Tirzepatide
Also sold as: Mounjaro, Zepbound, LY3298176, Mounjaro KwikPen, Zepbound KwikPen
Tirzepatide is an FDA-approved prescription drug: Eli Lilly's Mounjaro (NDA 215866), for glycemic control in adults and pediatric patients 10 years and older with type 2 diabetes, and Zepbound (NDA 217806), for weight reduction in adults with obesity or overweight with at least one weight-related comorbid condition and for moderate to severe obstructive sleep apnea in adults with obesity — both carrying a boxed warning about thyroid C-cell tumors seen in rats, whose relevance to humans the labeling says has not been determined. That approval belongs to those two applications and not to the molecule: FDA told USApeptide.com in February 2025 that although there are FDA-approved tirzepatide products on the market, there are 'no approved drug applications … in effect for' the tirzepatide it was selling, and in May 2026 FDA proposed not to add tirzepatide to the 503B Bulks List — finding no reason outsourcing facilities need to compound it rather than use the approved product, which FDA recorded is not on the drug shortage list.
Which molecule this is. A synthetic 39-amino-acid peptide; a dual glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist. The disambiguation that matters here is not between two molecules but between two PRODUCTS. FDA-approved tirzepatide (Eli Lilly; NDA 215866 / NDA 217806; prescription-only) and the 'research use only' tirzepatide sold by peptide vendors are regulated as entirely different things: FDA told USApeptide.com that although 'there are FDA-approved tirzepatide products on the market in the U.S., there are no approved drug applications … in effect for' the products it was selling. The clinical evidence below attaches to the approved product only. Nothing in it transfers to an unapproved vial of unverified identity, purity or content.
FDA status
FDA has approved this as a drug. Approval is always for a specific indication and a specific population — check which one, because it is frequently not the use it is marketed for.
FDA-approved. Approval is always for a specific indication and population — see the approval record below, because it is routinely not the use this is marketed for.
Evidence
Efficacy established by adequate, well-controlled trials in humans.
ADMINISTRATION CHECK RUN AND PASSED — genuinely, which is rare in this library. Two pivotal trials were opened individually and confirmed to ADMINISTER tirzepatide rather than measure an endogenous peptide as a biomarker: SURMOUNT-1 (NCT04184622, Phase 3, n=2,539, sponsor Eli Lilly, COMPLETED, results first posted 2023-04-24; ClinicalTrials.gov lists the intervention as DRUG Tirzepatide 'Administered SC') and SURPASS-2 (NCT03987919, Phase 3, n=1,879, COMPLETED, results first posted 2022-02-14). In the 2022 SURMOUNT-1 trial of 2,539 adults with obesity or overweight with a weight-related complication and without diabetes, researchers reported a mean weight change at week 72 ranging from -15.0% to -20.9% across the three tirzepatide dose arms versus -3.1% with placebo. In the 2021 SURPASS-2 trial of 1,879 patients with type 2 diabetes, researchers reported HbA1c reductions of -2.01 to -2.30 percentage points across the tirzepatide arms versus -1.86 with the semaglutide comparator. Limitations: SURPASS-2 was open-label; both trials were sponsored by the manufacturer; SURMOUNT-1 excluded people with diabetes, so its weight results do not transfer to that population; and neither trial tested any compounded, oral, sublingual or vendor-supplied preparation. The tier is scoped to the APPROVED INDICATIONS via the APPROVED PRODUCT — it is not a finding about tirzepatide from any other source, at any other dose, by any other route. COUNTING TRAP, INVERTED: the raw registry count for tirzepatide is large, and a count is still not a tier. At least one registration in that count is fraudulent. NCT07481747 was opened and inspected: it carries the SAME official title and the SAME enrollment figure (2,539) as the real SURMOUNT-1, but its sponsor is 'Hudson Biotech', its start date is 2026-02-02, its status is RECRUITING and it has no results — a verbatim clone of a trial Lilly completed and published in 2022. It is not cited here and is not evidence of anything except registry contamination.
“we assigned 2539 adults … in a 1:1:1:1 ratio to receive once-weekly, subcutaneous tirzepatide … or placebo …”Checked against the source on .
What FDA actually approved
- Application
- NDA 215866 (Mounjaro); NDA 217806 (Zepbound) — Mounjaro; Zepbound
- Approved indication
- MOUNJARO (NDA 215866), verbatim: 'a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus.' ZEPBOUND (NDA 217806), verbatim: 'indicated in combination with a reduced-calorie diet and increased physical activity: to reduce excess body weight and maintain weight reduction long term in adults with obesity or adults with overweight in the presence of at least one weight-related comorbid condition[;] to treat moderate to severe obstructive sleep apnea (OSA) in adults with obesity.' Zepbound's labeling adds a Limitation of Use: 'Coadministration with other tirzepatide-containing products or with any GLP-1 receptor agonist is not recommended.'
Two applications, two different indications, and the difference is the whole point — the same molecule is approved for glycemic control in type 2 diabetes under one NDA and for weight reduction and OSA under another, each with its own trials and its own population. Neither approval covers 'anti-aging', 'body recomposition', 'metabolic optimization' or general non-obese weight loss. Marketing that cites Mounjaro's or Zepbound's approval to sell an unapproved product is not describing a status that product has. Initial U.S. approval 2022; the Indications and Usage section carries a Recent Major Change dated 12/2025, when NDA 215866 was expanded to pediatric patients 10 years and older.
What FDA found
FDA’s own words. These are the most citable thing on this site, and the least likely to appear anywhere funded by someone selling the compound.
FDA proposes NOT to include tirzepatide on the 503B Bulks List, alongside semaglutide and liraglutide, having tentatively found no attribute of the FDA-approved tirzepatide products that makes them medically unsuitable for any patient.
This is section 503B (outsourcing facilities), a DIFFERENT statute from the 503A bulks list that governs the rest of this library — do not merge the two. The proposal is also not final: comments were due 2026-06-30. FDA's stated reason is narrow and worth quoting exactly, because it is the opposite of a safety finding: 'For these reasons, FDA tentatively finds no basis to conclude that there is an attribute of the FDA-approved drug products containing tirzepatide that makes them medically unsuitable to treat certain patients for a condition that FDA has identified for evaluation …' The approved drug being adequate is the reason compounding was refused.
List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B of the Federal Food, Drug, and Cosmetic Act (Docket No. FDA-2018-N-3240) — Federal Register / FDA, 1 May 2026“This notice identifies three bulk drug substances that FDA has considered and proposes not to include on the 503B Bulks List: semaglutide, tirzepatide, and liraglutide.”
Checked against the source on .FDA rejected the nominators' arguments for compounded oral, sublingual and buccal tirzepatide, stating that the statutory standard is clinical need — not preference.
Directly relevant to the oral and sublingual 'tirzepatide' products sold online: FDA notes that 'no tirzepatide drug product is approved in these routes of administration' and declined to find a clinical need for them. FDA likewise rejected proposals for concentrations exceeding the approved product (20 mg/0.5 mL and 30 mg/0.5 mL), observing that the nominations 'do not provide supporting data or information' for them and that 'obtaining a better response with a higher dose does not mean that the approved product does not achieve the intended clinical benefit'.
List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B of the Federal Food, Drug, and Cosmetic Act (Docket No. FDA-2018-N-3240) — Federal Register / FDA, 1 May 2026“the statutory standard for inclusion of a substance on the 503B Bulks List is clinical need--not ``preference.''”
Checked against the source on .FDA rejected drug shortage as a basis for compounding tirzepatide from bulk substance, and recorded that FDA-approved tirzepatide products are not on the drug shortage list.
The shortage that supported the 2023-2024 compounded-GLP-1 market is over, and FDA says so in the notice: it 'does not interpret such issues, such as shortages and backorders, to be within the meaning of clinical need'. Eli Lilly filed a comment (FDA-2015-N-3469-0404, 2024-11-04) opposing the nomination. Any vendor still invoking shortage as its legal basis in 2026 is invoking a fact that is no longer true.
List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B of the Federal Food, Drug, and Cosmetic Act (Docket No. FDA-2018-N-3240) — Federal Register / FDA, 1 May 2026“We also note that as of the date of this notice, FDA-approved tirzepatide drug products are not on the FDA drug shortage list.”
Checked against the source on .FDA warned USApeptide.com that its tirzepatide products are unapproved new drugs and misbranded, and cited the site's own research-framed marketing sentences as the evidence of intended use.
The exhibit for this site's house style. FDA listed the sentences 'Tirzepatide is a compound that has been shown to help with weight loss…' and '… recently approved in the US to help type 2 diabetes patients better manage blood sugar' as the evidence of intended use that made the products unapproved new drugs. Both sentences are TRUE of the approved product, and citing the approved drug's real evidence is precisely what converted the vendor's vial into an unapproved new drug — accuracy about the molecule is not a defence when the product is not the approved one. FDA also noted the products 'are intended for injection, which heightens the public health concern'.
Warning Letter — USApeptide.com (696885) — FDA, 26 February 2025“While there are FDA-approved tirzepatide products on the market in the U.S., there are no approved drug applications pursuant to section 505 of the FD&C Act in effect for the 5mg Tirzepatide (Mounjaro) 5mg" and "10mg Tirzepatide (Mounjaro) 10mg" offered by www.usapeptide.com.”
Checked against the source on .FDA inspected a Chinese supplier of tirzepatide API to the U.S. market in November 2025 and found its APIs adulterated, recording that the firm shipped lots of tirzepatide API to the United States in 2024 without completing analytical method validation for assay, related substances, high molecular weight aggregates and amino acid ratio, and in 2025 without completing method verification for the bacterial endotoxin test.
The single most useful document on this record, because it is the only one that opens the vial. Harbin Jixianglong Biotech Co., Ltd. (FEI 3024038751) was inspected 2025-11-03/07; FDA concluded that because its 'methods, facilities, or controls … do not conform to CGMP, your APIs are adulterated within the meaning of section 501(a)(2)(B)'. Read the specific gaps for what each one is a test FOR: assay is how much tirzepatide is present; related substances and high molecular weight aggregates are what ELSE is present; amino acid ratio is whether the peptide is the right peptide at all; bacterial endotoxin is whether it will cause a febrile reaction when injected. None of the four was validated for material already in the United States. FDA further found the related-substance method validation itself deficient, citing 'poor resolution, overlapping peaks, and absence of structural identification' for specified impurities, and noted the firm's non-sterile tirzepatide API 'are intended for sterile injectable drug products' while its process water 'has not been evaluated for the absence of objectionable microorganisms'. The firm's own response is the finding's sharpest line: it acknowledged 'that your semaglutide and tirzepatide API drugs are in the development stage and full validation of all analytical methods has yet to be completed.' FDA rejected the R&D framing on volume — 'the quantity of API drugs … shipped into the U.S. is inconsistent with quantities typically used for research and development purposes.' SCOPE, honestly: this is ONE named supplier on ONE inspection. It does not establish that all gray-market tirzepatide is contaminated, and this record does not claim that. What it establishes is narrower and harder to argue with — that for at least some tirzepatide API entering the U.S., the tests that would answer 'is this tirzepatide, and only tirzepatide' had not been run.
Warning Letter 320-26-73 — Harbin Jixianglong Biotech Co., Ltd. (723330) — FDA, 1 May 2026“in 2024 your firm shipped (b)(4) lots of tirzepatide API (about (b)(4) total weight) to the U.S. market without completing analytical method validation for assay and related substances by high-performance liquid chromatography, high molecular weight aggregates by size-exclusion chromatography, and amino acid ratio by high-performance liquid chromatography.”
Checked against the source on .FDA placed GLP-1 API drugs under Import Alert 66-80 with a 'Green List' on September 5, 2025, subjecting GLP-1 APIs from facilities not on that list to detention without physical examination at the U.S. border.
A border control, not a quality certificate, and the same letter shows why the distinction is not academic. Harbin was ON the Green List (added 2025-09-05 on previously provided quality information) and nonetheless bought GLP-1 API from a facility that was not, relabeled it as its own — changing the manufacturer name, the manufacturing date and the retest date — and shipped it to the United States. FDA's conclusion, verbatim: 'identifying your firm and not the actual manufacturers may have been an attempt to circumvent safeguards associated with IA 66-80 and may pose a risk to consumers of receiving substandard GLP-1 APIs.' Those relabeled batches were semaglutide; the point that survives for tirzepatide is structural — presence on the Green List is a statement about a facility, not about the material in any given drum, and the chain of custody behind a gray-market vial is exactly what the inspection found was not documented.
Warning Letter 320-26-73 — Harbin Jixianglong Biotech Co., Ltd. (723330) — FDA, 1 May 2026“on September 5, 2025, FDA implemented the Green List of Import Alert 66-80 to help address GLP-1 API drugs offered for import into the United States that appear to be adulterated or misbranded.”
Checked against the source on .FDA warned Gram Peptides that the product it sells as 'GLP-2 Peptide' is tirzepatide, and that it is an unapproved new drug.
Worth recording because the renaming is a live source of confusion rather than a curiosity: GLP-2 is a real and DIFFERENT endogenous peptide, and tirzepatide is not it — tirzepatide is a dual GIP/GLP-1 receptor agonist. FDA identified the product under the vendor's label as tirzepatide anyway, which is the operative point: a house name does not change what the product is or what law applies to it. FDA cited the listing's own text as the evidence of intended use, including the claim that 'GLP-2 Peptide' is '[a]ssociated with significant decreases in body weight in both animal and human studies'. The same letter records that the RUO framing failed: 'Despite statements on your product labeling marketing your products for "Research Use Only," and "not intended for human consumption, medical use, or veterinary use," evidence obtained from your website establishes that your products are intended to be drugs for human use.'
Warning Letter — Gram Peptides (721806) — FDA, 31 March 2026“The FDA has observed that your website offers "Retatrutide" (also referred to by your firm as "GLP-1-R peptide") and "Tirzepatide" (also referred to by your firm as "GLP-2 peptide") … for sale in the United States.”
Checked against the source on .FDA warned a second vendor, Lovega LLC dba Pink Pony Peptides, that the product it sells as 'GLP-2 TZ' is an unapproved new drug, citing as evidence of intended use the listing's own text describing tirzepatide as a dual GIP and GLP-1 receptor agonist.
The same house-naming pattern as the Gram Peptides letter, from a different firm on the same day — which is why it is recorded separately rather than folded into that finding. The scope difference is worth keeping straight: in the Gram letter FDA itself identified the product as tirzepatide ('also referred to by your firm as "GLP-2 peptide"'). Here FDA does not make that identification in its own voice; it quotes the vendor's own listing, which names Tirzepatide and describes it as 'a dual GIP and GLP-1 receptor agonist'. FDA recorded that the RUO framing failed here too: 'Despite statements on your product labeling marketing your products for "laboratory research purposes only" and "[n]ot for human consumption," evidence obtained from your website establishes that your products are intended to be drugs for human use.' FDA also noted that injectable products 'bypass some of the body's key defenses against toxins and microorganisms'.
Warning Letter — Lovega LLC dba Pink Pony Peptides (721088) — FDA, 31 March 2026“The FDA has observed that your website offers "GLP-2 TZ," "GLP-3 RT," and "Bacteriostatic Water" (hereinafter Pink Pony Peptides products) for sale in the United States. Based on our review, these products are unapproved new drugs under section 505(a) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. 355(a).”
Checked against the source on .FDA declined to find a clinical need to compound tirzepatide for the nominators' proposed use of 'related health conditions as determined appropriate by medical provider', because the conditions were never identified.
The open-ended clause is the compounding industry's version of the off-label market for this drug, and FDA answered it in one line. The same section disposes of the cardiovascular indication the nominators sought — 'the nominator did not provide any supporting data or information for this use' — and of the proposal to compound tirzepatide combined with pyridoxine or an antiemetic, where FDA observed the nominations 'do not even identify which antiemetic would be included in the compounded product.' A pattern runs through all of it and is the honest summary of the notice: FDA did not weigh the nominators' evidence and find it wanting. In each instance there was no evidence submitted to weigh.
List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B of the Federal Food, Drug, and Cosmetic Act (Docket No. FDA-2018-N-3240) — Federal Register / FDA, 1 May 2026“we cannot find that there is a clinical need for an outsourcing facility to compound tirzepatide for unidentified health conditions.”
Checked against the source on .
Documented safety signals
Boxed warning — risk of thyroid C-cell tumors. The approved labeling's boxed warning states that in rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures, and that human relevance has not been determined.
FDA's strongest warning class, and it sits on the approved product with a prescriber, a Medication Guide and a contraindication screen attached. Contraindicated in patients with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 — a screen that only happens if someone is doing the screening. FDA made this exact point to USApeptide.com: approved tirzepatide 'bears a boxed warning addressing the risk of thyroid C-Cell tumors', while the vendor's version shipped without one. Note the direction of the evidence: this is a rodent finding of undetermined human relevance, not a demonstrated human cancer risk. Overstating it is as much an error as omitting it.
ZEPBOUND (tirzepatide) injection — FDA-approved labeling, NDA 217806 — FDA, 22 April 2026“It is unknown whether ZEPBOUND causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined”
Checked against the source on .Boxed warning — risk of thyroid C-cell tumors, on the second application as well. Mounjaro's approved labeling carries the same boxed warning as Zepbound's, in the same terms: rodent thyroid C-cell tumors of undetermined human relevance.
Recorded separately rather than merged with the Zepbound signal above, because the two approvals are two documents and this record's whole argument is that approval attaches to an application rather than to a molecule — so 'both products carry it' has to be two sources saying it, not one source and an inference. Retrieved 2026-07-16 via the openFDA drug/label endpoint, NDA 215866, effective_time 20260422. Mounjaro is likewise contraindicated in patients with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2.
MOUNJARO (tirzepatide) injection — Highlights of Prescribing Information — FDA, 22 April 2026“In both male and female rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether MOUNJARO causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined”
Checked against the source on .Labeled warnings and precautions: acute pancreatitis; hypoglycemia with concomitant insulin or insulin secretagogues; serious hypersensitivity reactions including anaphylaxis and angioedema; acute kidney injury due to volume depletion; severe gastrointestinal adverse reactions; diabetic retinopathy complications; acute gallbladder disease; and pulmonary aspiration during general anesthesia or deep sedation.
From the approved labeling, sections 5.2-5.9, retrieved 2026-07-16. Most common adverse reactions (>=5%): nausea, diarrhea, decreased appetite, vomiting, constipation, dyspepsia and abdominal pain. Severe Gastrointestinal Adverse Reactions (5.6) is flagged as a Recent Major Change dated 12/2025, and the drug is not recommended in patients with severe gastroparesis. These are the risks of the drug taken correctly under supervision — they are the floor, not the ceiling, for a product of unverified identity and content.
MOUNJARO (tirzepatide) injection — Highlights of Prescribing Information — FDA, 22 April 2026Checked against the source on .
Questions people actually ask
Every answer cites the document behind it. Where the honest answer is “nobody knows”, that is the answer you will get.
- Is tirzepatide FDA approved?
Yes — tirzepatide is FDA-approved as two Eli Lilly prescription products: Mounjaro (NDA 215866), indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years and older with type 2 diabetes, and Zepbound (NDA 217806), indicated with a reduced-calorie diet and increased physical activity to reduce excess body weight and maintain weight reduction long term in adults with obesity or overweight with a weight-related comorbid condition, and to treat moderate to severe obstructive sleep apnea in adults with obesity. Both were verified as active, prescription-only and not discontinued on Drugs@FDA on 2026-07-16. The approval attaches to those two applications, not to the molecule — tirzepatide sold by anyone other than the holder of an approved application is not an approved drug, and no approval covers anti-aging, body recomposition or general non-obese weight loss.
MOUNJARO (tirzepatide) injection — Highlights of Prescribing Information — FDA, 22 April 2026Checked against the source on .- Is it legal to buy tirzepatide from a peptide website?
No. FDA told USApeptide.com on 2025-02-26 that although 'there are FDA-approved tirzepatide products on the market in the U.S., there are no approved drug applications pursuant to section 505 of the FD&C Act in effect for' the tirzepatide it was selling, making those products unapproved new drugs whose introduction into interstate commerce violates sections 301(d) and 505(a). FDA also found them misbranded under section 502(f)(1): approved tirzepatide is available only by prescription, and 'because the aforementioned drugs are prescription drugs intended for conditions that are not amenable to self-diagnosis and treatment by a layperson, adequate directions cannot be written such that a layperson can use the products safely for their intended use.' The 'research use only' and 'not for human consumption' labels do not change this result — FDA held that despite those statements, 'evidence obtained from your website establishes that certain products offered for sale … are drugs intended for human use', and the sentences it cited as that evidence were the site's own accurate descriptions of what the APPROVED drug does.
Warning Letter — USApeptide.com (696885) — FDA, 26 February 2025“Despite statements on your product labeling and website such as "research use only," "not for human consumption," "lab purposes only," and "not intended to diagnose, cure, mitigate, treat or prevent disease," evidence obtained from your website establishes that certain products offered for sale by www.usapeptide.com are drugs intended for human use.”
Checked against the source on .- Can I still get compounded tirzepatide in 2026?
FDA proposed on 2026-05-01 not to add tirzepatide to the 503B Bulks List, which is the list of bulk substances outsourcing facilities may compound from, and its stated reason was that the approved drug is adequate: FDA 'tentatively finds no basis to conclude that there is an attribute of the FDA-approved drug products containing tirzepatide that makes them medically unsuitable to treat certain patients for a condition that FDA has identified for evaluation.' The shortage rationale that supported the 2023-2024 compounded-tirzepatide market is gone — FDA recorded that 'as of the date of this notice, FDA-approved tirzepatide drug products are not on the FDA drug shortage list', and said it 'does not interpret such issues, such as shortages and backorders, to be within the meaning of clinical need'. The proposal is not final: comments were due 2026-06-30. Eli Lilly filed a comment opposing the nomination (FDA-2015-N-3469-0404, 2024-11-04).
List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B of the Federal Food, Drug, and Cosmetic Act (Docket No. FDA-2018-N-3240) — Federal Register / FDA, 1 May 2026“This notice identifies three bulk drug substances that FDA has considered and proposes not to include on the 503B Bulks List: semaglutide, tirzepatide, and liraglutide.”
Checked against the source on .- Is oral or sublingual tirzepatide legit?
No tirzepatide drug product is FDA-approved in the oral, sublingual or buccal routes — FDA stated exactly that on 2026-05-01 while refusing to find a clinical need for compounded versions of them, rejecting the nominators' arguments that injections cause 'patient discomfort', require refrigerated storage and 'may lead to adherence failure'. FDA's answer was that 'the statutory standard for inclusion of a substance on the 503B Bulks List is clinical need--not "preference"', and that 'the potential for a patient to experience "discomfort" after receiving an injection does not mean that injectable product is medically unsuitable for the patient.' Every approved tirzepatide product — Mounjaro and Zepbound, in pens and in vials — is a solution for subcutaneous injection.
List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B of the Federal Food, Drug, and Cosmetic Act (Docket No. FDA-2018-N-3240) — Federal Register / FDA, 1 May 2026“We address here the proposals for oral, ``oral sublingual,'' and buccal products because no tirzepatide drug product is approved in these routes of administration.”
Checked against the source on .- Is research-grade tirzepatide the same as Mounjaro?
Not established, and FDA's inspection of one supplier is the reason to doubt it. FDA inspected Harbin Jixianglong Biotech Co., Ltd., a Chinese manufacturer of tirzepatide API shipped to the United States, in November 2025 and issued a warning letter on 2026-05-01 concluding that its APIs are adulterated under section 501(a)(2)(B) because its methods, facilities or controls do not conform to CGMP. FDA recorded that the firm shipped lots of tirzepatide API to the U.S. market in 2024 without completing analytical method validation for assay, related substances, high molecular weight aggregates and amino acid ratio, and in 2025 without completing method verification for the bacterial endotoxin test — the tests that establish, respectively, how much tirzepatide is there, what else is there, whether it is the right peptide, and whether it is safe to inject. The firm told FDA its tirzepatide API was 'in the development stage and full validation of all analytical methods has yet to be completed.' This is one supplier on one inspection and does not describe every vial on the market; it does mean that a 'research grade' label is a statement about intended use, not a measurement of identity or purity.
Warning Letter 320-26-73 — Harbin Jixianglong Biotech Co., Ltd. (723330) — FDA, 1 May 2026“Because your methods, facilities, or controls for manufacturing, processing, packing, or holding do not conform to CGMP, your APIs are adulterated within the meaning of section 501(a)(2)(B) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. 351(a)(2)(B).”
Checked against the source on .