SS-31 (Elamipretide) Reconstitution Calculator
SS-31 has a well established human dose and a very narrow approval, and the two do not cover the same ground. As elamipretide, sold as Forzinity, it was granted US accelerated approval in September 2025 to improve muscle strength in adult and paediatric patients with Barth syndrome weighing at least 30 kg, the first disease-specific treatment approved for that ultra-rare X-linked disorder. That is the only approved indication. Everything else, including mitochondrial myopathy, heart failure, longevity and performance use, is investigational, and the pivotal phase 3 in primary mitochondrial myopathy missed both of its co-primary endpoints. The dose itself is unusually solid for a compound in this library: one subcutaneous figure, used across the whole clinical programme, published in the range below with the trials that used it. The calculator on this page converts a vial size and a mixing volume into mg/ml and U-100 syringe units, which is arithmetic about a vial rather than a dose.
Curated by Dosavy from published literature and regulator labels. Published 11 September 2026, last reviewed 11 September 2026. No clinician reviews this page.
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What the evidence says
| Experience | Route | Range | Frequency |
|---|---|---|---|
| Beginner | Subcutaneous | 40 mg[1][2][3][4]One range only: there is no titration schedule for elamipretide; 40 mg once daily subcutaneously is the fixed dose used across the entire clinical programme, not a step in a ladder. Exposure at this dose has been studied for 24 weeks in the phase 3 (MMPOWER-3), for 12+12 weeks in the randomised Barth syndrome crossover (TAZPOWER), and continuously to 168 weeks in the TAZPOWER open-label extension. A 4 mg/day arm was also studied for 28 days in heart failure and is not included in this range. | Once daily |
- BeginnerSubcutaneous
Once daily
One range only: there is no titration schedule for elamipretide; 40 mg once daily subcutaneously is the fixed dose used across the entire clinical programme, not a step in a ladder. Exposure at this dose has been studied for 24 weeks in the phase 3 (MMPOWER-3), for 12+12 weeks in the randomised Barth syndrome crossover (TAZPOWER), and continuously to 168 weeks in the TAZPOWER open-label extension. A 4 mg/day arm was also studied for 28 days in heart failure and is not included in this range.
Published ranges, reported as the literature states them and numbered to the sources at the foot of this page. Not a recommendation.
Elamipretide has an unusually strong human dosing record for a compound in this category (a phase 3, a phase 2/3 with a 168-week open-label extension, several phase 2 trials and an accelerated approval), and 40 mg once daily subcutaneously is the dose used consistently across the programme. Two other human routes exist and are deliberately not recorded as ranges. INTRAVENOUS: continuous infusions of 0.05-0.25 mg/kg/h were used in the acute cardiology and renal studies (EMBRACE STEMI at 0.05 mg/kg/h for 1 h, PMID 26586786; ascending-dose heart failure infusions to 0.25 mg/kg/h, PMID 29217757; renal artery stenosis at 0.05 mg/kg/h, PMID 28916603) and in a dose-escalation study in mitochondrial myopathy (PMID 29500292). These are weight-scaled infusion rates for acute in-hospital use and are not convertible into a fixed self-administered dose. TOPICAL OPHTHALMIC: a 1% solution was studied in Leber hereditary optic neuropathy (PMID 37923251), a concentration, not a mass dose, and not representable in this schema's units. A lower 4 mg/day subcutaneous arm was also studied in heart failure and, like the 40 mg arm, did not meet its endpoint (PMID 32068002); it is noted rather than used to widen the range, since 40 mg is the dose the entire mitochondrial-disease programme and the approval rest on. Note finally that the strength of the dosing evidence is not the strength of the efficacy evidence: the dose is well established, and the two largest trials of it were negative.
SS-31 (Elamipretide) at a glance
- Category
- Longevity
- Half-life
- Not established
- Routes
- Subcutaneous, Topical, Other
- Regulatory status
- Approved
- Also sold as
- Elamipretide, SS-31, ss 31, MTP-131, Bendavia, Forzinity
Mechanism
A water-soluble aromatic-cationic tetrapeptide that concentrates in the inner mitochondrial membrane and binds cardiolipin, the phospholipid that shapes the cristae and holds the electron transport chain complexes in productive association. Stabilising cardiolipin improves oxidative phosphorylation efficiency and reduces electron leak and reactive oxygen species production. The clinical rationale was proven first in Barth syndrome, where mutations in the TAZ gene leave up to 95% of cardiolipin structurally immature; elamipretide is the first disease-specific treatment approved for that disorder. In older adults a single dose measurably raised in-vivo skeletal muscle ATPmax relative to placebo, an effect that had disappeared by day 7 consistent with the peptide's short blood half-life.
Reconstitution
The approved elamipretide product is a pharmacy-dispensed injectable, not a compounding exercise. Research-chemical 'SS-31' is typically supplied as a lyophilised powder with no validated diluent, concentration or in-use stability period; reconstituting it does not reproduce the approved drug.
Storage
The approved product is dispensed by a pharmacy: follow its storage instructions. Material sold as 'SS-31' through research-chemical channels is not that product and carries no validated storage specification.
Frequency in practice
Once daily by subcutaneous injection in the trials supporting the approved use. Intravenous infusion was used in the acute cardiology and renal studies; a topical ophthalmic formulation is separate.
Regulatory
In September 2025 elamipretide (Forzinity) was granted US accelerated approval to improve muscle strength in adult and paediatric patients with Barth syndrome weighing at least 30 kg, the first disease-specific treatment approved for that ultra-rare X-linked disorder (PMID 41335372). That is the only approved indication. Phase 3 development continues in dry age-related macular degeneration and mitochondrial myopathies. Everything else (mitochondrial myopathy, heart failure, longevity or performance use) is investigational, and the peptide sold as 'SS-31' by research-chemical vendors is not the approved product.
What to know before anything else
The approval is narrow and conditional: Barth syndrome only, patients weighing at least 30 kg, granted under accelerated approval. Every other use is investigational, including all of the mitochondrial, longevity and performance uses the peptide is marketed for.
THE PIVOTAL PHASE 3 FAILED. MMPOWER-3 randomised 218 people with genetically confirmed primary mitochondrial myopathy to 40 mg/day subcutaneous elamipretide or placebo for 24 weeks and missed both co-primary endpoints: no difference in 6-minute walk distance (-3.2 m, 95% CI -18.7 to 12.3) and none in total fatigue score (PMID 37268435). Elamipretide is not an established treatment for fatigue or exercise capacity.
It also failed in heart failure. In PROGRESS-HF, neither 4 mg nor 40 mg daily for 28 days changed left ventricular end-systolic volume versus placebo in 71 patients with reduced ejection fraction (PMID 32068002).
Injection-site reactions are the most common adverse event with daily subcutaneous dosing, reported through 168 weeks of open-label extension (PMID 38602181).
Material sold as 'SS-31' outside a pharmacy is not Forzinity. Identity, purity, sterility and concentration are unverified, and none of the trial evidence below applies to it.
The evidence base is built almost entirely in rare genetic mitochondrial disease. Extrapolating from Barth syndrome or primary mitochondrial myopathy to healthy adults seeking an anti-ageing or performance effect is not supported by anything in the literature.
SS-31 (Elamipretide) questions
Is there an established human dose for SS-31?
Yes, and it is one of the better established doses on this site. A single once-daily subcutaneous figure runs through the entire elamipretide programme: a phase 3 in primary mitochondrial myopathy, a phase 2/3 randomised crossover in Barth syndrome, a 168-week open-label extension of that crossover, and the accelerated approval itself. There is no titration ladder. The figure is in the range table above, with each trial that used it named beside it.
How does elamipretide work?
It is a water-soluble aromatic-cationic tetrapeptide that concentrates in the inner mitochondrial membrane and binds cardiolipin, the phospholipid that shapes the cristae and holds the electron transport chain complexes in productive association. Stabilising cardiolipin improves oxidative phosphorylation efficiency and reduces electron leak and reactive oxygen species production. The clinical rationale was proven first in Barth syndrome, where mutations in the TAZ gene leave up to 95% of cardiolipin structurally immature, which is why the single approval sits in that disorder rather than in a general mitochondrial indication.
What did the elamipretide trials actually show?
Four published human studies carry the dose, and they point in two directions. MMPOWER-3, a 2023 phase 3 in Neurology, randomised 218 people with genetically confirmed primary mitochondrial myopathy to 24 weeks of elamipretide or placebo and missed both co-primary endpoints: no difference in 6-minute walk distance (-3.2 m, 95% CI -18.7 to 12.3) and none in total fatigue score. A 2020 randomised crossover in the same population found a change in the 6-minute walk test that was clinically meaningful but did not reach statistical significance. TAZPOWER, a 2021 phase 2/3 randomised crossover in 12 people with Barth syndrome, and its 2024 open-label extension running to 168 weeks, are where the reported improvement and the approval come from. Two further human routes exist and are deliberately not turned into ranges here: weight-scaled intravenous infusions used in acute in-hospital cardiology and renal studies, which do not convert into a fixed self-administered dose, and a topical ophthalmic solution studied in Leber hereditary optic neuropathy, which is a concentration rather than a mass.
What is Forzinity approved for?
Barth syndrome only, in adult and paediatric patients weighing at least 30 kg, to improve muscle strength, granted in September 2025 under accelerated approval. It is the first disease-specific treatment approved for that disorder. Phase 3 development continues separately in dry age-related macular degeneration and in mitochondrial myopathies, so both of those remain investigational rather than approved.
Does SS-31 do anything for ageing or athletic performance?
Nothing in the published literature supports that use. The one human signal pointing in that direction is narrow: in older adults a single dose measurably raised in-vivo skeletal muscle ATPmax relative to placebo, and the effect had disappeared by day 7, consistent with the peptide's short blood half-life. The evidence base is otherwise built almost entirely in rare genetic mitochondrial disease. Outside it, PROGRESS-HF found that neither of the two daily doses studied changed left ventricular end-systolic volume against placebo in 71 patients with heart failure with reduced ejection fraction. Extrapolating from Barth syndrome to a healthy adult seeking an anti-ageing or performance effect is not supported by anything here.
Is research-grade SS-31 powder the same as Forzinity?
No. The approved product is pharmacy-dispensed, and reconstituting a research powder does not reproduce it. Material sold as SS-31 outside a pharmacy has no validated diluent, no validated concentration and no in-use stability period; its identity, purity, sterility and strength are unverified; and none of the trial evidence on this page applies to it. It also carries no storage specification of its own, so handling claims printed on the vial rest on the supplier's word.
What are the side effects of daily subcutaneous elamipretide?
Injection-site reactions are the most common adverse event, and that comes from an unusually long exposure: patients in the TAZPOWER open-label extension continued daily subcutaneous dosing for up to 168 weeks, over which elamipretide was well tolerated. In the phase 3, treatment was also reported as well tolerated across 24 weeks in 218 people. Tolerability is the part of this programme that held up; efficacy outside Barth syndrome is the part that did not, and the strength of the dosing evidence here is not the strength of the efficacy evidence.
Every number above, and where it came from
4 sources, numbered where they are used. Each one links to the paper or the label itself, not to a summary of it.
- [1]Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial.
Neurology · 2023 · Phase 3 randomized, double-blind, placebo-controlled trial · n=218
- [2]A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome, a genetic disorder of mitochondrial cardiolipin metabolism.
Genetics in medicine · 2021 · Phase 2/3 randomized crossover trial with open-label extension · n=12
- [3]Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER.
Genetics in medicine · 2024 · Open-label extension of a randomized controlled trial
- [4]A randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy.
Journal of cachexia, sarcopenia and muscle · 2020 · Randomized crossover trial
The rest of the math
- Reconstitution calculatorThe full version of the tool above, with syringe barrel sizes and IU conversion.
- Vial longevityHow many doses a vial holds and the date it runs out.
- Cost per doseVial price against doses drawn, so two vial sizes can be compared honestly.
- Half-life and decayFirst-order clearance, time to steady state, and what remains at a given hour.
Same class as SS-31 (Elamipretide)
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