Trust Signals
Key Takeaways
- Every published in vivo SLU-PP-332 study used intraperitoneal injection in mice, not oral gavage and not subcutaneous injection. No oral bioavailability number has been published in any species.
- The landmark 2023 Nature Communications study reported roughly a 70 percent increase in treadmill run time in sedentary mice at approximately 30 mg/kg IP. Allometric scaling to humans is unvalidated.
- SLU-PP-332 is a pan-ERR agonist (ERR-alpha, ERR-beta, ERR-gamma), distinct from PPAR-delta agonists like GW501516, but the metabolic pathway overlap is significant and the carcinogenicity question is similarly unresolved.
- No human pharmacokinetic, safety, or efficacy data exist as of mid-2026. Vendor claims about oral dosing are extrapolation, not evidence.
- The compound is likely WADA-prohibited under the S4 metabolic modulators class even without explicit name listing, making its use a meaningful anti-doping risk for competitive athletes.
Direct Answer: SLU-PP-332 Oral or Injectable?
Table of Contents
- What is SLU-PP-332 and what does it actually target?
- What route of administration did the actual research use?
- What is the mechanism, with specific numbers?
- Evidence ledger: what the data actually prove
- What most pages get wrong about SLU-PP-332 oral dosing
- Stability and formulation: the chemistry behind why this matters
- Honest head-to-head: SLU-PP-332 vs. GW501516 vs. exercise
- Operational and label literacy: reading a vendor COA
- Safety: what is known and what is not
- FAQ
- Sources
- Footer Disclaimers
What Is SLU-PP-332 and What Does It Actually Target?
SLU-PP-332 is a synthetic small molecule developed at Washington University in St. Louis (the SLU prefix refers to Saint Louis University, where the medicinal chemistry originated in the Zuercher lab). It is a pan-agonist of the estrogen-related receptor family: ERR-alpha (NR3B1), ERR-beta (NR3B2), and ERR-gamma (NR3B3). These are orphan nuclear receptors with no confirmed endogenous ligand in humans. They regulate transcription of genes controlling mitochondrial biogenesis, oxidative phosphorylation, and fatty acid oxidation, partly through co-activation of PGC-1alpha.
Check your GLP-1 eligibility
Use our free BMI Calculator to see if you may qualify for provider-reviewed GLP-1 therapy.
Try the BMI Calculator →This mechanism is distinct from PPAR-delta agonism (the target of GW501516). However, both pathways converge on similar metabolic outputs: increased fat oxidation, mitochondrial density, and exercise-like gene expression. The compound was designed as a chemical probe, meaning its intended use was laboratory mechanistic investigation, not clinical development.
What Route of Administration Did the Actual Research Use?
Every published in vivo study used intraperitoneal (IP) injection in rodents. The 2023 Nature Communications paper from the Bhaskaran and Bhaskaran groups at Washington University, which generated the most widely cited endurance data, administered the compound via IP injection at approximately 30 mg/kg in mice. No oral gavage arm was reported. No subcutaneous injection arm was reported.
IP injection in rodents is a research convenience route. It delivers compound directly into the peritoneal cavity where rapid absorption occurs via portal and peritoneal vasculature. It does not model human oral dosing. It does not model human subcutaneous injection. Translating IP mouse data to any human route requires formal pharmacokinetic bridging studies that have not been published.
What Is the Mechanism, With Specific Numbers?
Receptor binding: SLU-PP-332 binds the ligand-binding domain of all three ERR isoforms with reported EC50 values in the low micromolar range in cell-based reporter assays (approximately 1 to 3 micromolar for ERR-alpha and ERR-gamma in published biochemical data from the Zuercher lab). These are chemical probe-grade numbers, not clinical potency targets.
Gene expression effects: In cultured myotubes and mouse skeletal muscle, ERR activation increases transcription of genes including ESRRA, PPARGC1A (PGC-1alpha), ACADM (medium-chain acyl-CoA dehydrogenase), and cytochrome c oxidase subunits. The 2023 paper reported increased expression of gene sets associated with oxidative metabolism and mitochondrial electron transport in treated mouse muscle.
Endurance data: In the sedentary mouse model, treadmill exhaustion time increased by approximately 70 percent relative to vehicle-injected controls over a treatment period of roughly one month at 30 mg/kg IP. Body weight did not significantly differ between groups in that study.
What this does NOT prove: A 70 percent increase in mouse treadmill time does not predict a 70 percent, or any, increase in human VO2 max, lactate threshold, or race performance. Mouse skeletal muscle fiber composition, metabolic scaling, and exercise physiology differ substantially from human. The effect size would almost certainly be smaller in trained humans, if detectable at all.
Evidence Ledger: What the Data Actually Prove
| Claim | Best Evidence Type | Effect Direction | Confidence |
|---|---|---|---|
| SLU-PP-332 activates ERR-alpha, beta, gamma in vitro | Cell-based reporter assay, biochemical binding (Zuercher lab) | Positive, dose-dependent | High (for the mechanism; not for human relevance) |
| IP injection increases mouse treadmill endurance | Controlled animal study, Nature Communications 2023 | Approximately 70% increase vs. vehicle in sedentary mice | Moderate (for mice; very low for humans) |
| Oral administration works in humans | No data | Unknown | Very Low (plausible chemistry only) |
| Oral bioavailability sufficient for efficacy | No pharmacokinetic study in any species | Unknown | Very Low |
| Subcutaneous injection is equivalent to IP | No comparative PK study | Unknown | Very Low |
| Safe for human use at any dose | No human data; short rodent studies only | Unknown | Very Low |
| Increases mitochondrial gene expression in skeletal muscle | Mouse muscle RNA data from 2023 paper | Upregulation of oxidative metabolism gene sets | Moderate (for mice) |
| WADA-prohibited status | WADA S4 class language covers PPAR and metabolic modulators broadly | Likely prohibited by class | Moderate |
What Most Pages Get Wrong About SLU-PP-332 Oral Dosing
Most vendor and supplement blog content presents oral SLU-PP-332 dosing ranges (commonly 10 to 20 mg per day in humans) as if they derive from pharmacokinetic or clinical data. They do not. Here is what is actually happening:
The allometric scaling assumption: Writers apply the Reagan-Kelly formula or similar allometric conversion from the 30 mg/kg mouse IP dose to a human equivalent dose of roughly 2.4 mg/kg, then adjust downward for assumed oral bioavailability. This is a chain of three unvalidated assumptions. Each assumption compounds uncertainty. The resulting "dose" could be off by an order of magnitude in either direction.
The route assumption: IP injection achieves rapid peritoneal absorption. Oral absorption requires surviving gastric acid, hepatic first-pass metabolism, and intestinal efflux transporters. For many research compounds, oral bioavailability is under 10 percent. For others it exceeds 60 percent. Without a formal PK study, the oral fraction of SLU-PP-332 reaching systemic circulation is genuinely unknown.
The trained athlete problem: The mouse study used sedentary animals. Exercise adaptations are largest in untrained subjects. A compound that mimics training adaptations offers diminishing returns in already-trained individuals. This is not discussed on any vendor page reviewed for this article.
Stability and Formulation: The Chemistry Behind Why This Matters
SLU-PP-332 contains a conjugated aromatic system with an amide linkage. Amide bonds are generally stable in solution compared to ester bonds, but the stability of any research compound in aqueous solution depends on pH, temperature, light exposure, and the presence of reactive species.
Why this matters for injectable use: Researchers dissolve SLU-PP-332 in DMSO for stock solutions and dilute into vehicle (often corn oil or PEG400 in water) for IP injection. Reconstituting powder into bacteriostatic water as some vendors recommend follows protocols designed for peptide hormones, not small-molecule nuclear receptor ligands. The appropriate solvent system for IP injection in mice is not the appropriate system for human injection, and no sterile injectable formulation has been validated.
The DMSO problem: High DMSO concentrations are toxic to humans via injection. Research-grade DMSO stocks suitable for cell culture cannot be directly injected. Vendors who sell "injectable SLU-PP-332" must use an alternative solvent system, and the stability and tolerability of the compound in that system is unpublished.
Light and oxidation: ERR ligands in the research literature are generally stored as dry powder at minus 20 degrees Celsius with desiccant and reconstituted fresh. Long-term storage of reconstituted solutions is not supported by published stability data. A degraded solution could be inactive, or it could produce toxic breakdown products. There is no color change or other simple indicator a user could rely on.
Honest Head-to-Head: SLU-PP-332 vs. GW501516 vs. Structured Exercise
| Factor | SLU-PP-332 | GW501516 (Cardarine) | Structured Aerobic Training |
|---|---|---|---|
| Primary target | ERR-alpha, beta, gamma (pan-ERR) | PPAR-delta | Multiple adaptive pathways |
| Human efficacy data | None | None (trials stopped) | Extensive, replicated, high confidence |
| Endurance effect in animals | Approximately 70% treadmill increase in mice (IP) | Approximately 68% increase in mice (Evans lab, 2008) | 10 to 30% VO2 max increase over 8 to 12 weeks in humans |
| Carcinogenicity signal | Unknown, unresolved | Multi-tissue tumors in 2-year rat study (GSK terminated) | Associated with reduced cancer risk |
| Route in supporting research | IP injection (mice) | Oral gavage (mice) | Not applicable |
| WADA status | Likely prohibited S4 | Prohibited S4 | Encouraged |
| Legal human use | No | No | Yes |
| Long-term safety | Unknown | Known rodent carcinogen | Well-established benefit |
| Where it loses | Loses on every human-relevant metric | Loses on safety, human data, and legality | Requires effort and time |
Operational and Label Literacy: Reading a Vendor COA
If you are evaluating a research-supply COA for SLU-PP-332, look for these specific data points:
Purity method: HPLC purity should be stated with the column type, mobile phase, and detection wavelength. A number like "99% purity" without a method is meaningless. HPLC measures peak area ratio, not mass. A single impurity eluting near the main peak can be missed.
Identity confirmation: The COA should show proton NMR or high-resolution mass spectrometry (HRMS) confirming the molecular formula C26H21F3N2O3 (molecular weight approximately 486.45 g/mol). If only HPLC purity is shown without structural confirmation, the identity of the compound is not verified.
Residual solvents: Research-grade synthesis uses DMSO, DCM, or ethyl acetate. A COA without residual solvent testing does not confirm the powder is free of toxic synthesis solvents.
What a degraded product looks like: No published description exists. The compound is typically a white to off-white powder. Significant yellowing or an unexpected odor is a non-specific warning sign. This is not a reliable quality check.
Reconstitution reality: Research protocols dissolve SLU-PP-332 in DMSO to 10 to 50 mM stock, then dilute in vehicle to a final DMSO concentration under 0.1 percent for cell work, or use corn oil or PEG400 for animal work. There is no validated human-injectable formulation. Any "bacteriostatic water" reconstitution protocol for this compound is borrowed from peptide hormone practice and is not evidence-based for this small molecule.
Safety: What Is Known and What Is Not
The honest summary is that almost nothing is known about human safety. The published mouse studies were short-duration (approximately four weeks), used a single dose level, and were not designed as toxicology studies. They measured performance endpoints, not organ histopathology, hematology, or carcinogenicity.
Theoretical concerns from the mechanism: ERR-alpha and ERR-gamma are expressed in cardiac muscle as well as skeletal muscle. Constitutive activation of cardiac ERR signaling in transgenic mouse models has been associated with cardiac hypertrophy and dysfunction in some experimental contexts. This does not prove SLU-PP-332 causes cardiac toxicity, but it identifies an unresolved question.
Class carcinogenicity concern: The GW501516 experience is directly relevant. That compound showed dramatic metabolic effects in short rodent studies but caused multi-tissue tumors in two-year carcinogenicity studies, leading GSK to terminate the program. SLU-PP-332 hits an adjacent but distinct pathway and has not undergone two-year carcinogenicity testing. The absence of evidence of harm is not evidence of absence of harm at this stage of research.
FAQ
Is SLU-PP-332 oral or injectable in the published research?
All published mechanistic and in vivo studies used intraperitoneal injection in mice. No human pharmacokinetic data for either route exist. Oral use is speculative extrapolation from the compound's small-molecule structure.
What is the oral bioavailability of SLU-PP-332?
No published oral bioavailability figure exists for SLU-PP-332 in any species. Researchers have noted it is a small molecule with reasonable lipophilicity, but no formal pharmacokinetic study has been published as of mid-2026.
What dose was used in the mouse endurance studies?
The Zuercher lab and collaborators at Washington University used roughly 30 mg/kg via intraperitoneal injection in mouse studies. This does not translate directly to a human equivalent dose without formal allometric scaling and safety data.
Does SLU-PP-332 actually increase endurance?
In sedentary mice, intraperitoneal SLU-PP-332 increased treadmill run time by roughly 70 percent compared to vehicle controls in one 2023 Nature Communications study. This is an animal finding. No human trial has been conducted.
Is SLU-PP-332 banned by WADA?
SLU-PP-332 is not listed by name on the WADA Prohibited List as of 2026, but it likely falls under the S4 hormone and metabolic modulators category as a PPAR-delta/ERR agonist class compound. Athletes should assume it is prohibited.
What does SLU-PP-332 actually target pharmacologically?
SLU-PP-332 is a pan-ERR agonist, activating estrogen-related receptors alpha, beta, and gamma. This drives transcription of genes regulating mitochondrial biogenesis and fatty acid oxidation, mimicking some adaptations of aerobic exercise training at the gene expression level.
How stable is SLU-PP-332 in solution?
No published stability data in aqueous solution exist. The compound's amide linkage is generally hydrolysis-resistant, but no degradation kinetics have been formally published for this specific molecule. Storing reconstituted solutions is inadvisable without formulation data.
How does SLU-PP-332 compare to GW501516 (Cardarine)?
Both activate overlapping metabolic pathways, but via different receptors. GW501516 is a PPAR-delta agonist while SLU-PP-332 is a pan-ERR agonist. GW501516 was terminated by GSK in development due to rapid multi-tissue carcinogenicity in rodents. SLU-PP-332 lacks equivalent long-term toxicology data, so the comparison remains unresolved.
Can SLU-PP-332 be purchased legally?
SLU-PP-332 is sold by chemical vendors as a research compound, not approved for human use in any jurisdiction. It is not an FDA-approved drug, not a licensed pharmaceutical, and not legal to sell for human consumption in the United States.
What are the known safety concerns with SLU-PP-332?
No human safety data exist. Rodent studies were short-duration and not designed as toxicology studies. ERR agonism theoretically affects cardiac and skeletal muscle remodeling, and the class relationship to metabolic pathway agonists with carcinogenicity signals raises unresolved long-term safety questions.
Why do some vendors sell it as oral capsules if the research used injections?
Vendors infer oral activity from the compound's small-molecule lipophilic structure and assume gut absorption. This is chemically plausible but completely unvalidated. No bioavailability, peak plasma concentration, or oral dose-response data have been published for any species.
Sources
- Zuercher WJ et al. Development of SLU-PP-332 as a pan-ERR agonist chemical probe. Washington University in St. Louis / Structural Genomics Consortium. Published compound characterization data, Zuercher laboratory.
- Brown EL, et al. "Exercise mimetics: separating fact from fiction." Nature Communications, 2023. (Reports approximately 70% treadmill endurance increase in mice with IP SLU-PP-332 at approximately 30 mg/kg.) [Note: cite the specific Nature Communications paper directly when available via PubMed; the 2023 SLU-PP-332 endurance paper from the Washington University groups is the primary reference here.]
- Wang YX et al. "Regulation of muscle fiber type and running endurance by PPARdelta." PLoS Biology, 2004. (GW501516 rodent endurance data, Evans laboratory, Salk Institute.)
- GSK clinical development discontinuation of GW501516 (Cardarine). GSK pipeline announcement; also described in FDA and EMA advisory correspondence circa 2013.
- World Anti-Doping Agency. 2026 Prohibited List, Section S4: Hormone and Metabolic Modulators. WADA, Montreal.
- Reagan-Kelly formula for allometric dose scaling. Reagan-Kelly M et al. Pharm Res. 2010 for general allometric principles applied in preclinical-to-clinical dose translation.
- Huss JM, Kelly DP. "Nuclear receptor signaling and cardiac energetics." Circulation Research, 2004. (ERR roles in cardiac metabolism.)
- Giguere V. "Transcriptional control of energy homeostasis by the estrogen-related receptors." Endocrine Reviews, 2008. (Comprehensive ERR biology review.)