SLU-PP-332: The "Exercise Pill" Sold as a Peptide (It Isn't One)

SLU-PP-332 is not a peptide, and no human has taken it in a published trial. It is a small synthetic molecule, 290 daltons with the formula C18H14N2O2, and it contains no amino-acid chain at all¹⁰. It switches on a family of proteins called estrogen-related receptors (ERRs), and in mice it made sedentary animals run about 70% longer¹. That is the whole evidence base for the "exercise pill" label: rodents, injected into the abdomen, twice a day.

The finding that went the wrong way is about how it is sold. Some sellers offer it as a capsule. In 2026, the same research group that created SLU-PP-332 wrote that it "lacks oral bioavailability," and built a different compound, SLU-PP-915, to fix that⁵. A search of ClinicalTrials.gov for SLU-PP-332 returns zero registered studies¹¹.

What SLU-PP-332 actually does

The name sounds hormonal, and it is not. Estrogen-related receptors are "orphan" nuclear receptors, meaning no natural hormone is known to switch them on, and despite the name they are not estrogen receptors¹. They sit inside cells and turn on genes for mitochondria, fat burning and the energy cycle. Exercise raises their activity in muscle, which is why a drug that switches them on directly looked like a shortcut.

SLU-PP-332 was designed for that job as a laboratory tool. The developers' first paper describes it as having "sufficient pharmacokinetic properties to be used as an in vivo chemical tool"¹, which is a precise phrase: good enough to dose mice, not a drug candidate. A 2026 chemistry paper calls it "a well-established exercise mimetic and widely used chemical probe," and reports newer versions with better solubility and metabolic stability¹⁴. The research field has already moved past it. The compound sold online is the prototype.

What the two mouse papers measured

Paper one (2023): the endurance result. Researchers in St. Louis reported SLU-PP-332 as a "pan agonist" that activates all three ERRs, most strongly ERR-alpha¹. In muscle cells it raised mitochondrial function. In mice, it shifted muscle toward oxidative type IIa fibers. Sedentary mice given 50 mg/kg by intraperitoneal injection twice a day for seven days ran about 70% longer and 45% farther on a treadmill than mice given a placebo injection¹. The effect depended on ERR-alpha.

Paper two (2024): the weight result. The same group gave obese mice the same dose, by the same route, for 28 days². The mice burned more energy and more fat, gained far less fat mass, and improved insulin sensitivity. Diet-induced obese mice on the drug weighed about 12% less after 28 days. The study in genetically obese mice was cut to 12 days "due to reduced tolerance of twice per day intraperitoneal administration"².

Follow-up work has stayed in animals and dishes:

• •Heart. In mice with heart failure induced by pressure overload, SLU-PP-332 and its sister compound improved ejection fraction, reduced scarring and increased survival³.
• •Kidney. In 21-month-old mice, eight weeks of SLU-PP-332 reversed age-related protein leakage in the urine, loss of filtering cells and kidney inflammation⁴.
• •The successor. SLU-PP-915, built because SLU-PP-332 is not absorbed by mouth, matched its endurance effect in mice when swallowed, and further raised exercise-linked muscle gene activity when combined with treadmill training⁵. One 2025 study used muscle samples from 20 women having hip surgery, but the drug only touched cells in a dish, not the women⁶.

A 2026 systematic review of the whole literature said the same thing in its conclusion: "Clinical trials are needed to confirm their efficacy and safety in humans"¹³.

Why "exercise mimetic" does not mean what the label implies

"Exercise mimetic" is a lab term for a compound that switches on some of the same genes exercise does. It is not a promise that a person gets fitter without training. The phrase has been here before. In 2008, AICAR made sedentary mice run 44% longer after four weeks, and its authors called it an exercise mimetic too¹². It never became an approved endurance drug.

Three gaps sit between the mouse data and a capsule bought online:

• •Dose. 50 mg/kg twice a day in a mouse does not translate into a human dose by simple arithmetic, and nobody has run the human dose-finding study that would.
• •Route. Every endurance and weight result used intraperitoneal injection. The developers' own 2026 paper says SLU-PP-332 is not orally bioavailable⁵.
• •What is in the bottle. With no approved product and no reference standard sold to consumers, a buyer cannot confirm the contents. Our guide to vendor red flags covers why a certificate of analysis from the seller does not settle that.

For how this compares with the other two compounds sold on the same promise, see MOTS-c and endurance, which is at least a real peptide your own cells make, and 5-Amino-1MQ, another small molecule sold on peptide shelves.

Side effects: unknown in humans, so the honest list is short

There is no human safety data. That is not a figure of speech: no trial, no case series, no adverse event database entry tied to a known dose.

What the mouse papers report is narrow. The 2023 paper saw "no overt toxicity" over 10 days at the study dose, with normal blood counts, electrolytes and creatine kinase¹. The 2024 paper shortened one arm because the obese mice tolerated the twice-daily injections poorly².

Two things are known about how the human body handles it, both from liver tissue in test tubes. Anti-doping labs incubated SLU-PP-332 with human liver fractions and found 9 to 22 breakdown products, depending on the lab and method⁷⁸. Those studies exist to catch athletes, not to establish safety.

ERRs also run energy metabolism in the heart and kidney, which is why those mouse studies exist³⁴. Effects there were favorable in diseased mice. Nobody knows what years of ERR activation do to a healthy human heart.

Why it shows up on peptide shelves

SLU-PP-332 reached the peptide market for the same reason 5-Amino-1MQ did: the same research-chemical sites sell both, under a "for research use only" label, to the same buyers who come for BPC-157 and MOTS-c. Nothing about the chemistry connects them. A research-use label is not a quality standard, and it is not permission to take the product. Our explainer on where peptides are sold and what the research-chemical label means covers why that label exists and what it does not protect.

If you are weighing it anyway, these are the questions that have no answer yet:

• •What dose, if any, is active in a person?
• •Does anything reach the blood when it is swallowed?
• •What does it do to the heart, liver and kidneys over months?
• •Is the powder in the capsule actually SLU-PP-332, and how much of it?

Until a human study answers the first three, the fourth is the only one a buyer can even try to check, and a seller's own test sheet cannot settle it.

Anti-doping status

Do not guess here; read the rule. SLU-PP-332 has no approval for human therapeutic use from any health authority anywhere, which is the trigger for WADA's S0 class of non-approved substances, prohibited at all times⁹. Anti-doping labs in Los Angeles and Cologne have already published methods to detect it, and the Cologne group describes it as having "doping potential"⁷⁸. In plain terms: a tested athlete who takes it is taking a banned substance that labs are specifically looking for.

Run anything else you are considering through our prohibited-substance checker, and see the WADA list for peptides for how the classes work.

If what you want is a prescribed option

No licensed provider we review prescribes SLU-PP-332, and it has no route into a US compounding pharmacy: it is not an ingredient of any approved drug and is not on FDA's 503A bulks list. The closest thing a clinician will write is MOTS-c, the mitochondrial peptide sold on the same "exercise mimetic" pitch. Be clear about what that is: a compounded product, not FDA-approved, with mostly animal evidence, and banned in tested sport. Its regulatory picture is laid out in MOTS-c's FDA status.

What providers charge for it varies by more than double:

• •Telos Rx lists MOTS-c "as low as $116," says its prices depend on plan length, and names its compounding pharmacies with street addresses.
• •Magnolia Regenerative Medicine prices MOTS-C at $135 on its open catalog.
• •Live Vital sells MOTS-c at $149 a month.
• •ElitePhysiqMD charges $337.50 a month for MOTS-C on subscription.
• •Pepti prices MOTS-c at $339 for an average four-week supply, with cold-chain shipping included.

Every recovery-peptide provider we have checked is compared on our recovery peptide rankings.

The bottom line

SLU-PP-332 is an interesting research tool with good mouse data and nothing else. It is a small molecule, not a peptide. It worked by injection, not by mouth. It has never been tested in a person. And it is banned in sport, with detection methods already published. The "exercise pill" is, so far, a mouse that ran farther.