Endotoxin Testing for Peptides: How the LAL Method Works and What EU/mg Means

On 21 October 2025, FDA classified a Class I recall of an NAD+ injection for endotoxin contamination — its most serious category. Endotoxin is bacterial lipopolysaccharide, it survives sterilisation, and on most certificates in this market the field reporting it is blank.

That recall is the only documented harm in the NAD+ category, and it is the clearest evidence available that pyrogen testing is not a formality on injectable material. NAD+ sits in the immune support and longevity peptides category; the companion test on a different axis is covered in peptide sterility testing under USP 71, and the document-level failures in red flags in peptide certificates of analysis.

What happened in the October 2025 NAD+ endotoxin recall?

FDA classified a Class I recall of NAD+ injection produced by GenoGenix on 21 October 2025, for endotoxin contamination. Class I is FDA's most serious recall category, reserved for products where there is a reasonable probability that use will cause serious adverse health consequences or death. Endotoxin causes fever, hypotension and, at sufficient dose in an intravenous product, septic shock. It is the only documented harm in the entire NAD+ category.

Everything else about NAD+ is an efficacy argument. This is not. The compound has been through repeated well-conducted randomised trials in which the biomarker rises reliably and downstream outcomes come back null, and intravenous NAD+ performed worse than intravenous nicotinamide riboside, with more adverse events. Against that background of measured nothing, one product category produced a real regulatory action, and the reason was contamination rather than pharmacology.

The NAD+ price page now shows zero shops with product in stock (verified August 2026), against 306 recency-weighted tests on file. Whether that reflects the recall, supply disruption or shifting demand, the data cannot say. The NAD+ compound page carries the listing history behind both figures.

What is endotoxin, and why does sterilisation not remove it?

Endotoxin is bacterial lipopolysaccharide — a structural component of the bacterial cell wall rather than a living organism — and killing or filtering out the bacteria does not remove what the bacteria left behind. It survives sterilisation. That single property is why sterility and endotoxin are two different tests answering two different questions, and why a vendor's assurance that material was filtered says nothing about pyrogen load. A sterile vial can carry a pyrogenic dose of endotoxin and pass every sterility check applied to it.

The consequence for a buyer is a reading rule rather than a chemistry lesson. A sterile-filtration step upstream is a claim about organisms. An LAL result is a measurement of the residue those organisms leave whether or not they are still alive at the point of filling. Nothing downstream of manufacture removes endotoxin, and nothing a buyer does at reconstitution removes it either — see reconstituting peptides step by step and the reconstitution calculator for what that stage can and cannot fix.

How is endotoxin testing different from sterility testing?

They answer different questions and neither substitutes for the other. Sterility asks whether viable organisms are present; endotoxin asks whether bacterial lipopolysaccharide is present, including from organisms that are already dead. Because endotoxin survives sterilisation, a product can pass sterility and fail endotoxin, which is exactly the failure mode the October 2025 Class I recall describes. Purity testing sits outside both questions entirely, since HPLC reports the proportion of total peak area attributable to one analyte and detects neither organisms nor pyrogens.

Sterility is the natural rival test here, and the pairing is the whole point rather than a technicality. The two are commissioned together on pharmaceutical injectables and separately, or not at all, on research-market vials. What USP <71> establishes on its own terms is set out in peptide sterility testing under USP 71.

What does an LAL result on a certificate actually look like?

A number in endotoxin units per millilitre, attached to a batch. Where results appear in this corpus they are small: Semax comes in at 0.05 to 0.096 EU/mL where reported at all, and compliant thymosin alpha-1 samples pass at ≤0.05 EU/mL. Those are reported figures rather than a compendial threshold, since this fact base carries no limit table. What a buyer can verify is that a number exists, that it sits on their lot, and that it is not a sentence instead.

The distinction between a result and a statement is the practical half of reading one. A house line such as "meets endotoxin standards" is not a result: it names no figure, no batch and no laboratory. An LAL value on the same certificate as the purity figure, carrying the same lot number, is. The DSIP sourcing guide makes the same point in a compound-specific form — ask for the result on your lot number, not a general assurance.

How often is the endotoxin field left blank?

Most of the time, across nearly every compound this platform tracks. Thymalin reports an endotoxin result on 2 of 12 displayed tests. Follistatin reports one across seven tests. Melanotan II's endotoxin results are mostly absent across a dataset of 251 independent tests, Semax appears on a minority of listings, and tesamorelin, sermorelin and survodutide entries mostly report nothing at all. The pattern holds so consistently that a filled field is the exception worth noticing rather than the default.

Read the last four rows against the first two. This is not a gap concentrated in obscure compounds — it runs through the best-covered entries on the platform, including one with 251 tests behind it, and through compounds sold explicitly for subcutaneous injection.

Why does FDA keep raising immunogenicity and endotoxin in the same sentence?

Because the agency's published objections to compounded peptides are characterisation objections, and endotoxin is one of the fields it names as missing. FDA's language recurs almost verbatim across substances: compounded drugs containing a given peptide "may pose risk for immunogenicity for certain routes of administration due to the potential for aggregation and peptide-related impurities." On ipamorelin, the agency went further and called the free base "not well-characterized from the physical and chemical characterization perspective," missing impurities, aggregates and endotoxin data outright.

Two of the agency's assessments name the microbial axis explicitly. On epitalon, FDA recorded missing data on "peptide related impurities and aggregates, microbial quality (bioburden, bacterial endotoxins)." On Semax, it described both forms as "not well-characterized", with missing impurity, aggregate, endotoxin and bioburden data, and raised "potential for immunogenicity associated with these impurities and peptide related aggregates."

"Compounded drugs containing thymosin-alpha-1 (Ta1) may pose significant risk for immunogenicity for certain routes of administration and may have complexities with regard to peptide-related impurities and API characterization. The safety-related information is inadequate for the agency to sufficiently understand the extent of any safety issues raised by the proposed compounded drug."

That is a regulator saying it does not have the documents. An LAL result on a specific batch is the one thing a buyer can obtain that answers part of the objection on the record. The full sequence of determinations is tracked in the FDA peptide regulation timeline, and the manufacturing context in GMP versus non-GMP peptide manufacturing.

Which compounds carry the strongest reason to demand an LAL result?

Four categories, and the reasoning differs in each. Injectable NAD+ has a Class I recall on the record for this exact contaminant. Thymalin is an injectable derived from calf thymus tissue, where purity testing cannot perform its identity function and pyrogen contamination is the realistic failure mode. The Category 2 peptides — GHRP-2, GHRP-6, ipamorelin acetate and kisspeptin-10 — carry FDA's written immunogenicity concern. And PEG-MGF and LL-37 have no human exposure data at all.

The thymalin case is the sharpest of these and it inverts the usual advice. There, endotoxin and sterility testing carry more weight than purity testing, because purity testing cannot do its usual job on an undefined extract — the reasoning is set out in full in thymalin science.

What does a blank endotoxin field mean?

Untested, not passed. That is the single most consequential reading rule on this page. A certificate is a record of assays performed; an empty row records an assay that was not commissioned. Nothing about an absent LAL value implies a low result, a clean batch or a compliant process, and no inference at all runs from silence to safety. On a compound where the field is blank across most of the market, absence is the default rather than a signal about one vendor.

The corollary matters as much. A filled field on a different batch is also not a result for the vial in hand, because endotoxin is a property of a production lot rather than of a product line. Ask for the number on your lot. If a vendor supplies a certificate for a batch other than the one shipping, that is the same defect catalogued in red flags in peptide certificates of analysis.

What can an LAL result not tell you?

Almost everything else on the certificate. An endotoxin result establishes pyrogen load on one batch and nothing about identity, quantity, purity, salt form, chirality, folding or sterility. A vial can return a clean LAL figure while containing the wrong molecule, a fraction of the labelled mass, or a peptide that oxidised in storage. The test is narrow by construction, and its value comes from being the only assay that addresses its particular failure mode rather than from covering ground other tests already cover.

The last two rows are there to make the general point concrete. Every analytical test in this market has a blind spot, and endotoxin's is unusually wide because its question is unusually specific. That is an argument for reading the whole certificate, not for discounting the LAL row — the reverse error, treating a purity percentage as though it covered pyrogens, is the more common one. Full coverage of the two dominant assays sits in what HPLC testing measures and mass spectrometry for peptides.

Which endotoxin claims survive scrutiny?

Three hold, three fail and one is a category error. The Class I recall is documented, endotoxin does survive sterilisation, and the field is blank across most of this market — all three verifiable. What fails is the family of inferences people draw from a purity certificate: that a high purity figure speaks to pyrogens, that filtration removes endotoxin, and that an empty field means a batch passed. The category error is treating sterility and endotoxin as one test with two names.

What do 11,852 independent lab tests show about endotoxin reporting?

They show a market that measures purity thoroughly and pyrogens rarely. Melanotan II records 99.62% average purity across 251 independent tests from five named laboratories — ILS, MZ Biolabs, Kovera, Janoshik and Freedom Diagnostics — across 226 verified shops (verified August 2026), and endotoxin results on that compound are mostly absent. NAD+ holds 306 recency-weighted tests at 99.07 against a platform composite of 99.50 (verified August 2026), on a compound with a Class I recall for this exact contaminant.

Peptigrity tracks 530 shops, 11,852 independent lab tests, 118 peptides and 1,283 community reviews (verified August 2026), with trust scores weighted 50% community reviews and 50% independently verified lab purity. The limit on that, stated plainly because it is our own largest asset, is that the purity half of every trust score is blind to pyrogens. A vendor can hold an excellent score on this platform without a single LAL result on file, and the methodology behind the weighting is documented in how we calculate trust scores.

Melanotan II price data shows 69 shops in stock at a median of $3.80/mg, lowest $1.50/mg on a 10 mg vial (verified 10 August 2026). Those figures exclude shipping, taxes and customs, coupon codes, bulk tiers, multi-vial kits and account-gated pricing. Individual certificates are browsable in the independent lab tests database and vendor-level scores in community-verified shop reviews; listings sit on the melanotan II compound page.

The trial that would settle how much endotoxin is in this market

No study has bought research-market vials at random, run LAL on every one, and reported the distribution of results. Every endotoxin figure on this page comes from a certificate a vendor chose to publish, which is the most favourable possible sample. The recall establishes that contamination happens; nothing establishes how often. That gap is the reason this article describes reporting frequency rather than contamination frequency, and the two are not the same measurement.

What to ask for before the money moves

Five requests, and only one of them is the LAL result itself. Ask for the endotoxin figure on your lot number, the sterility statement, the purity certificate from a named third-party laboratory, a net content figure and the batch date — then check that every document names the same lot. The lot match is what converts a folder of certificates into evidence about the vial in front of you, and it is the check most often skipped because the documents look complete without it.

Two of those rows are about paperwork rather than chemistry, and they are the ones that fail most often. A vendor who supplies an LAL result for a batch other than the one shipping has supplied a document, not a measurement of your material.

Frequently Asked Questions

What is endotoxin in a peptide vial?

Endotoxin is bacterial lipopolysaccharide, a structural component of the bacterial cell wall. It is a pyrogen, meaning it causes fever, and at sufficient dose in an intravenous product it can cause hypotension and septic shock. It is not a living organism, which is why removing bacteria does not remove it.

Does sterile filtration remove endotoxin?

No. Filtration removes organisms; endotoxin is cell-wall material those organisms leave behind, and it survives sterilisation. This is the reason sterility and endotoxin are two separate tests on pharmaceutical injectables, and the reason a product can pass one and fail the other. The October 2025 NAD+ recall is that failure mode in practice.

What does a blank endotoxin field on a certificate mean?

It means the assay was not run. It does not mean the batch passed, that the result was low, or that the vendor considered it unnecessary. An absent result carries no information about the material at all, and on most compounds in this market a blank field is the default rather than an outlier.

What endotoxin numbers appear on peptide certificates?

Where results are reported at all, this corpus records Semax at 0.05 to 0.096 EU/mL and compliant thymosin alpha-1 samples passing at ≤0.05 EU/mL. Those are reported figures rather than a compendial limit, and no limit table appears in this fact base, so none is printed here.

Which peptide had an FDA recall for endotoxin?

NAD+ injection produced by GenoGenix. FDA classified the recall as Class I on 21 October 2025 for endotoxin contamination. Class I is the agency's most serious recall category, reserved for products with a reasonable probability of causing serious adverse health consequences or death.

Why does FDA mention endotoxin in its peptide compounding assessments?

Because its objections are characterisation objections and endotoxin is one of the fields it records as missing. The agency called ipamorelin free base "not well-characterized from the physical and chemical characterization perspective," lacking impurities, aggregates and endotoxin data, and recorded the same gap for Semax and epitalon alongside its standing immunogenicity language.

Browse the immune support and longevity peptides category, or our complete peptide guide with 118 compounds (verified August 2026). For mixing volumes on any injectable, use the reconstitution calculator. Compare shops through independent lab tests and community-verified shop reviews.

This article is for educational and informational purposes only and does not constitute medical advice. Peptides discussed may be investigational compounds not approved by the FDA (or equivalent regulators in your jurisdiction) for human use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.