SLU-PP-332 Dosage Chart, Schedule & Reconstitution Protocol

Mechanism of Action (MOA)

SLU-PP-332 is a synthetic small molecule (not a peptide) developed at Saint Louis University as a pan-agonist of the estrogen-related receptors (ERRs), a family of orphan nuclear receptors comprising three isoforms—ERRα (NR3B1), ERRβ (NR3B2), and ERRγ (NR3B3). Despite their name, ERRs do not bind estrogen or estradiol; they are constitutively active transcription factors that adopt an active conformation in the absence of ligand and coordinate genes involved in mitochondrial biogenesis, oxidative phosphorylation, fatty acid oxidation, the tricarboxylic acid cycle, and substrate utilization in muscle, heart, and brown adipose tissue. ERRα is the central regulator of muscular energy metabolism and is essential for the molecular adaptations to endurance exercise [1]. Billon, Kahn, Burris and colleagues reported in 2023 that SLU-PP-332 binds and activates ERRα with an EC50 of approximately 98 nM, ERRβ with 230 nM, and ERRγ with 430 nM, making it the first reasonably potent synthetic ERR pan-agonist suitable for in vivo investigation. In skeletal muscle cell lines, SLU-PP-332 increases mitochondrial respiration, expression of genes encoding oxidative phosphorylation components, and fatty acid oxidation enzymes. In mice, eight to ten days of SLU-PP-332 administration produces an acute transcriptional signature similar to endurance exercise, including upregulation of PGC-1α, mitochondrial DNA-encoded oxidative phosphorylation genes, and slow oxidative myofiber markers [2]. Longer-term administration of SLU-PP-332 to mice produces several metabolically relevant effects. First, running endurance on treadmill tests improves by approximately fifty percent, accompanied by expansion of fast oxidative type IIa fibers and increased capillarization in skeletal muscle. Second, in diet-induced obese mice, SLU-PP-332 prevents weight gain and reduces fat mass without altering food intake, indicating that the mechanism involves increased energy expenditure rather than appetite suppression. Third, glucose tolerance and insulin sensitivity improve, and hepatic steatosis is reduced in non-alcoholic fatty liver disease models [3]. Mechanistically, ERRα activation drives transcription of nuclear-encoded mitochondrial genes through binding to ERR response elements (ERREs) in target promoters and through cooperative interactions with the transcriptional coactivator PGC-1α, which is itself induced by exercise. SLU-PP-332 thus pharmacologically engages the same transcriptional axis as exercise, justifying its description as an 'exercise mimetic.' It does not, however, replicate the cardiovascular, mechanical, or neurocognitive benefits of physical exercise, and its long-term safety in mammals is not well characterized. No human pharmacokinetic, safety, or efficacy data have been published. Rodent studies typically use SLU-PP-332 at 10–30 mg/kg intraperitoneally or orally once or twice daily, but no human-equivalent dose has been established, and the molecule has not entered formal clinical development. SLU-PP-332 is sold as a research chemical for laboratory investigation only and should not be used for human consumption or self-administration; importantly, ERR agonism could theoretically promote growth of ERR-dependent cancers, raising additional safety concerns for off-label use. Because SLU-PP-332 is a small-molecule oral compound rather than an injectable peptide, traditional peptide dosing protocols do not apply.