SLU-PP-332

What it is

SLU-PP-332 is not a peptide but a synthetic small molecule. It was developed by the research group of pharmacologist Thomas Burris; the abbreviation SLU stands for Saint Louis University, where the early work took place. In 2023 the team presented the substance as an agonist that switches on all three ERR receptors, most strongly ERRα. For research this was a step forward, because until then there were hardly any tools to activate these receptors selectively in the living animal.

In the scene, SLU-PP-332 is known as an exercise mimetic, that is, an exercise imitator, sometimes under the nickname “exercise in a syringe”. The interest comes from three directions: endurance athletes who want to amplify the training effect, people concerned with body composition and fat burning, and the longevity scene, for which healthy mitochondria are a central aging topic.

How it is supposed to work

The ERR receptors are called estrogen-related, but they do not bind the body’s own estrogen. They are transcription factors that control genes for new mitochondria, cellular respiration and fat burning, above all in the heart, skeletal muscle and liver. Their most important partner is the coactivator PGC-1α. You can think of PGC-1α as the conductor and the ERR receptors as musicians who translate its instructions into gene activity. Endurance training raises the baton; SLU-PP-332 makes the musicians play directly.

The research group examined this mechanism closely. In muscle cells, the substance increased cellular respiration and mitochondrial function. In mouse muscle it switched on a gene program similar to that after an acute bout of endurance exercise, led by the gene Ddit4, which is also activated during training. Mice genetically lacking ERRα in muscle did not benefit: their endurance stayed at the level of untreated animals. The effect therefore really does depend on the target receptor.

More than a sports topic

The medical vision goes far beyond sport. Exercise is one of the most effective means against metabolic diseases, but not everyone can train, for example after injuries, in severe illness or in old age. For these people, a molecule that delivers part of the training stimulus would be of interest. In a mouse model of heart failure, SLU-PP-332 and the sister compound SLU-PP-915 improved pumping function and survival. In 21-month-old mice, that is, animals of advanced age, an 8-week treatment reversed age-related kidney changes such as protein in the urine, mitochondrial weakness and inflammatory messengers.

There is also a first study with human cells. In 2025, researchers treated muscle precursor cells from physically inactive women receiving a hip replacement with SLU-PP-332 in the laboratory. The cells formed more PGC-1α and ERRα, showed less oxidative stress and formed abundant myotubes, the precursors of muscle fibers. This suggests that the mechanism also works in human tissue. It is not yet an effect in living humans.

What users report

The substance is sold as a research product and in the scene is sometimes injected, sometimes taken as a tablet. A rapidly noticeable endurance effect is consistently reported; some measure it by their own running or cycling times. That an effect appears quickly does not contradict the biology, because in the animal experiment a single dose one hour before running was already effective.

It remains open whether the amounts and routes common in the scene even reach active levels like those in the animal experiment. Nobody has measured this. Such reports are observations without a control group; expectation and normal fluctuations in training cannot be factored out. They are interesting, but not proof of efficacy.

What the studies show

Endurance in the mouse experiment (Billon, 2023)

The paper in ACS Chemical Biology introduced SLU-PP-332. Untrained mice received a single dose one hour before a treadmill test to exhaustion, with 6 animals per group. They ran around 70 percent longer and 45 percent farther. After longer dosing, grip strength and the proportion of oxidative type IIa fibers increased. Mice without ERRα in muscle showed no endurance gain after 14 days of treatment. The groups were small, and the animals received the substance into the abdominal cavity.

Overweight and metabolism (Billon, 2024)

In the Journal of Pharmacology and Experimental Therapeutics, the same group tested the substance in mice with diet-induced obesity and in genetically obese ob/ob mice. After 28 days, the treated overweight animals weighed around 12 percent less. The control animals gained about 5 grams of fat, the treated ones less than 0.5 grams. Food intake remained the same, the additional expenditure came from metabolism, and insulin sensitivity improved.

Heart failure in the animal model (Xu, 2024)

In Circulation, SLU-PP-332 and SLU-PP-915 improved ejection performance, reduced fibrotic remodeling and prolonged survival in mice with pressure-induced heart failure. This was mediated mainly via ERRγ and improved fat and energy metabolism of the heart muscle. The thickening of the heart muscle itself remained unchanged.

Where the data stop

All efficacy research comes from animals and cell cultures. A 2026 systematic review on SLU-PP-332 and SLU-PP-915 found exclusively preclinical studies and considers clinical trials necessary before anything can be said about efficacy and safety in humans. The efficacy data come predominantly from a research network around the same group; independent replications are rare.

Then there is absorption by mouth. The developers themselves write in 2026 that SLU-PP-332 is not orally bioavailable, and therefore presented the successor SLU-PP-915, which also works when swallowed. Tablets containing SLU-PP-332 therefore lack a basis. A review in Trends in Endocrinology and Metabolism also points out that training is far more than mitochondria: blood vessels, the autonomic nervous system, inflammation and messenger substances from muscle change as well. A pill that operates a single switch does not reproduce this overall package.

Status, approval and legal

SLU-PP-332 is not approved as a medicine anywhere and is in early preclinical research; no clinical trials have been published. It is sold as a research chemical without pharmaceutical quality control. In sport, as a non-approved, pharmacologically active substance, it falls under class S0 of the WADA Prohibited List 2026, which prohibits such substances at all times, including out of competition. It is not named there, but in 2026 doping laboratories already described its metabolites in human liver preparations in order to be able to detect misuse. We do not give doses for non-approved substances.

Safety

There are no safety data in humans. In animals, the research group found no obvious toxicity after 10 days of dosing; blood count, electrolytes and the muscle marker creatine kinase remained unremarkable. This is a short-term finding in a few mice and says nothing about months or years in humans. Because ERR receptors broadly reprogram the metabolism of the heart, liver, kidney and muscle, long-term consequences are difficult to predict. On interactions, pregnancy, and pre-existing conditions of the heart, liver or kidney, there are no data whatsoever. With research products, unclear purity and unclear content come on top.

Sources

• Billon C et al., ACS Chem Biol 2023
• Billon C et al., J Pharmacol Exp Ther 2024
• Xu W et al., Circulation 2024
• Wang XX et al., Am J Pathol 2023
• Bonanni R et al., Front Physiol 2025
• Billon C et al., J Pharmacol Exp Ther 2026 (SLU-PP-915)
• de Souza-Lima J et al., Rev Med Chil 2026 (systematic review)
• Plaza-Florido A et al., Trends Endocrinol Metab 2026
• Avliyakulov NK et al., Drug Test Anal 2026
• WADA Prohibited List 2026, official publication BGBl. III Nr. 219/2025