SS-31 Protocol: Elamipretide Doses Used in Clinical Trials

Across several published human studies, a commonly investigated SS-31 (elamipretide) regimen was 40 mg given by subcutaneous injection once daily. This regimen was used in trials involving Barth syndrome, primary mitochondrial myopathy and heart failure. It is also the FDA-labeled dose of Forzinity for eligible patients with Barth syndrome, subject to the label's dose adjustments. These studies do not establish a general-use SS-31 protocol. Elamipretide has not been approved for general energy, longevity or athletic performance, and no published clinical trial identified in the research reviewed here has evaluated SS-31 combined with MOTS-c.

Key takeaways

• The commonly studied regimen: 40 mg subcutaneous elamipretide once daily in several clinical programs, ranging from 4-week studies to a 168-week open-label extension. Other trials investigated different doses and intravenous administration.
• The approved regimen: The Forzinity label sets 40 mg once daily for Barth syndrome patients weighing at least 30 kg, with 20 mg once daily for adults with severe kidney impairment who are not on dialysis.
• Online SS-31 protocols are not trial regimens: Community-reported lower doses, cycles and on/off schedules were not tested in the trials summarized here.
• SS-31 before MOTS-c: No trial has studied the two peptides together or in sequence. An "SS-31 first" order is a hypothetical research-design framework, not a validated sequence.

What is SS-31?

SS-31 is a four-amino-acid peptide (D-Arg-Dmt-Lys-Phe-NH2) that targets the inner membrane of mitochondria, the structures that produce most of a cell's energy. Its drug name is elamipretide, and it has also been called MTP-131 and Bendavia. SS-31 binds cardiolipin, a fat molecule in the inner mitochondrial membrane that helps hold the energy-producing machinery together. Stealth BioTherapeutics developed elamipretide and markets the approved version as Forzinity. For background on how SS-31 compares with other mitochondrial compounds, see our guide to peptides for mitochondria.

What SS-31 protocol did clinical trials use?

Several major elamipretide clinical programs used 40 mg injected subcutaneously once a day. Early trials tested intravenous (IV) infusions measured by body weight, and one phase 3 trial used 60 mg daily. The table lists the regimens from published and registered studies:

Trial	Population	Regimen	Duration	Main result
TAZPOWER (Thompson et al., 2021)	12 people with Barth syndrome	40 mg subcutaneous once daily vs placebo, crossover	12 weeks per arm, 4-week washout	Primary endpoints not met in the randomized part
TAZPOWER extension (Thompson et al., 2024)	10 people with Barth syndrome; 8 reached week 168	40 mg subcutaneous once daily, open label	168 weeks	6-minute walk distance improved from extension baseline (uncontrolled, open-label finding)
MMPOWER (Karaa et al., 2018)	36 adults with primary mitochondrial myopathy	IV 0.01, 0.1 or 0.25 mg/kg/hour for 2 hours daily	5 days	Dose-dependent increase in 6-minute walk distance
MMPOWER-2 (Karaa et al., 2020)	30 adults with primary mitochondrial myopathy	40 mg subcutaneous once daily vs placebo, crossover	4 weeks per arm, 4-week washout	Walk distance difference not significant; fatigue scores improved
MMPOWER-3 (Karaa et al., 2023)	218 adults with primary mitochondrial myopathy	40 mg subcutaneous once daily vs placebo	24 weeks	Did not meet primary endpoints; well tolerated
PROGRESS-HF (Butler et al., 2020)	71 adults with heart failure with reduced ejection fraction	4 mg or 40 mg subcutaneous once daily vs placebo	28 days	No change in heart-function measures vs placebo
Single-infusion heart failure study (Daubert et al., 2017)	36 adults with heart failure with reduced ejection fraction	One 4-hour IV infusion at 0.005, 0.05 or 0.25 mg/kg/hour	Single dose	No serious adverse events
NuPOWER (NCT05162768)	Primary mitochondrial myopathy from nuclear DNA mutations	60 mg subcutaneous once daily vs placebo	48 weeks	Completed; results not summarized here

Two patterns stand out. First, the trial protocols did not use cycling: participants took the same dose every day for the whole study period, and the washouts in crossover trials existed to compare elamipretide with placebo, not as rest periods. Second, a protocol does not make a result: several large trials using this exact regimen missed their primary goals.

What does the FDA label say about elamipretide dosing?

The Forzinity prescribing information sets 40 mg subcutaneously once daily for patients with Barth syndrome who weigh at least 30 kg. FDA granted accelerated approval in September 2025 based on improved knee-extensor muscle strength, and continued approval may depend on a confirmatory trial. Other label details include:

• Kidney function: Adults with an estimated glomerular filtration rate (eGFR) below 30 mL/minute who are not on dialysis get 20 mg once daily. The label gives no dose for adults on dialysis. The label also does not establish a dosing regimen for pediatric patients weighing at least 30 kg who have kidney impairment.
• Missed dose: Skip it and take the next dose at the usual time; do not double up.
• Product form: 280 mg in 3.5 mL (80 mg/mL) single-patient vials containing benzyl alcohol; not for intravenous use or for newborns.
• How the body handles it: After subcutaneous administration, elamipretide reaches peak blood concentrations in about 0.5 to 1 hour. In patients with normal kidney function, about 100% of the administered dose was recovered in urine within 48 hours as elamipretide or its metabolites. These pharmacokinetic findings describe drug handling; they do not, by themselves, establish the clinical dosing interval.

The label applies to one rare genetic disease. It does not support a protocol for any other use. For the full regulatory history, read our elamipretide FDA approval status guide.

How do online SS-31 protocols differ from the trials?

Online discussions of SS-31 sometimes describe lower doses, intermittent schedules, treatment cycles and combinations with other peptides. These are community-reported or commercially promoted approaches, not established clinical regimens. The published and registered elamipretide studies reviewed here do not validate those particular schedules. Their effectiveness, appropriate duration and safety cannot be inferred from trials involving different formulations, populations or dosing regimens.

Research-grade SS-31 is also a different product from Forzinity. A vial sold "for research use only" has not been reviewed by FDA for identity, purity, sterility or dose accuracy, even when the label names the same peptide. A recent sports-medicine review grouped SS-31 with other peptides sold directly to consumers and noted that rigorous human safety data for gray-market use are scarce (Mendias and Awan, Sports Medicine, 2026).

Should SS-31 come before MOTS-c?

There is no established clinical protocol requiring SS-31 to be used before, after or alongside MOTS-c. As of November 6, 2026, the literature search conducted for this article identified no clinical trial directly evaluating the two peptides together or in sequence.

The "SS-31 first, then MOTS-c" approach described in our mitochondrial peptides guide is a hypothetical research-design framework, not a clinically validated treatment sequence. Studying one intervention at a time may simplify attribution of observed effects, but it does not establish that SS-31 should come first, that the sequence improves mitochondrial function, or that either intervention is appropriate outside its studied setting.

The two peptides also work differently and carry very different evidence:

	SS-31 (elamipretide)	MOTS-c
What it is	Synthetic 4-amino-acid peptide that binds cardiolipin	16-amino-acid peptide encoded in mitochondrial DNA, studied as a metabolic signal
Human trials	Phase 2 and phase 3 trials, mostly 40 mg daily	No published efficacy trials; an analog called CB4211 had a phase 1a/1b study (NCT03998514)
FDA status	Approved as Forzinity for Barth syndrome only	Not FDA approved
2026 compounding policy	Elamipretide is not included in the six-substance interim policy. Forzinity is separately FDA-approved for its specified Barth syndrome indication.	Covered by the October 2026 HHS interim enforcement-discretion policy for certain patient-specific prescriptions compounded under Section 503A, subject to specified conditions. This does not constitute FDA approval.

For MOTS-c specifics, see our MOTS-c dosage chart, which separates research conventions from tested doses, and our MOTS-c clinical trials status update.

Can you take SS-31 and MOTS-c together?

There is no clinical data on taking SS-31 and MOTS-c together. Neither safety nor interactions have been studied for the combination, and MOTS-c has no established human dose. Any "SS-31 and MOTS-c protocol" posted online is therefore untested in people.

Is SS-31 safe?

In clinical trials, elamipretide at 40 mg daily was generally well tolerated, and the most common side effects were injection-site reactions. In the Barth syndrome crossover study on the Forzinity label, all 12 patients had injection-site redness while on elamipretide, and 9 of 12 had injection-site pain. The label also reports frequent increases in eosinophil counts (a type of white blood cell) during treatment lasting 30 days or longer. Counts generally peaked around 90 days after initial exposure and returned to baseline after 6 to 12 months of continued exposure or following discontinuation. It also warns about hypersensitivity reactions, including serious allergic reactions that needed emergency treatment, which can appear within minutes or months of starting. These safety findings apply to the pharmaceutical product in studied patients. They do not establish the safety of research-grade vials or of off-label schedules.

Seek emergency care for signs of a severe allergic reaction, such as trouble breathing or swelling of the face, lips or throat. Problems with a medicine can be reported to FDA MedWatch.

What is happening with SS-31 research in 2026?

Elamipretide research continues in 2026 across several conditions. These studies use daily subcutaneous dosing:

• 4TAZPower (NCT07531251): a placebo-controlled phase 3b/4 trial in Barth syndrome that began in July 2026 and is recruiting.
• ReNEW (NCT06373731): a phase 3 trial of 40 mg daily for 96 weeks in dry age-related macular degeneration.
• Healthy aging pilot (NCT07275424): a 4-week open-label safety study of daily elamipretide in adults aged 65 to 80.

Until these trials report results, the healthy-aging and eye-disease uses remain unproven.

Is research-grade SS-31 the same as Forzinity?

No. Forzinity is an FDA-approved prescription product for eligible patients with Barth syndrome and is obtained through an appropriate clinical care pathway. SS-31 products advertised for laboratory research are not equivalent to FDA-approved Forzinity and should not be treated as interchangeable medicines. A research-use-only label does not establish pharmaceutical-grade manufacturing, sterility or suitability for human injection.

Frequently asked questions

About this article: This guide reports regimens used in clinical research and on the FDA label. It is educational, not medical advice, and not a recommendation to use SS-31 or any peptide. PeptideStack is an affiliate publisher. The Peptide Partners card on this page is a paid referral offer and is separate from the research information. Commercial disclosure: Research-use SS-31 offers are listed separately on our SS-31 coupon code page. These products are not Forzinity, have not been FDA-approved for human use, and should not be treated as medicines for self-administration. Talk to a licensed clinician about any treatment decision.