Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Head-to-head comparison of FOXO4-DRI and SS-31 — mechanism, side effects, legal status, and pricing.
FOXO4-DRI is a D-retro-inverso peptide designed to disrupt the FOXO4-p53 interaction in senescent cells. It is studied as a senolytic agent that selectively induces apoptosis in senescent cells while sparing normal cells.
SS-31 (elamipretide) is a mitochondria-targeted tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) developed by Hazel Szeto (Cornell) and clinically advanced by Stealth BioTherapeutics. It concentrates in the inner mitochondrial membrane by binding cardiolipin. In September 2025, the FDA granted accelerated approval to elamipretide (brand name FORZINITY) as the first therapy for Barth syndrome — the first FDA-approved mitochondria-targeted drug. It remains investigational for other indications.
FOXO4-DRI
SS-31
Category
Legal Status
Mechanism
Half-life
Side Effects
COA-verified vendors · trust score ≥70 required · single-vial price — bulk/bundle deals may be lower
FOXO4-DRI
SS-31
COA corpus from Disclosed Labs — independently tested batches only.
FOXO4-DRI
5
COAs
99.5%
Avg purity
4
Labs
SS-31
65
COAs
99.8%
Avg purity
12
Labs
Baar et al. (Cell, 2017, PMID 28340339) identified FOXO4 as a pivot for senescent-cell viability and designed a cell-penetrating D-retro-inverso peptide that disrupts the FOXO4-p53 interaction, selectively triggering apoptosis in senescent cells while sparing proliferating cells. In vivo, the peptide neutralized doxorubicin chemotoxicity and, in fast-aging XpdTTD/TTD and naturally aged mice, restored fur density, renal function, and fitness. This is the only primary in vivo study; evidence is preclinical only. No human clinical trials have been registered or completed. Safety in humans is unknown — as a systemic senolytic inducing apoptosis, theoretical risks include impaired wound healing, immune perturbation, and off-target effects on quiescent stem-cell populations.
The original SS-peptide class was described by Zhao, Szeto and colleagues (J Biol Chem 2004, PMID 15178689), showing ~1000-fold concentration at the inner mitochondrial membrane and protection against oxidative cell death. Szeto's 2014 review (Br J Pharmacol, PMID 24117165) reframed the mechanism as cardiolipin-binding rather than antioxidant scavenging. The TAZPOWER trial (NCT03098797) in Barth syndrome, with its 168-week open-label extension (Thompson et al., Genet Med 2024, PMID 38602181), supported FDA accelerated approval of FORZINITY in September 2025 at 40 mg SubQ daily. The Phase 3 MMPOWER-3 trial in primary mitochondrial myopathy (Karaa et al., Neurology 2023, PMID 37268435) FAILED co-primary endpoints of 6-minute walk test and fatigue score, though a post-hoc nuclear-DNA subgroup showed improvement. Phase 2 ReCLAIM-2 in geographic atrophy missed primary endpoints but reduced ellipsoid-zone attenuation; a Phase 3 trial is ongoing. Earlier heart failure trials (PROGRESS-HF) showed only modest signals.
FOXO4-DRI (Metabolic) and SS-31 (Recovery) are in different categories and target different biological pathways. This is a common pattern in multi-compound research protocols. Researchers should monitor the biomarkers from both profiles and watch for interactions listed in each compound’s contraindications. Consult a licensed healthcare provider before combining any research compounds.
This platform provides informational tools only, not medical advice. This comparison is for educational purposes only. Consult a licensed provider.
Contraindications
Lab Testing
Disclosed Labs