removed from the market because such drug products or components of such drug products have been found to be unsafe or not effective", and section 503B(a)(4) applies the same bar to outsourcing facilities.^[2] The list is codified at 21 CFR 216.24 and, as read on 7 November 2026, carries 84 entries from adenosine phosphate to zomepirac sodium, several qualified by dosage form or route.^[11] The regulation states that these products "may not be compounded under the exemptions provided by section 503A(a) or section 503B(a)".^[11]

A separate provision of section 503A excludes drugs that FDA identifies by regulation as presenting "demonstrable difficulties for compounding"; as of 7 November 2026 part 216 contains only sections 216.23 and 216.24, so no such list has been codified and the withdrawn list at 216.24 is the operative exclusion a practice will meet.^[11] The outbreak record points the same way: contamination of sterile preparations, rather than ingredient identity, drove most of the harm the Centers for Disease Control and Prevention reviewed for 2001 to 2013, and the Tennessee investigation of the 2012 outbreak described 66 case patients.^[12][13]

How a practice reads the lists for a given substance

The order of questions follows the statute. The first is whether the substance has a USP or NF monograph; a monograph substance needs no list.^[2] The second is whether it is a component of an FDA-approved drug.^[2] Only a substance that fails both questions depends on 21 CFR 216.23, and for that substance the practice reads, in order: the codified list; the category 1 and 3 PDF and its "updated" date; the category 2 page, including the withdrawn table and the stated safety risk; and any current enforcement policy, with its conditions.^[1][6][7] A 2021 pharmacy-practice article describes the same stepwise approach and notes that no single document holds the whole answer.^[14]

Whatever branch applies, the remaining 503A conditions are unchanged: the bulk substance must come from an establishment registered under section 510 with a valid certificate of analysis, the preparation may not be a regular or inordinate copy of a commercially available product, and the drug may not appear on 216.24.^[2][11] A review of 113 FDA compounding warning letters from 2017 to 2021 found that 72 of the 112 to 503A facilities cited products made without valid patient-specific prescriptions and 28 named drugs outside the 503A exemption.^[15] The 2020 National Academies report on compounded hormone preparations reviewed whether the available evidence supports the claims made for them and which patients might need them in place of an approved product.^[16]

• Monograph or approved-drug component: compoundable under 503A without reference to the bulks list, subject to the other conditions.^[2]
• Codified at 21 CFR 216.23: compoundable under 503A, for the listed route only, with the misbranding caution in 216.23(d).^[1]
• Category 1: FDA does not intend to take action while it evaluates, provided the guidance conditions are met.^[2][6]
• Category 2, category 3, or a withdrawn nomination: outside the interim policy; FDA would consider action under its general enforcement policies.^[2][7]
• Named in the HHS draft policy: a proposed statement of enforcement discretion with stated conditions, open for comment to 13 November 2026, and still outside 216.23.^[3]
• On 21 CFR 216.24: may not be compounded under 503A or 503B.^[11]

ExaVeyra supplies compounded preparations through a licensed 503A pharmacy partner on patient-specific prescriptions, and the pharmacy applies this reading to each substance before it compounds; a certificate of analysis is available for each lot. The categories and the draft policy change on their own schedules; the dates above are the dates each document was read.

This article summarizes publicly available federal regulation for licensed practitioner education. It is not legal advice, medical advice, or regulatory guidance, and it does not establish that any particular product or practice is compliant. Confirm current federal and state obligations with qualified counsel.