SS-31

SS-31 Peptide

SS-31 (Elamipretide/MTP-131) is a synthetic tetrapeptide that selectively concentrates in the inner mitochondrial membrane, binding cardiolipin to stabilize the electron transport chain — mechanistically distinct from AMPK-activating and NAD-replenishing longevity approaches, acting directly at the membrane level rather than through metabolic signaling pathways. Licensed practitioners looking to buy SS-31 can contact Medical Spa Rx’s professional support team for guidance on sourcing from qualified suppliers and for access to supporting documentation, including purity information. Browse this page to learn more about the SS-31 peptide and its research applications, including an overview and FAQs.

SS-31 Peptide Benefits: Exercise Tolerance, Cardiac & Skeletal Muscle

SS-31 (Elamipretide/MTP-131) is a mitochondria-targeting synthetic tetrapeptide with the sequence D-Arg-Dmt-Lys-Phe-NH2. It concentrates in the inner mitochondrial membrane and binds cardiolipin to stabilize electron transport chain complexes and reduce mitochondrial reactive oxygen species. As a longevity and anti-aging peptide, it is evaluated for mitochondrial dysfunction, oxidative stress, exercise tolerance, cardiac and skeletal muscle protection, and renal injury. Its mechanism differs from NAD-based and AMPK-mediated approaches. SS-31 acts directly at the membrane level, not through metabolic signaling pathways.

Primary Mitochondrial Myopathy (PMM) & Exercise Tolerance

Clinical studies on SS-31 support a cautious interest in exercise tolerance rather than broad claims of efficacy. Human data remain highly mixed:

• 2018 Dose-Escalation Trial: Karaa et al. reported that short-term IV elamipretide showed numerical improvement in six-minute walk distance (64.5m vs 20.4m placebo) in adults with PMM, though this did not reach statistical significance for the 6MWT endpoint (p=0.053).[2]
• 2023 Phase 3 Trial (MMPOWER-3): Karaa et al. (Neurology, 2023) evaluated a larger population over 24 weeks. The trial failed to meet its primary endpoint in the overall study population. Notable genotype-specific effects were observed only in nuclear DNA deletion subgroups.[1]

Cardiac Care & Heart Failure

Cardiac interest is driven by the same membrane-stabilizing mechanism, yielding mixed clinical trial endpoints:

• Acute IV Infusion: Daubert et al. (Circ Heart Fail, 2017) tested a single 4-hour IV infusion in patients with HFrEF. The treatment was safe and well tolerated, with favorable short-term changes in left ventricular volumes in the highest-dose cohort.[4]
• Chronic Subcutaneous Dosing: The PROGRESS-HF trial (Butler et al., J Card Fail, 2020) evaluated repeated daily subcutaneous dosing over 4 weeks in patients with stable HFrEF. While well tolerated, it did not significantly improve left ventricular end-systolic volume compared to placebo (4 mg vs placebo: p=0.90; 40 mg vs placebo: p=0.28).[3]

Renal Protection

SS-31 demonstrates protective effects in animal models of acute kidney injury and chronic kidney disease, targeting tissue injury driven by mitochondrial dysfunction and oxidative stress. These data support the peptide’s overarching biological rationale. All renal applications must be framed as extrapolated from preclinical research rather than clinically validated.

SS-31 and Mitochondrial Dysfunction: Cardiolipin-Binding Mechanism

The central question of what the SS-31 peptide does is answered by its cardiolipin-binding action in the inner mitochondrial membrane. Elamipretide selectively concentrates at that membrane at approximately 1,000 times plasma concentration — a unique pharmacokinetic property that enables targeted membrane-level action. It associates with cardiolipin, stabilizes electron transport chain complex assembly, and anchors cytochrome c interactions, preserving both ATP synthesis efficiency and mitochondrial membrane potential.

The cascade that SS-31 interrupts is well characterized: aging and disease oxidize cardiolipin, disrupt ETC complexes, increase electron leak, and amplify mitochondrial reactive oxygen species. By targeting this process at the source, SS-31 may preserve membrane potential, improve ATP efficiency, and reduce oxidative stress before it propagates downstream into inflammatory and cellular damage pathways. This upstream structural action is the central differentiator from AMPK-mediated and NAD-centered longevity strategies. Preclinical findings suggest that SS-31 may reverse established mitochondrial dysfunction in animal models. This reversal has not been demonstrated in human trials. Human efficacy remains indication-specific and mixed.[1],[2]

SS-31 Dosage, Administration & Storage

The SS-31 peptide dosage discussion requires that the clinical distinction between IV and subcutaneous routes be clearly maintained. In published investigational studies, IV elamipretide was administered at approximately 0.005 to 0.25 mg/kg/h over 4 hours, producing the earliest controlled human efficacy and safety signals in mitochondrial and cardiac populations.[2],[4] These values are derived from specific trial protocols and should not be generalized beyond those contexts.

Later clinical programs and the FDA-approved Barth syndrome product used once-daily subcutaneous dosing, including 40 mg regimens in the approved labeling.[5] Outside approved Barth syndrome use, subcutaneous SS-31 dosage for off-label applications remains practitioner-reported or extrapolated from preclinical data, with no standardized human protocol validated for off-label use. Individualized assessment is required.

Storage for lyophilized SS-31 generally requires cold-chain handling at approximately -20 °C. After reconstitution with bacteriostatic water, refrigeration at 2 to 8°C is recommended, with protection from light and use within the stability window specified by the supplier. Lot-specific purity documentation should accompany every batch.

SS-31 Peptide vs MOTS-c & SS-31 Peptide vs NAD

SS-31 and MOTS-c address mitochondrial longevity through highly complementary mechanisms. SS-31 acts at the structural level by binding cardiolipin, stabilizing the inner membrane, and preventing the generation of mitochondrial reactive oxygen species at the source. MOTS-c is a mitochondria-derived peptide that transfers to the nucleus in an AMPK-dependent manner and binds transcription factors regulated by antioxidant response elements (ARE), modulating mitochondria-to-nucleus communication to regulate metabolic adaptation, insulin sensitivity, and exercise-related substrate use. Practitioners evaluating established structural membrane instability or severe oxidative stress often prioritize SS-31. MOTS-c is more relevant for metabolic aging and exercise performance protocols.

Because SS-31 addresses structural membrane protection and MOTS-c targets the downstream metabolic signaling layer, the two mechanisms are additive rather than redundant in comprehensive longevity protocols. Together, they cover upstream membrane integrity and downstream signaling adaptation within the same mitochondrial biology framework. Researchers evaluating these overlapping pathways can consult Medical Spa Rx’s professional support team for guidance on verified sourcing documentation, including for those who choose to buy MOTS-c alongside SS-31.

Compared with NAD-centered strategies, SS-31 operates further upstream to shield structural elements before oxidative damage cascades downstream. NAD approaches focus on replenishing coenzyme substrates to power sirtuin-mediated DNA repair, PARP activation, and mitochondrial biogenesis. Stacking these interventions provides a logical research rationale: SS-31 protects the membrane and limits mROS at the source, while NAD powers the downstream cellular repair machinery. This distinct biological division allows practitioners to target membrane stability with one agent and cofactor replenishment with the other.

For practitioners evaluating both layers of this protocol, sourcing guidance and documentation are available for those who choose to buy NAD through Medical Spa Rx’s professional support team.

SS-31 Safety Profile & Legal Status

Across published clinical studies, elamipretide has been generally well tolerated.[1],[2],[3],[4] Injection-site reactions are the most commonly reported adverse events in subcutaneous studies, and IV programs have shown acceptable short-term tolerability with mild flushing or nausea at higher infusion rates. Long-term safety outside studied populations remains less characterized, and safety discussions should remain evidence-qualified and indication-specific.

As of June 2026, elamipretide is FDA-approved under the brand name Forzinity for Barth syndrome in patients weighing at least 30 kg, following FDA accelerated approval granted on September 19, 2025.[5] For primary mitochondrial myopathy, heart failure indications, renal applications, and broader longevity protocols, SS-31 remains investigational or off-label. Practitioners must maintain explicit on-label versus off-label distinctions in all protocol discussions, as of June 2026. SS-31 is not currently on the WADA Prohibited List as of June 2026, though athletes should verify current status independently before any use.

Where Can Practitioners Buy SS-31 Online?

Practitioners looking to buy SS-31 online should source exclusively from suppliers who provide verifiable purity documentation, LOT number traceability, and a certificate of analysis. Given that subcutaneous SS-31 use outside the approved Barth syndrome labeling is research-extrapolated and lacks a standardized human protocol, quality verification through supplier documentation is especially important.

SS-31 peptide should be sourced and handled as a research-use compound, with purchase restricted to qualified professionals operating within their local regulatory framework. Those reviewing wholesale options should confirm COA availability and chain-of-custody documentation before placing an order. When buying SS-31 online, practitioners should also check for wholesale buying options that include batch-level purity and stability documentation appropriate for research-grade sourcing. Medical Spa Rx’s professional support team offers sourcing guidance and documentation support for licensed professionals evaluating qualified suppliers. Contact Medical Spa Rx’s professional support team directly for directions on verified sourcing.

FAQs

1. What is the SS-31 peptide, and what is it used for?

SS-31 peptide is a synthetic tetrapeptide, also known as Elamipretide or MTP-131, that selectively concentrates in the inner mitochondrial membrane and binds cardiolipin to stabilize electron transport chain complexes. It is studied for mitochondrial dysfunction, oxidative stress, exercise tolerance, cardiac and skeletal muscle protection, and renal injury, with the strongest human evidence in mitochondrial disease populations.[1],[2] As of June 2026, it is FDA-approved only for Barth syndrome under the Forzinity brand.[5]

2. What does the SS-31 peptide do?

SS-31 concentrates at approximately 1,000 times plasma concentration in the inner mitochondrial membrane, stabilizes ETC complexes through cardiolipin binding, reduces mitochondrial reactive oxygen species, prevents cytochrome c release, and preserves mitochondrial membrane potential. Its mechanism is best described as upstream structural membrane protection rather than metabolic signaling activation.

3. What is the SS-31 dosage?

Published clinical IV studies used approximately 0.005 to 0.25 mg/kg/h over 4 hours in investigational settings.[2],[4] The FDA-approved Barth syndrome protocol uses once-daily subcutaneous dosing, including 40 mg regimens.[5] Outside approved use, subcutaneous dosing should be described as practitioner-reported or research-extrapolated, not as a universally validated human protocol.

4. What are the SS-31 peptide benefits?

Exercise tolerance in primary mitochondrial myopathy has the most human trial data, though results are mixed: the 2017 dose-escalation trial showed a numerical but non-significant improvement in the 6MWT [2], and MMPOWER-3 did not meet its primary endpoint in the overall population.[1] Cardiac applications also show mixed outcomes across trials.[3],[4] Skeletal muscle and renal protective effects are primarily preclinical. All benefit claims require explicit evidence-tier qualification.

5. Is SS-31 FDA approved — what is its legal status?

As of June 2026, elamipretide is FDA-approved only as Forzinity for Barth syndrome, following accelerated approval granted on September 19, 2025.[5] For primary mitochondrial myopathy, HFpEF, renal indications, and longevity protocols, SS-31 remains investigational or off-label. Practitioners should maintain explicit on-label versus off-label distinctions. SS-31 is not currently on the WADA Prohibited List as of June 2026, though athletes should verify status independently.

6. How does SS-31 compare to MOTS-c and NAD?

SS-31 provides upstream structural cardiolipin-binding membrane protection and limits mROS at the source.[1],[2] MOTS-C activates AMPK-dependent nuclear signaling for metabolic aging and exercise adaptation. NAD replenishes the coenzyme substrate for sirtuin and PARP-mediated repair and mitochondrial biogenesis. All three target mitochondrial aging biology at different levels, with complementary rather than overlapping mechanisms, and a rational stacking case in comprehensive longevity protocols.

Sources

1. Karaa A, Bertini E, Carelli V, et al. Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial. Neurology. 2023;101(3):e238-e252. doi:1212/WNL.0000000000207402
2. Karaa A, Haas R, Goldstein A, Vockley J, Weaver WD, Cohen BH. Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy. Neurology. 2018;90(14):e1212-e1221. doi:10.1212/WNL.0000000000005255
3. Butler J, Khan MS, Anker SD, et al. Effects of Elamipretide on Left Ventricular Function in Patients With Heart Failure With Reduced Ejection Fraction: The PROGRESS-HF Phase 2 Trial. J Card Fail. 2020;26(5):429-437. doi:10.1016/j.cardfail.2020.02.001
4. Daubert MA, Yow E, Dunn G, et al. Novel Mitochondria-Targeting Peptide in Heart Failure Treatment: A Randomized, Placebo-Controlled Trial of Elamipretide. Circ Heart Fail. 2017;10(12):e004389. doi:10.1161/CIRCHEARTFAILURE.117.004389
5. S. Food and Drug Administration. FDA grants accelerated approval to first treatment for Barth syndrome. FDA.gov. Published September 19, 2025. https://www.fda.gov/news-events/press-announcements/fda-grants-accelerated-approval-first-treatment-barth-syndrome

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