In 2026, two of the world's most respected anti-doping laboratories published detailed chemical maps of what happens to SLU-PP-332 inside human liver tissue. One is in Los Angeles, the other in Cologne. Between them they catalogued dozens of breakdown products, worked out which ones a testing lab should hunt for in a urine sample, and published the mass-spectrometry signatures needed to do it.

Here is the odd part, and the reason this piece exists: not one human being has taken SLU-PP-332 in a clinical trial. The detection science has now run ahead of the efficacy and safety science. If you've been searching "what is SLU-PP-332" or "SLU-PP-332 research" and finding a lot of confident performance claims, this is the detail that reframes the whole picture — and it's the most concrete new development on this compound all year.

What is SLU-PP-332 — and why it isn't a peptide

First, a correction that most of the internet gets wrong. SLU-PP-332 is routinely listed on peptide vendor sites and lumped into "peptide" roundups, including our own peptides index where we file it for navigation reasons. It is not a peptide. It has no amino-acid chain. It's a synthetic small molecule developed at Saint Louis University (hence "SLU") that acts as a pan-agonist at the estrogen-related receptors ERRα, ERRβ and ERRγ — nuclear transcription factors that sit upstream of mitochondrial biogenesis and fatty-acid oxidation.

That distinction matters practically. Peptides and small molecules are regulated differently, metabolised differently, and behave differently when swallowed. SLU-PP-332 in particular is poorly orally bioavailable — it was used as an injectable tool compound in mice, which is precisely why the same lab went on to design SLU-PP-915, the orally active successor built around a boronic-acid moiety.

The underlying biology is genuinely interesting. The rodent work describes increased oxidative muscle fibres, higher fat oxidation and improved treadmill endurance — the "exercise in a pill" framing that drives most of the search traffic. But every one of those outcomes is mouse data. There are no human trials, no published human pharmacokinetics, and no regulatory approval anywhere in the world. Our full SLU-PP-332 profile walks through that evidence base in detail.

Two labs, one compound: the 2026 metabolite maps

22 metabolites in Los Angeles

Avliyakulov, Sobolevsky and Ahrens at the UCLA Olympic Analytical Laboratory — one of WADA's accredited testing labs — incubated SLU-PP-332 with pooled human liver S9 fractions and analysed the products by liquid chromatography–high-resolution mass spectrometry. They reported 22 metabolites: five monohydroxylated, three dihydroxylated, four reduced dihydroxylated, plus a set of glucuronide and sulfate conjugates formed on the naphthalene or phenolic rings. Eight of those were abundant enough to flag as candidate markers for doping control.

Nine metabolites in Cologne

Independently, Möller, Krug and Thevis at the Center for Preventive Doping Research at German Sport University Cologne (working with EuMoCEDA) characterised both SLU-PP-332 and SLU-PP-915 using human liver S9 fraction and human liver microsomes. For SLU-PP-332 they identified nine metabolites — six Phase I and three Phase II conjugates. For SLU-PP-915 they found seven, all Phase I, with selected structures confirmed by NMR. The parent compound was detectable as [M+H]⁺ at m/z 291.1142.

Why the two counts differ — and what they don't prove

The gap between 22 and 9 isn't a contradiction; it reflects different enzyme systems, incubation conditions and reporting thresholds. What matters more is the shared limitation both papers state plainly: these are in vitro results. Liver fractions in a tube are a model of human metabolism, not a measurement of it. Neither study analysed urine or blood from a person who had actually taken the compound, because no such authentic excretion samples exist in the public literature. The detection methods are a preventive scaffold, built in advance, waiting for real-world confirmation.

That's a genuinely unusual state of affairs: we now know more about how SLU-PP-332 would be found in a human than about what it would do in one.

Is SLU-PP-332 legal in Australia? The regulatory and anti-doping angle

Three separate layers, and they don't say the same thing.

Scheduling. SLU-PP-332 is not currently named in the Australian Poisons Standard. It's worth correcting a common confusion here: the entry people sometimes point to covers SR9009 and REV-ERB agonists — a different receptor family entirely. Being unscheduled is not an endorsement. It reflects a compound too new and too obscure to have been assessed.

Therapeutic supply. There is no lawful pathway to supply SLU-PP-332 for human therapeutic use in Australia. It holds no ARTG registration, and with zero human trial data there is no realistic basis for a TGA Special Access Scheme or Authorised Prescriber application, both of which lean on some existing body of clinical evidence. Anything sold as "research-use-only" sits outside the therapeutic goods framework — and outside any quality assurance.

Sport. This is the sharpest edge. WADA's S0 category prohibits any substance with no current approval from any government health authority for human therapeutic use — precisely SLU-PP-332's situation. S0 substances are banned at all times, in and out of competition. Sport Integrity Australia applies the 2026 Prohibited List to every athlete under the Australian national anti-doping scheme, from Olympians down to club-level competitors in signatory sports. The two 2026 metabolite papers exist specifically so laboratories can enforce that. Australian athletes should read those publications as a statement of intent: the assay groundwork is done.

What a cautious reader should take from this

The honest summary is short. Mechanistically plausible, rodent-only, unreplicated in humans, unapproved everywhere, and now actively targeted by anti-doping chemistry. The compound's own developers moved on to SLU-PP-915 because SLU-PP-332 couldn't be taken orally — which tells you something about how the people closest to the molecule rate it as a finished product.

If you want the next development on this compound — including whether any human trial is ever registered — join our free updates list. We track primary literature and Australian regulatory movement, and we'll say so plainly when there's nothing new to report.

FAQ

Is SLU-PP-332 a peptide?

No. SLU-PP-332 is a synthetic small molecule that agonises the estrogen-related receptors ERRα, ERRβ and ERRγ. It contains no amino-acid chain and is frequently mis-filed as a peptide by retailers and content sites.

Is SLU-PP-332 legal in Australia?

It is not currently named in the Poisons Standard, but it has no ARTG registration and no lawful pathway for therapeutic supply in Australia. It is also prohibited in sport under WADA's S0 non-approved substances category, which Sport Integrity Australia enforces at all times.

Can drug testing detect SLU-PP-332?

Two accredited anti-doping laboratories published in vitro metabolite maps and mass-spectrometry methods for SLU-PP-332 in 2026. Those methods are built on human liver fractions rather than samples from dosed humans, so they await real-world confirmation — but the analytical groundwork is in place.

Are there any human trials of SLU-PP-332?

None. All efficacy findings — endurance, fat oxidation, insulin sensitivity — come from mouse studies. There is no published human pharmacokinetic or safety data and no approval in any jurisdiction.

Sources

This article is general information, not medical advice. SLU-PP-332 is an investigational small molecule with no human trials and no regulatory approval in Australia or any other jurisdiction. retatrutide.net.au is independent and does not sell or supply any compound discussed.