SS-31 Dosage Guide 2026: Clinical Trials vs Reported Use

The calculator

Five inputs, three outputs, no opinion in between: type the vial strength, the water, the syringe scale, the barrel size and whichever milligram figure you are checking, and the tool returns what that mix is worth per milliliter and per unit.

SS-31 dosage chart: the published figures, with route and population

One row per source, population printed beside the number: every injected SS-31 amount named in the fourteen sources at the foot of this page, with the route and the group each was given to alongside it, plus the one recruiting subcutaneous pilot that publishes no amount, kept in because the missing number is the point. Three kinds of record sit outside the chart and are described further down instead: the three topical ophthalmic studies, which dose a percentage solution into the eye rather than a milligram amount into tissue; the two oral studies, which are not injections; and three intravenous records that publish no milligram amount at all, two of them naming their arms only low, intermediate and high. There is no beginner row and no maintenance row, because no source publishes one.

Read the population column before the number: every subcutaneous figure below belongs to a disease trial except one, a ten-subject phase 1 that injected healthy volunteers to study injection site reactions rather than any benefit, and the biggest of the disease trials missed both of its primary endpoints. An amount that was studied is not the same thing as an amount that worked.

One molecule, four names: SS-31, elamipretide, MTP-131 and FORZINITY all point at the same tetrapeptide. The 2023 GeroScience paper by Pharaoh and colleagues pairs the first two in its own title, the 2015 registry record for the myopathy trial is filed under MTP-131, and the label carries the four-residue sequence that sits behind every one of those names.

The conversion this page does not perform: the per-kilogram figures above went in through a vein, and nothing on this page carries them across into a subcutaneous milligram amount. One source does compare the two routes, and it is worth reading for what it does and does not settle: the MMPOWER-2 paper says its subcutaneous formulation was chosen as "comparable with the highest dose studied in MMPOWER" and that "SC bioavailability was calculated (~90%), confirming the sameness of the two formulations". That is a statement about two formulations of one drug, not a factor anyone can apply to another amount.

The conversion this page does perform: milligrams into syringe units, further down. That one is division, and it holds for whatever figure goes into it and wherever the figure came from.

What dose does the FDA label specify for SS-31?

The number, and the population it belongs to: section 2.1 of the FORZINITY prescribing information reads that the recommended dosage in patients weighing at least 30kg is 40mg subcutaneously once daily, and that patients should receive it at the same time each day.

The single adjustment the label carries: Table 1 in section 2.2 is headed "Recommended Dosage in Adults with Renal Impairment". It keeps 40mg once daily at an eGFR of 30 mL per minute or above, and drops to 20mg once daily in adults below 30 who are not on dialysis. The label states outright that there is insufficient information to recommend a regimen for adults on dialysis, or for pediatric patients weighing 30kg or greater with renal impairment.

What the approved use actually covers: section 1 reads that FORZINITY "is indicated to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg". That sentence is the entire indication. Aging, mitochondrial fitness and athletic recovery appear nowhere in it.

And the approval is provisional: the same section records that it was granted under accelerated approval on an improvement in knee extensor muscle strength, an intermediate clinical endpoint, with continued approval contingent on verification in a confirmatory trial. That trial, SPIBA-401, was first posted to the registry on 15 April 2026 and started on 2 July 2026.

Where 40mg sits in the studied exposure range: section 12.3 reports that elamipretide exposure rises proportionally across a range of 2 to 80mg on daily subcutaneous injection with minimal accumulation, that absolute bioavailability by that route is approximately 92 percent, and that peak concentrations arrive between half an hour and one hour after the injection.

How often is SS-31 given, and how long does a course run?

Once a day, everywhere the record injects it repeatedly: the label, the two Barth syndrome papers, the subcutaneous myopathy trials and their open-label extension, the subcutaneous eye trials, the heart failure trials and the later subcutaneous trials at 60mg and in Friedreich ataxia all specify one dose per day. Most of the infusion studies gave a single dose instead, but not all of them: the acute heart failure trial infused for seven consecutive days, and so did a phase 1 in four renal-function cohorts that publishes no milligram amount. The only twice-daily schedule in the record is the topical ophthalmic one, shared by all three of the eye-drop studies, where the drug is a drop rather than an injection. Twice weekly, alternate days and five-on-two-off appear in none of them.

The durations that exist in the record: 7 days by infusion in acute heart failure, 28 days in the heart failure injection trial, 4 weeks per arm in MMPOWER-2, 12 weeks per arm in TAZPOWER, 24 weeks in MMPOWER-3 and in the first eye trial, 48 weeks in ReCLAIM-2 and in NuPOWER, 52 weeks in the Friedreich ataxia study, 96 weeks in the ReNEW phase 3 that has not reported, and 168 weeks of treatment in the Barth syndrome extension for 8 of the 10 subjects who entered, inside an extension period the label itself describes as 192 weeks.

No off period appears in the label: it sets no stop date and describes no break, and its only instruction about a gap is that a missed dose is skipped rather than doubled. Two trials did build in a gap, but as a crossover washout rather than a cycle: four weeks between the two periods in TAZPOWER, and four weeks between the two periods in MMPOWER-2. No trial protocol we read used a repeating on-and-off block of any kind.

Time of day, per the label: section 2.1 asks for the same time each day and names no hour, which is the whole of what the document settles on timing.

What a frequency without a matching dose is worth: in this case the record is unusually complete on both. The gap is not between how often and how much, it is between the population studied and the population reading about it.

Which route did the SS-31 trials use?

Subcutaneous on the label and in the trials behind it: section 2.3 directs the injection into the abdomen at least two inches from the navel, or into the outer thigh, with the site rotated daily. Section 12.3 reports comparable exposure from the thigh and from the abdomen.

Intravenous in the earlier work, and in one large heart failure trial: the 2018 dose-escalation trial ran three sequential cohorts of 12 adults with mitochondrial myopathy, 9 on drug and 3 on placebo in each, infusing elamipretide over two hours at 0.01, 0.1 or 0.25mg per kilogram per hour, and the 2021 study infused older adults for two hours at the highest of those three rates, with 19 on drug and 20 on placebo in its analysis. Eight further intravenous records sit in the registry, and a ninth was withdrawn before it enrolled anyone: five ascending rates in 40 healthy adults, the top rate again in 12 healthy volunteers alongside heparin and in 6 more around a single cigarette, 0.05mg per kilogram per hour around coronary angioplasty in 300 patients and around renal artery angioplasty in 16, single ascending infusions in 36 people with heart failure at amounts the record does not publish, once-daily one-hour infusions for seven consecutive days across four renal-function cohorts at amounts it also does not publish, and a flat 20mg once daily for seven days in 308 people hospitalized with heart failure. None of them is a subcutaneous milligram figure and none becomes one on this page.

Topical in the eye, in three small studies: three ophthalmic trials dosed a 1.0% or 3.0% elamipretide solution as drops twice a day, in diabetic macular edema, in Fuchs' corneal endothelial dystrophy and in Leber's hereditary optic neuropathy. Twice a day is the only schedule of its kind in the record, and the eye is the only place the drug is not injected or swallowed.

Oral, in two phase 1 studies that never reported: 30 healthy volunteers took a single 10, 50 or 100mg capsule in one, and 30 more took 10 or 50mg once daily for seven days in the other. Both are filed as completed and neither has posted a result, which is why the oral route sits outside the chart and outside every dosage discussion of this compound, including this one.

Why route sits underneath the number rather than beside it: what reaches the bloodstream from a vein over two hours and what reaches it from the abdomen over the same period are different quantities, and only the second one has a label behind it. What the trial documents record about sites and rotation, and what they leave out, sits on the injection-sites page.

Where does the 500mcg SS-31 figure come from?

Not from any source at the bottom of this page: the smallest injected amount named anywhere in them is the 1.4mg a day the lowest MMPOWER cohort averaged, and that is a per-kilogram infusion rate in a disease population rather than a fixed injected amount. The smallest subcutaneous amount measured against an outcome in these sources is the 4mg arm of one 28-day heart failure trial, eight times the circulating figure. Section 12.3 of the label puts the bottom of its studied exposure range at 2mg, but a pharmacokinetic range is not a tested effect.

No figure on this page is offered as yours, and the two figures in play differ by a factor of eighty.

What that gap is and is not: 40mg against 500mcg is not a rounding disagreement and not a units slip between milligrams and micrograms. It is two different claims about what the compound does, and only one of them has been through a controlled trial at the amount it names.

Does SS-31 need reconstitution?

The approved product does not: section 3 of the label describes an injection of 280mg in 3.5mL, which works out at 80mg per mL, supplied as a sterile aqueous solution in single-patient-use vials. Section 11 calls it ready to use and records that each 0.5mL dose holds 40mg of elamipretide alongside 10mg of benzyl alcohol as a preservative.

Which means the water tables online are not describing the approved product: nothing that arrives premixed at a fixed strength needs a water volume chosen for it. What is in the vial those tables do describe is not something we can document, and what a lyophilized peptide is covers why a dried powder gets sold that way and what the drying step does and does not settle about the contents.

The label's own storage line: section 16.2 holds vials at 2 to 8 degrees Celsius, permits an opened vial at room temperature between 20 and 25 degrees, and discards it 8 days after first opening.

Why the last row matters more than the six above it: at 80mg per mL the labeled 40mg is 0.5mL, which reads as 50 units on a U-100 barrel. At the 5mg per mL of the second row, the same 40mg would be 8mL, which is eight full 1mL barrels of liquid and, because a 10mg vial holds 10mg in total, the entire contents of four such vials rather than one. The approved presentation is concentrated because the approved amount is large.

The general form of the division: vial milligrams over water milliliters gives the concentration, and the amount over that concentration gives the volume. Concentration versus dose works it through for any vial, and the reconstitution calculator runs it without the longhand.

How many units is 500mcg of SS-31?

Three ordinary mixes, three different answers: from a 10mg vial in 2mL, 500mcg is 10 units on a U-100 syringe. The same vial in 1mL puts it on 5 units. A 50mg vial in 2mL puts it on 2 units.

Why the question has no answer without the mix: the amount is a mass and the syringe measures a volume, so the number joining them is the concentration, and the concentration was fixed by whoever chose the water. A unit is a volume, not a dose is the whole of that idea.

The barrel scale sits on top of that, not instead of it: every count above is a U-100 count. Pulled on the other scale in circulation, the same unit number carries two and a half times the volume, and that multiplier applies after whichever row of the table above is in play. The two scales have their own page.

The labeled amount on the labeled product, for comparison: 40mg out of an 80mg per mL solution is 0.5mL, or 50 units on a U-100 barrel, and the 20mg renal-impairment figure is 0.25mL, or 25 units. Both are printed strengths rather than mixes, so neither one moves.

What is not known yet about SS-31?

Approved, but for one genetic disease and on a provisional basis: the approval of 19 September 2025 covers Barth syndrome and nothing else, and the confirmatory trial that accelerated approval calls for only began recruiting in July 2026, with 48 subjects planned and a primary completion date in 2029.

The healthy-population record is thin and mostly unreported: the registry flags seven elamipretide studies as enrolling healthy volunteers, by infusion, by mouth and in one recruiting subcutaneous pilot, and not one of the seven has posted a result. The one dose-ranging study among them ran in 2010, gave five ascending infusion rates to 40 people, and posted nothing. Two studies the registry does not flag that way did report: the 2021 trial, whose paper calls its subjects healthy older adults, gave a single two-hour infusion, and a ten-person phase 1 gave a fixed 60mg under the skin on six occasions and measured injection site reactions and blood levels rather than function. That second one is the only subcutaneous injection into healthy subjects we found reported anywhere. A phase 2a open-label pilot of daily subcutaneous elamipretide in adults aged 65 to 80 began recruiting in November 2025 with 30 subjects planned and four weeks of injections, and its registry record publishes the vial strength and no milligram amount.

Outside Barth syndrome the efficacy record is mostly negative: the myopathy phase 3, the heart failure phase 2 and the geographic atrophy phase 2 all missed their primary endpoints on the same 40mg daily schedule. A phase 3 in dry macular degeneration, ReNEW, randomized 313 subjects 2 to 1 to 40mg daily or placebo for 96 weeks, so roughly 209 of them are on drug, and it is not due to complete before 2027.

Three holes, and none of them is small:

• No subcutaneous dose-ranging study in healthy adults. The label puts the studied exposure range at 2 to 80mg, the one dose-ranging study in healthy adults was intravenous and posted no results, and the single subcutaneous study in healthy subjects used one fixed amount and looked at tolerability rather than effect.
• Thin multi-year data, and none of it controlled. Outside Barth syndrome the longest posted record is an open-label extension in primary mitochondrial disease, 28 subjects on 40mg a day with outcomes posted out to week 160 and no comparison group, and one topical eye study ran 52 masked weeks before an open-label stretch to that same week 160. Of the randomized trials above, the longest is the 96 weeks of ReNEW, and it has not reported.
• No evidence for the circulating amount. A 500mcg injection appears in no trial in the list below.

One gap sits underneath the other three: the approved product is a solution whose strength is printed on a label FDA reviewed, and any other vial carries a number we have no way to check.

Every unit count on this page assumes the vial holds what the vial says, and the only elamipretide presentation FDA has approved is the one section 16.1 of the FORZINITY label describes, a 280mg in 3.5mL vial at a fixed 80mg per mL under a single NDC.

How this page is sourced

Read off the label and the papers themselves: every figure in the tables above was taken from the document cited beside it, never from another site's summary of that document. One figure on this page has no document behind it, the 500mcg that circulates for this compound, and that is exactly why it is reported as circulation and never as a chart row.

Fourteen sources, one of them an approved drug label: eleven peer-reviewed papers, one structured product label, one regulator trial snapshot, and twenty-three registry records grouped into a single entry. Open them yourself: every figure printed above is meant to be checkable against the document it came from.

What we could not settle: the two recruiting studies publish a vial strength and no milligram amount, so this page reports them that way rather than assuming they run at the labeled figure. Several completed trials, including the 60mg one and the 20mg intravenous one, have posted no results, so their amounts appear here without an outcome beside them, and two intravenous records publish no amount at all. The 500mcg carries no document, which is why it sits in its own section and never in the trial rows.

Where the rules behind that live: how we pick a source, and what has to be true before a figure is printed at all, is set out on the methodology page. Corrections are logged there before they reach a page like this one.

Last reviewed: 2 August 2026.

1. 1

   FORZINITY (elamipretide) injection, for subcutaneous use. Prescribing information, Stealth Biotherapeutics Inc. That is the title as printed in the label's own Highlights section; the DailyMed landing page displays it as "FORZINITY- elamipretide hydrochloride injection", naming the salt that section 11 describes. Sections 1 (indication and accelerated approval), 2.1 and 2.2 (recommended dosage and renal adjustment), 2.3 (administration), 3 (280 mg/3.5 mL, 80 mg/mL), 5.1 (benzyl alcohol), 6.1 (adverse reactions, and the 168 and 192 week exposure counts), 11 (sequence and 0.5 mL dose composition), 12.1 (cardiolipin binder), 12.3 (exposure range and bioavailability), 14 (the "192-week, open-label, single-arm extension period"), 16.1 (the single presentation and NDC) and 16.2 (storage). Structured product label read from the DailyMed v2 API on 2 August 2026, HTTP 200. DailyMed set id 146bf34c-76f2-48db-ac07-fb29cce2cd75.

2. 2

   U.S. Food and Drug Administration. Drug Trials Snapshots: FORZINITY. Source for the approval date of 19 September 2025, the once-daily subcutaneous administration, the 12-patient single-site trial population, and the description of SPIBA-201 Part 2 as "a 192-week, single-arm, open-label extension" through which eight of the ten entrants "participated through 168 weeks". Retrieved 2 August 2026, HTTP 200. fda.gov snapshot.

3. 3

   Reid Thompson W, Hornby B, Manuel R, et al. 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. Genet Med. 2021;23(3):471-478. doi:10.1038/s41436-020-01006-8. PMID 33077895.

4. 4

   Thompson WR, Manuel R, Abbruscato A, et al. Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER. Genet Med. 2024;26(7):101138. doi:10.1016/j.gim.2024.101138. PMID 38602181.

5. 5

   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:10.1212/WNL.0000000000207402. PMID 37268435.

6. 6

   Karaa A, Haas R, Goldstein A, Vockley J, Cohen BH. A randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy. J Cachexia Sarcopenia Muscle. 2020;11(4):909-918. doi:10.1002/jcsm.12559. PMID 32096613.

7. 7

   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. PMID 29500292.

8. 8

   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. PMID 32068002.

9. 9

   Mettu PS, Allingham MJ, Cousins SW. Phase 1 clinical trial of elamipretide in dry age-related macular degeneration and noncentral geographic atrophy: ReCLAIM NCGA study. Ophthalmol Sci. 2022;2(1):100086. doi:10.1016/j.xops.2021.100086. PMID 36246181.

10. 10

    Ehlers JP, Hu A, Boyer D, et al. ReCLAIM-2: a randomized phase II clinical trial evaluating elamipretide in age-related macular degeneration, geographic atrophy growth, visual function, and ellipsoid zone preservation. Ophthalmol Sci. 2025;5(1):100628. doi:10.1016/j.xops.2024.100628. PMID 39605874.

11. 11

    Roshanravan B, Liu SZ, Ali AS, et al. In vivo mitochondrial ATP production is improved in older adult skeletal muscle after a single dose of elamipretide in a randomized trial. PLoS One. 2021;16(7):e0253849. doi:10.1371/journal.pone.0253849. PMID 34264994.

12. 12

    Pharaoh G, Kamat V, Kannan S, et al. The mitochondrially targeted peptide elamipretide (SS-31) improves ADP sensitivity in aged mitochondria by increasing uptake through the adenine nucleotide translocator (ANT). GeroScience. 2023;45(6):3529-3548. Cited for the title's own pairing of the two names for one molecule. doi:10.1007/s11357-023-00861-y. PMID 37462785.

13. 13

    Sullivan A, Bergheanu SC, Kropp LE, Zhang L, Beck LA, McNeil B, Abbruscato A. Interventions with potential to mitigate injection site reactions following subcutaneous elamipretide administration: a phase 1, crossover study. Arch Microbiol Immunol. 2023;7(4). Cited for the only subcutaneous administration to healthy subjects we found reported anywhere: 60 mg to 10 subjects on six separate occasions, measuring injection site reactions, pharmacokinetics and safety rather than any efficacy outcome. What resolved and what did not, because the difference matters here: the journal record resolved through Crossref, HTTP 200, with the authors, title, journal, year, volume and issue above; the publisher's own article page returned a Cloudflare block to us and its body was never read; the design and outcomes quoted on this page were read from the Europe PMC record of the same study's preprint, HTTP 200, which is a preprint and is labelled as one here for that reason. It is the weakest source on this list and it is the only one that answers the question it is cited for. doi:10.26502/ami.936500128. Europe PMC preprint record PPR690651.

14. 14

    ClinicalTrials.gov registry records, read from the v2 API on 2 and 3 August 2026, each returning HTTP 200 and a substantive record. NCT07275424, the phase 2a open-label pilot of daily subcutaneous elamipretide in older adults, recruiting, 30 planned, no milligram value published. NCT07531251, the SPIBA-401 post-marketing confirmatory trial in Barth syndrome, recruiting from 2 July 2026, 48 planned, primary completion estimated 2029. NCT06373731, the ReNEW phase 3 in dry macular degeneration, 313 enrolled and randomized 2 to 1 to 40mg subcutaneously daily or placebo for 96 weeks, active and not recruiting. NCT02367014, completed, whose title reads "Safety, Tolerability, and Efficacy of MTP-131 for the Treatment of Mitochondrial Myopathy", cited for the older name, for the posted participant flow showing 9 subjects started in each of the low, intermediate, high and placebo arms, and for the posted 6-minute walk change of 13.5 meters in the low-rate arm against 20.4 in placebo. NCT01115920, completed, the first-in-human study, 40 healthy adults across five cohorts of 8 at 0.010, 0.025, 0.050, 0.100 and 0.250 mg/kg/hr as a single 4-hour intravenous infusion, 6 on drug and 2 on placebo per cohort, no results posted. NCT01572909, EMBRACE-STEMI, completed, 300 randomized with posted flow of 152 on drug and 148 on placebo, intravenous at 0.05 mg/kg/hr around angioplasty. NCT02914665, completed, 308 randomized, "20 mg elamipretide administered intravenously once daily for 7 consecutive days" in patients hospitalized with congestion due to heart failure, no results posted. NCT05162768, NuPOWER, completed phase 3, 102 randomized, "60 mg of elamipretide administered as once daily 0.75 mL subcutaneous injections for 48 weeks", no results posted. NCT05168774, ELViS-FA, completed, daily subcutaneous elamipretide at 20 to 30mg and at 40 to 60mg for 52 weeks in Friedreich ataxia, posted flow showing 8 started in each band. NCT02314299, NCT02653391 and NCT02693119, all three completed, the topical ophthalmic studies in diabetic macular edema, Fuchs' corneal endothelial dystrophy and Leber's hereditary optic neuropathy, dosing a 1.0% or 3.0% solution as drops twice a day, cited for the only twice-daily schedule in the record. The LHON record carries posted results through a masked period and an open-label extension, its outcome tables running to a week 160 end-of-treatment visit. NCT02245620, MOTION, completed, the registry record behind the 2021 older-adult infusion paper, cited for the posted participant flow of 20 elamipretide and 21 placebo started against 19 and 20 completed. NCT02814097, completed, 46 with heart failure and preserved ejection fraction, "Subcutaneous injection of 40 mg elamipretide once daily for 28 consecutive days", no results posted. NCT02976038, terminated after the registration trial missed its primary endpoints, the open-label extension in primary mitochondrial disease, 28 started on "40 mg, subcutaneous injections (in the abdomen) daily" for up to 260 weeks, cited for posted outcome tables at weeks 104, 130, 156 and an end of trial at week 160, which is the multi-year record outside Barth syndrome. NCT01754818 and NCT01786915, both completed, the two oral phase 1 studies in 30 healthy volunteers each, a single 10, 50 or 100mg capsule in the first and 10 or 50mg once daily for seven days in the second, neither with results posted, cited because they are the reason the eye is not the only route that is not an injection. NCT01513200 and NCT01518985, both completed, 12 and 6 healthy volunteers at "0.25mg/kg/hr" intravenously for 4 hours, alongside unfractionated heparin and around a single cigarette respectively, no results posted. NCT01755858, terminated at 16 subjects, intravenous "0.05 mg/kg/hr" around renal artery angioplasty. NCT02388464, completed, single ascending intravenous infusions over 4 hours in 36 subjects with heart failure, arms named only low, intermediate and high with no milligram amount published. NCT02436447, completed, 23 subjects in four renal-function cohorts including a normal-function one, "administered as once-daily 1- hour intravenous infusion for 7 consecutive days", again with no milligram amount published, cited as the repeat-dose infusion that the record's single-dose infusions are not. NCT02388529, withdrawn with 0 enrolled, the multiple ascending dose intravenous study in heart failure, cited only as the ninth intravenous record and as a study that never ran.