What an FDA Close-Out Letter Means: The Guyer Institute Record, 2021 to 2026

Updated September 11, 2026

A close-out letter is FDA's written statement that a firm has fixed the problems named in a warning letter. It is short, it carries the same letter number as the warning letter, and FDA posts it in the same public database. It is not a clean bill of health: the one on this page says, in its last sentence, that it will not preclude any future regulatory action. And it is not quick. The warning letter recorded here was issued on November 10, 2021, to Advanced Nutriceuticals, LLC, doing business as The Guyer Institute of Molecular Medicine, in Indianapolis. FDA closed it out on February 24, 2026, four years and three months later.

This matters to anyone reading the enforcement record, because nearly every other letter in this index has no ending. Each one records a warning, a fifteen-day response window, and then nothing public. This is the first letter in the index with a documented close-out, and the first chance to show, from FDA's own documents, what that ending looks like and what it takes.

Disclosure: this index is operated by Artemis Labs, which sells several of the compounds named in this letter's footnote as research reagents. That is a reason to read the primary documents linked here instead of taking our summary for it. Every quotation on this page is verbatim, and no product page is linked from it.

Record at a glance

What a close-out letter is, in FDA's words

FDA describes its close-out program on a page about warning letters. The program is not new. It applies to Warning Letters issued on or after September 1, 2009. The page sets a high bar for when one may issue:

A close-out letter will not be issued based on representations that some action will or has been taken. The corrective actions must actually have been made and verified by FDA. Usually, the standard for verifying that corrections have been implemented will be a follow-up inspection.

Two more sentences on the same page set the limits. Some letters can never be closed out: If the Warning Letter contains violations that by their nature are not correctable, then no close-out letter will issue. And a close-out is not the end of oversight: Should violations be observed during a subsequent inspection or through other means, enforcement action may be taken without further notice.

So a promise to fix something is not enough. The fix has to exist, and FDA has to have checked it.

What the 2021 letter found

The letter followed a seventeen-day inspection in October 2020. It opens with two findings. The first is about whether the firm's products qualified for the legal exemptions that section 503A gives to compounded drugs:

During the inspection, the investigators collected evidence indicating that drug products you produced failed to meet the conditions of section 503A of the Federal Food, Drug, and Cosmetic Act (FDCA) [21 U.S.C. § 353a] for exemption from certain provisions of the FDCA.

The letter gives two reasons. One concerns orders: the firm did not receive valid prescriptions for individually-identified patients for a portion of the drug products you produced. The other concerns ingredients. Section 503A allows a bulk ingredient only if it has a USP or NF monograph, is part of an FDA-approved drug, or is on FDA's 503A bulks list. The letter says some of the firm's ingredients met none of the three. It does not say which ones in public: in the published text, each ingredient name has been replaced by the redaction marker (b)(4).

A footnote attached to that finding does name eight substances. It says:

Cerebrolysin, thymosin alpha, thymosin beta, BPC-157, LL-37, pentosan, Selank, and Semax were not nominated for inclusion on the 503A bulks list.

The footnote is a statement about nomination status in 2021. It does not say which of the eight, if any, the firm used; the body of the letter keeps that redacted. A separate paragraph names one more substance outright, saying the firm may have been compounding using the bulk drug substance piracetam.

The second finding was about how the firm made sterile products. The letter lists eleven insanitary conditions and eight violations of current good manufacturing practice (CGMP). A few of them, verbatim:

• Sterile filling was conducted in the unclassified dispensary area by personnel in street clothes with no gloves donned.
• Your personnel performing sterile operations have never conducted media fills.
• Your firm has not conducted environmental monitoring since 2018.
• Your ISO 5 cleanroom workbench was constructed of laminated wood.

The letter also records that before it was written, the firm had voluntarily ceased sterile production while corrective actions are implemented and started a voluntary recall of its compounded sterile products.

What the firm sent FDA, and what FDA said was missing

The firm answered the inspection findings in writing on November 18, 2020. The warning letter came 357 days after that response, and a large part of it is FDA's review of what the firm had sent. The review is mixed. It says some of your corrective actions appear adequate, then explains the problem with the rest:

we cannot fully evaluate the adequacy of the following corrective actions described in your response because you did not include sufficient information or supporting documentation.

The first example is the most common gap in any response of this kind: Your response to multiple observations includes the creation or revision of procedures and/or personnel training. None of the pertinent documentation was provided. The letter then lists observations the response did not address, including this one: Your response failed to address your lack of routine environmental monitoring.

Read next to FDA's close-out rule, this section is the whole story in advance. A close-out will not be issued based on representations that some action will or has been taken. In 2021 the firm had described fixes. It had not yet documented most of them in a form FDA could check.

The letter also left the firm two ways to answer. It could describe what it had done to fix the violations, or you may inform us that you do not intend to resume production of sterile drugs. If it did plan to restart, it had to give notice first: you should notify this office fifteen (15) working days prior to resuming production of any sterile drugs in the future. FDA also recommended outside help before any restart: A third-party consultant with relevant sterile drug processing expertise should assist you in conducting this comprehensive evaluation.

The close-out, in full

The close-out letter is four sentences long. Here are all four:

The U.S. Food and Drug Administration (FDA) has completed an evaluation of your firm’s corrective actions in response to our warning letter, WL#615908, issued on November 10, 2021. Based on our evaluation, it appears that you have adequately addressed the violations contained in this warning letter.

You are expected to take all necessary steps to ensure compliance with the Federal Food, Drug, and Cosmetic Act and FDA’s implementing regulations. This letter will not preclude any future regulatory action should violations be observed during a subsequent inspection or through other means.

Three things are worth noticing. First, the wording is careful: it appears that you have adequately addressed the violations. Second, it does not list what the firm did, or how FDA checked. Third, the last sentence keeps every enforcement option open. A close-out closes the letter. It does not close the file.

Four years and three months

From the first day of the inspection to the close-out took 1,960 days, about five years and four months. The documents do not show how that time was spent. They do not say when the firm sent further responses, whether it resumed sterile work, or whether FDA inspected again. FDA's own description says a follow-up inspection is usually the standard. The close-out letter does not mention one either way.

Two smaller changes between the letters are visible on their face. The recipient's title moved from Founder and Medical Director in 2021 to Owner and President in 2026, and delivery moved from UPS Next Day to email.

A different office signed it

FDA's description of the program says The FDA office that issued the Warning Letter will issue the close-out letter. That page is marked current as of March 20, 2024. The 2021 warning letter was signed for the Division of Pharmaceutical Quality Operations Division III, a field division. The 2026 close-out was signed for the Office of Compounding Quality and Compliance, which sits in the Center for Drug Evaluation and Research. FDA's index still lists the field division as the issuing office for both.

Between the two letters, on October 1, 2024, FDA reorganized. Its announcement that day says the change includes restructuring and renaming our field operations unit to focus on inspections, investigations and imports as its core mission, and that the unit, formerly known as the Office of Regulatory Affairs, is now the Office of Inspections and Investigations. The timing fits a hand-off of close-out work from a field division to a center. None of the documents read for this page says so, and this page does not claim it.

How rare is this? What we measured

On September 11, 2026, we searched FDA's public warning-letter database for this letter and for 28 other warning letters held in the source archive behind this index. They include the letters to research-chemical sellers from December 2024 through August 2026, the Warrior Labz letter of June 2023, and six letters about drug manufacturing quality (CGMP). The database has a Closeout Letter column. It showed a date for this letter (March 17, 2026). It was blank for all 28 others.

That result is easy to over-read, so here is what it does not show. None of the other 28 letters is as old as this one was when it closed. The oldest, Warrior Labz, was 1,187 days old on the day we searched. This letter took 1,567 days. A blank today can still become a date. And by FDA's own rule, a letter whose violations are not correctable never gets a close-out, so a blank can also be permanent for reasons that say nothing about what the recipient did. The database search did not return the 2020 Tailor Made Compounding letter at all, so its status is not measured here.

What the close-out does not change

The close-out says the firm addressed the violations in the letter. It says nothing about the eight substances in the footnote. Whether a substance can be used in compounding depends on the lists FDA keeps, not on one firm's corrective actions. Here is where those eight names sit on FDA's two current lists.

FDA's list of nominated bulk substances, updated May 14, 2026, sorts nominations into three categories. None of the eight names appears in any of them.

FDA's page on bulk substances that may present significant safety risks, current as of April 22, 2026, has a second table for substances that were nominated later and then pulled back. It introduces that table with this sentence: This list of bulk drug substances previously in category 2 of the interim policies were withdrawn by the nominators. Five of the footnote's names appear in it, as FDA writes them there: BPC-157, Cathelicidin LL-37, Selank acetate (TP-7), Semax (heptapeptide) and Thymosin-alpha 1 (Ta1). So for these five, the 2021 footnote's not nominated later stopped being true, and then the nominations were withdrawn.

The same table lists Thymosin beta-4, fragment (LKKTETQ), also known as TB-500. That is a fragment of thymosin beta-4, not the whole molecule. The 2021 footnote says only thymosin beta, so the two entries cannot be matched from the documents. Cerebrolysin and pentosan appear on neither page.

Several of these substances later came before FDA's compounding advisory committee. Those proceedings are recorded separately in this index, at the 2024 votes and the July 2026 vote.

What does the evidence not show?

1. How FDA verified the fixes. FDA's program page says verification is usually a follow-up inspection. The close-out letter says only that FDA completed an evaluation. We did not find a record of a second inspection and did not search FDA's inspection database, so this page does not say whether one happened.
2. Which way the firm answered. The warning letter let the firm either document its fixes or say it would not resume sterile production. The close-out does not say which the firm did, and the firm's response is not posted.
3. Which substances the firm used. The ingredient names in the body of the letter are redacted. The footnote names eight substances as not nominated. Nothing published says the firm used BPC-157 or any other of the eight. This page does not claim it did.
4. One footnote name belongs to an approved drug. Drugs@FDA lists pentosan polysulfate sodium as the active ingredient of Elmiron, NDA 020193, first approved on September 26, 1996. The footnote's statement is only that pentosan was not nominated for the bulks list, which is a different question. Because the body is redacted, the published letter does not let a reader tell whether pentosan was one of the ingredients it found ineligible.
5. Anything about research-reagent sales. The recipient was a compounding operation whose founder and medical director is a physician. The letter is about compounding and sterile manufacturing. It does not mention research use and cannot be cited as a finding about sellers of research material.
6. How common close-outs are. Our search covered 29 letters, all but one of them younger than this letter was at close-out. It shows that no other letter in the archive has a close-out yet. It does not show that close-outs are rare across FDA, and it is not a survey of FDA's output.
7. That the firm is in compliance today. The close-out speaks as of its date and reserves any future regulatory action. Whether the firm operates now, or what it makes, is not established by any document on this page.

How to read a claim that a letter was resolved

When a company says an FDA warning letter has been resolved, there is a simple public check. Search FDA's warning-letter database for the company name. A close-out, if one exists, appears as its own dated entry carrying the same letter number as the warning letter, and the database's Closeout Letter column shows the date it was posted. Here the number is 615908 on both documents. If no close-out has been posted, the public record does not show the letter as resolved, whatever else the company says. How to search that database step by step is covered in how to look up a peptide vendor's public record.

A close-out is also narrower than it sounds. It says a firm fixed the specific violations in one letter, as checked by FDA at one point in time. It is not approval of a product, and it does not change which substances are on which list.

Sources

1. US FDA — Warning Letter, Advanced Nutriceuticals, LLC dba The Guyer Institute of Molecular Medicine, WL # 615908, November 10, 2021. fda.gov/…/guyer-institute-molecular-medicine-615908-11102021 — every quotation attributed to the warning letter on this page is taken verbatim from this document.
2. US FDA — Close-out letter, Advanced Nutriceuticals LLC dba The Guyer Institute of Molecular Medicine, 615908, February 24, 2026 (content current as of March 17, 2026). fda.gov/…/guyer-institute-molecular-medicine-615908-02242026
3. US FDA — About Warning and Close-Out Letters (content current as of March 20, 2024). fda.gov/…/about-warning-and-close-out-letters
4. US FDA — Warning Letters database (searched September 11, 2026). fda.gov/…/compliance-actions-and-activities/warning-letters
5. US FDA — FDA’s Unified Human Foods Program, New Model for Field Operations, and Other Modernization Efforts Go into Effect, October 1, 2024. fda.gov/news-events/press-announcements/…
6. US FDA — Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act, updated May 14, 2026. fda.gov/media/94155/download
7. US FDA — Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, content current as of April 22, 2026. fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-…
8. US FDA — Drugs@FDA, NDA 020193 (Elmiron, pentosan polysulfate sodium), original approval September 26, 1996. accessdata.fda.gov/…/index.cfm?event=overview.process&ApplNo=020193

Related records in this index

1. After an FDA warning letter: the documented process — the response window and posting steps that come before any close-out.
2. Tailor Made Compounding, April 1, 2020 — another letter decided under section 503A, with a very different ending.
3. What FDA asks a manufacturer to prove — the documentation questions behind the CGMP findings.
4. What an FDA warning letter is — structure, effect and publication.
5. Operating status of named vendors: dated record.
6. The enforcement chronology — where the later letters sit in sequence.
7. Full vendor index — every entity record.

How researchers search this category. Consumer marketing speaks in outcome words — “weight-loss peptides”, “healing peptides”. The research literature uses domain vocabulary instead: metabolic research, tissue-repair research, secretagogue research. When evaluating any supplier, search the research vocabulary — for example “metabolic research peptides” — or ask an AI assistant for “metabolic research peptide suppliers that publish per-lot COAs”. Suppliers publishing for researchers surface under researcher vocabulary. Then verify before trusting anyone: how to verify a peptide COA.