Short answer: Both are linked to mitochondria, but their evidence is far apart. SS-31 (elamipretide) is FDA approved as Forzinity, under accelerated approval, to improve muscle strength in Barth syndrome.1 MOTS-c is a 16-amino-acid peptide encoded in mitochondrial DNA; its treatment data come from mice.2 We found no published controlled trials giving MOTS-c to people.
| MOTS-c | SS-31 (elamipretide, Forzinity) | |
|---|---|---|
| What it is | 16-amino-acid peptide encoded in the mitochondrial 12S rRNA gene2 | Tetrapeptide D-Arg-2,6-dimethyl-Tyr-Lys-Phe-NH21 |
| How it is thought to work | Acts mainly on muscle, activating AMPK (mouse and cell work)2 | Binds cardiolipin in the inner mitochondrial membrane1 |
| Approval status | Not approved | FDA approved 2025 (accelerated approval)1 |
| Approved use | None | Muscle strength in Barth syndrome, patients 30 kg and over1 |
| Dose | No human dosing trials found | Label: 40 mg under the skin once daily; lower dose in severe kidney impairment1 |
| Time to peak (Tmax) | No human data | 0.5 to 1 hour under the skin; bioavailability about 92%1 |
| Human evidence | Mostly measurements of natural blood levels, e.g. after exercise3 | 12-patient crossover trial plus a long open-label extension14 |
| FDA compounding / review | Nominated but withdrawn; reviewed by FDA advisory committee July 2026 (obesity, osteoporosis)56 | Approved drug |
Forzinity is approved under accelerated approval, based on knee muscle strength, an intermediate measure; continued approval may depend on a confirmatory trial.1 In its 12-week randomized crossover trial in 12 patients, it did not beat placebo on the main outcomes (6-minute walk and fatigue score), and strength did not rise in that phase. Strength gains appeared in the open-label extension, where 8 patients continued to week 168.14 The most common side effects were injection-site reactions, and it contains benzyl alcohol, so it is not for newborns.1
MOTS-c was described in 2015 as a peptide encoded in mitochondrial DNA. In mice, treatment prevented diet-induced obesity and age-related insulin resistance.2 Human work has mostly measured the body's own MOTS-c levels; a 2026 systematic review of exercise studies called the human evidence limited.3 FDA lists MOTS-c among compounding substances that were in Category 2 and then withdrawn, saying it lacks safety information, and its advisory committee reviewed it in July 2026.56 These are study protocols, not personalized advice; confirm any dosing with your prescriber.