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SS-20

Also known as

SBT-20 · SBT-020 · SBT20 · SBT 20 · Phe-D-Arg-Phe-Lys-NH2 · H-Phe-D-Arg-Phe-Lys-NH2 · Szeto-Schiller peptide SS-20 · Szeto-Schiller peptide 20 · SS20 · SS 20

Community talk. May be wrong. Not medical advice. Not a protocol. Not for human or animal use.

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Peptide Niche talk Systemic SubQ Mitochondrial & metabolic peptides

Systemic with preferential concentration at the inner mitochondrial membrane after parenteral exposure; far less community volume than SS-31/elamipretide.

What people say SS-20, developed clinically as SBT-020, is a Szeto-Schiller mitochondrial-targeting tetrapeptide distinct from SS-31. It lacks SS-31's Dmt residue; one early-Huntington's human program established short SC safety and PK but found no overall mitochondrial pharmacodynamic improvement. Doses people talk about
Early-HD multiple-dose phase5, 15, or 25 mg SubQ once daily for 7 days

Six participants per cohort received active SBT-020 and two placebo while safety and PK were assessed.

Early-HD longer phase25 mg SubQ once daily for 28 days

Re-randomized active-versus-placebo phase; it showed no overall mitochondrial or clinical-function separation.

Healthy-volunteer background5, 10, 20, or 30 mg SubQ

Earlier single- and multiple-ascending-dose assessments informed later patient-dose selection and reported dose-related local reactions.

The HD and healthy-volunteer rows are distinct study populations and designs. They do not establish an approved indication, long-term consumer cycle or self-administered escalation plan.

Half-life & effect duration

Half-life in the body
  • Under-the-skin injection · day-7 studyAbout 3.1–4.1 hours
Felt duration people report
  • Study observationsFrequent mild local reactions
  • Personal felt durationNo consistent SS-20-specific timeline reported
Timing context & sources
How it may feel There is no well-supported SS-20 consumer feel timeline. In the early-Huntington's study, mild injection-site reactions dominated treatment-emergent events, while 7- and 28-day dosing produced no overall mitochondrial or clinical-function separation; public forum discussion located here repeated literature rather than firsthand SS-20 use.
Cycles people discuss No dense consumer cycle consensus exists. The documented human program used 7 daily SubQ doses, at least a one-month washout, then a 28-day daily phase; borrowed SS-31 calendars are not SS-20 evidence. Timing The retained clinical notes describe protocol-timed dosing around blood sampling and mitochondrial measurements, including some measurements about 1.5 hours after dosing. They do not establish a preferred morning, evening, pre-workout or bedtime schedule for community use. Stacks Most preserved stack language is class adjacency or an SS-31 comparison, not evidence for combining SS-20 with SS-31, MOTS-c, humanin, NAD precursors or antioxidants. No SS-20-specific combination RCT establishes synergy or sequence. Watch for Injection-site reactions (dominant clinical AE): Erythema, swelling, pain, and pruritus were the grand majority of treatment-emergent events — about 91% of TEAEs in Part 1 and 97% in Part 2 of the HD study; all ISRs described as mild, often minutes after injection, often resolving within about an hour.
Related
SS-31MOTS-cHumanin

Tap a line to jump into the full notes. Research only — may be wrong.

Timing context & sources

Half-life in the body

Day-7 apparent elimination half-life after SubQ SBT-020 was 3.13–4.14 hours across the 5, 15 and 25 mg cohorts.

The early-Huntington's study observed peak plasma concentration around 0.5–1 hour after dosing and no accumulation during the later 28-day 25 mg daily phase.

Small monitored patient cohorts and an investigational formulation do not establish healthy-user safety, tissue residence, a consumer redosing interval or SS-31 equivalence.

Felt duration people report

A reproducible SS-20-specific subjective onset or felt duration was not established.

The human study documented frequent mild local reactions and no overall mitochondrial pharmacodynamic improvement; the inspected public forum discussion reproduced SS-class literature but did not provide a firsthand SS-20 course.

Injection-site timing is not a systemic benefit clock, absence of indexed reports is not proof of no effect, and SS-31 experiences cannot be transferred to SS-20.

What people say 14

  • Community claims: First-person energy, recovery, or longevity logs specifically for SS-20 are sparse; most “benefits” repeated online are SS-31 class bleed or vendor adjacency copy. forum
  • Cardiolipin / IMM: Discussed as preserving mitochondrial structure via cardiolipin interaction at the inner membrane; reviews note it does not share SS-31’s full ROS-scavenging and mPTP-inhibition profile. animal
  • Ischemia–reperfusion (heart): Pretreatment or peri-reperfusion SS-20/SBT-20 reduced myocardial lipid peroxidation and infarct size in rat models; both SS-31 and SS-20 showed protection in classic Cho/Szeto-style work. animal
  • I/R dose examples (rodent, context only): Published designs include ~3 mg/kg IP (e.g., 30 min pre-occlusion + dose near reperfusion), IV infusions of 0.3 or 3 mg/kg/hour during ischemia–reperfusion, and single ~4 mg/kg neuro/cardio PD doses used for human-equivalent starting-dose math. animal
  • Isolated-heart / cell work: Ex vivo rat hearts with SBT-20 (~1 µM during reperfusion) reduced infarct fraction; cell studies report improved maximal mitochondrial respiration after H2O2 challenge and blunted ROS in isolated mitochondria. lab
  • Neuroprotection (MPTP / PD-like): Systemic SBT-020/SS-20 attenuated injury and improved neurotransmitter release in MPTP mouse models; trial writeups cite ~4 mg/kg single dose attenuating ~40% of MPTP-induced dopamine depletion, plus protection of dopaminergic neurons and reduced apoptosis in SN4741 cells. animal
  • Dopaminergic cell assays: Both SS-31 and SS-20 dose-dependently reduced MPP+-related cell death in SN4741 dopamine cells in classic Szeto papers; isolated brain mitochondria work used ~50–100 µM ranges for both peptides against MPP+-induced respiration collapse. lab
  • Kidney / CRF: SBT-20 (SS-20) papers report renal protective signals — lower mtROS/inflammation, recovery of renal function markers, less necrotic/inflammatory histology, restored mito morphology, down-regulation of NF-κB-p65, TNF-α, and Drp1 with up-regulation of Mfn2 in chronic renal failure models. animal
  • Dynamics markers: Linked in some models to less pathologic fission (Drp1) and better fusion markers (Mfn2) — structural mito quality talk rather than acute stimulant feel. animal
  • Huntington’s program intent: SBT-20/SBT-020 was positioned to improve neuronal mitochondrial bioenergetics and potentially slow neurodegeneration; SS-31 (predecessor) had shown mito structure/function normalization in mutant Htt-expressing cell models, motivating the sibling program. trial
  • Human PD outcome (important): In early-stage HD patients, 25 mg SC daily × 28 days was safe but did not significantly change overall calf-muscle τPCr, visual-cortex 31P-MRS, PBMC mitochondrial membrane potential, or motor/neurocognitive batteries vs placebo. trial
  • Posthoc human signal: Exploratory split suggested more improvement in patients with worse baseline mito dysfunction (e.g., longer τPCr / lower ∆Ψm) than in those with relatively preserved function — authors hypothesized the cohort’s milder-than-expected mito impairment helped explain the null primary PD picture. trial
  • Where SS-20 fails as “SS-31 control”: In several oxidative-stress setups (e.g., tBHP cytotoxicity; T2D leukocyte SIRT1 / leukocyte–endothelium interaction work), SS-31 worked and SS-20 did not — papers use that to argue Dmt-dependent scavenging matters for those endpoints. lab
  • Honest framing: Preclinical multi-organ mito protection is real in the literature; consumer-style benefit claims for healthy users are not supported by a dense log base or positive human PD primary endpoints. forum

Doses people talk about 14

  • Human folklore / gray market: Stable, widely repeated mcg/mg-per-day SS-20-only protocols are far thinner than SS-31’s 5–10–20–40 mg culture. When a number is invented in chats, it is often a copy-paste of SS-31 bands without primary SS-20 support. forum
  • SS-31 paste risk (critical): Forums and vendor blurbs sometimes map SS-31 injectable bands (e.g., ~2–5 mg start, ~5–10 mg common, ~10–20+ mg “higher”) onto SS-20 without trial or diary grounding — treat any such chart as unsupported transfer, not SS-20 consensus. forum
  • Route assumed when any community dose is named: Subcutaneous research injection, mirroring the HD trial and SS-class practice. forum
  • Uncertainty flags: Mislabeling (SS-20 vs SS-31), low independent third-party testing, and purity/fill variance make any cross-vendor mg claim fragile. forum
  • Healthy-volunteer background (cited in trial): Subcutaneous single- and multiple-ascending-dose assessments of 5, 10, 20, and 30 mg were described as safe/tolerable, with dose-related injection-site reactions — used as background for patient dosing. trial
  • PK summary (HD patients, Part 1 day 7): Apparent elimination half-life roughly ~3.1 h (5 mg), ~3.9 h (15 mg), ~4.1 h (25 mg); rapid absorption with early Cmax; exposures roughly dose-related; no accumulation over 28 days of daily SC in Part 2 trough sampling. trial
  • Urine recovery (trial): By 24 h post-dose, roughly ~27–45% of dose recovered unchanged in urine (majority in first 6 h) in the published noncompartmental discussion. trial
  • In vitro concentrations (lab only): Classic papers use nM–µM peptide on cells/mitochondria (examples include ~1 µM in reperfused hearts; ~50–100 µM on isolated mitochondria in older MPP+ work) — not injectable self-admin math. lab
  • Clinical ≠ self-admin chart: 5 / 15 / 25 mg HD study arms and 5–30 mg healthy-volunteer SC bands are investigational study protocols, not public wellness recipes. trial
  • Framing: All figures below are discussed trial, preclinical, or thin community amounts — research/educational context only, not prescriptions, advice, or consumption guidance. forum
  • Human clinical (SBT-020 HD program): Part 1 multiple ascending dose — 5 mg, 15 mg, or 25 mg subcutaneously once daily for 7 days (6 active + 2 placebo per cohort). trial
  • Human clinical Part 2: Selected dose 25 mg SC once daily for 28 days (re-randomized active vs placebo). Authors framed 25 mg as the hypothesized effective-and-tolerable multi-week dose after MAD. trial
  • Starting-dose math from animals (trial text): Preclinical PD doses around 4 mg/kg (MPTP mouse neuroprotection; rat I/R cardioprotection) were converted to a human equivalent dose of ~0.76 mg/kg, or roughly ~4.5 mg for a 60 kg human — informing a low clinical start near 5 mg. trial
  • Animal ranges (context only — not human recipes): Mouse/rat work clusters around ~0.3–4 mg/kg parenteral single or short-course designs (IP, IV infusion, SC depending on paper); some SS-class neuroprotection reviews list ~0.5–5.0 mg/kg body-weight bands for SS-31/SS-20-type peptides. animal

How it may feel 8

  • Sparse diary culture: No well-indexed week-by-week SS-20 self-experiment set comparable to SS-31, MOTS-c, or GH secretagogues. forum
  • Borrowed SS-31 timelines: Longevity forums that mention SS-20 often paste SS-31 expectations (steadier energy by weeks 2–4, reassess at 4–8 weeks). That is class bleed, not SS-20 diary consensus. forum
  • Months 2–3+: Continuous-use consumer SS-20 anecdotes are scarce; the published HD program stopped at 28 days of multi-dose PD. forum
  • No subjective change: Community caution when the compound is even discussed: first re-check product identity (SS-20 vs SS-31 vs empty vial), purity, and whether expectations were pure SS-31 lore — not an automatic dose-escalation cue. forum
  • Hours–day 1 (clinical + community): Not a stimulant kick. In the HD trial, SC absorption was rapid (Cmax roughly 0.5–1 h); the dominant acute experience in clinic was injection-site reaction (erythema, swelling, pain, pruritus), usually mild, often within minutes, often resolving within about an hour. trial
  • Days 1–7: Trial Part 1 used 7-day multiple ascending doses (5 / 15 / 25 mg SC daily) without overall mito PD shifts; wellness users who try any SS peptide often report site sting more than systemic energy in week one. SS-20-specific early “feel” logs remain rare. trial
  • Weeks 1–4: Part 2 used continuous daily 25 mg SC for 28 days — the main human “feel/function” window on record — and still showed no overall mitochondrial or clinical function separation from placebo on pre-specified readouts. trial
  • Clinical ≠ wellness mapping: Huntington’s safety/PK blocks, UHDRS scores, and 31P-MRS τPCr recovery are disease-trial endpoints — they do not define a consumer energy timeline. trial

Cycles people discuss 7

  • No consensus consumer cycle: There is no standard 4-/8-/12-week SS-20 on/off culture with dense logs. forum
  • Borrowed SS-31 cycle talk: Continuous daily use, 4–8 week eval windows, or “3 months on / 1 month off” language occasionally appears beside SS-20 only because people treat all SS peptides as one bucket — weakly grounded for SS-20 alone. forum
  • Why people would pause (if experimenting at all): Cost of a low-volume research chem, daily needles, injection-site reaction fatigue (very common in the HD trial), and null subjective change. forum
  • Stop / reassess rules discussed: Re-verify compound identity and whether goals were pure SS-31 lore; track something concrete (energy diary, training metrics) rather than escalating on silence. forum
  • Documented clinical blocks: 7-day MAD (Part 1) → ≥1-month washout → 28-day continuous daily SC (Part 2) in the same early-HD cohort design. trial
  • Long-term consumer safety DB: Open-ended healthy-user SS-20 safety series are not established; the longest multi-dose human PD window in the main published study is 28 days at 25 mg SC daily. trial
  • Program framing: Investigational SBT-020 used multi-week clinical blocks with safety, PK, and mito PD — not bodybuilding-style blast/cruise. trial

Timing 9

  • Why timing debates are quiet: Low adoption → fewer practical “pre-workout vs bedtime” fights than high-volume injectables. forum
  • Human plasma half-life (published): In early-HD patients at day 7 of daily SC, apparent elimination half-life was roughly 3–4 hours and fairly dose-independent across 5 / 15 / 25 mg cohorts (~3.13 / 3.94 / 4.14 h in the paper’s day-7 summary). trial
  • Absorption: Rapid after subcutaneous injection; peak plasma concentration commonly occurs around ~0.5–1.0 h post-dose in the clinical PK description. trial
  • Accumulation: Weekly trough sampling over 28 days of daily 25 mg SC did not show accumulation. trial
  • Exposure variability: Trial noncompartmental notes described variability generally under ~26% for Cmax and AUC(0–last) in Part 1 profiles. trial
  • Renal contribution: Meaningful fraction excreted unchanged in urine within 24 h; geometric mean renal clearance figures in the paper did not suggest active secretion as a dominant story. trial
  • Why still daily in clinic: Short plasma residence + once-daily SC study design (class parallel to SS-31 programs) even though terminal half-life is only a few hours. trial
  • Downstream / tissue lore: Mitochondrial structure and function changes in animal models may outlast plasma presence — community borrows this “membrane effect > blood half-life” line from the SS class without SS-20-specific tissue half-life charts. animal
  • Timing of day: No strong morning-vs-evening injection consensus for SS-20; clinical admins were protocol-timed around PK/PD draws (including ~1.5 h post-dose for some mito measures). trial

More on what it is 8

  • Why people mention it: Sibling analog next to elamipretide (SS-31) in class explainers, control peptide in many SS-31 papers, and a named clinical candidate (SBT-020) with published human PK/safety. forum
  • Not the same as: Not SS-31/elamipretide/Forzinity, not MOTS-c/humanin (mitochondrial-derived peptides), not an approved longevity or consumer drug, not a stimulant. forum
  • Identity trap: Low gray-market volume + similar “SS” branding means mislabeling, SS-31 substitution, or class-bleed claims are a recurring caution in forums that mention it at all. forum
  • What it is: Synthetic aromatic–cationic tetrapeptide Phe–D-Arg–Phe–Lys–NH2 (often written H-Phe-D-Arg-Phe-Lys-NH2), one of the original Szeto–Schiller (SS) class peptides alongside SS-02, SS-19, and SS-31. trial
  • Clinical names: Stealth BioTherapeutics advanced it as SBT-20 / SBT-020 for mitochondrial function in early Huntington’s disease (EudraCT 2016-003730-25; published van Diemen et al., Br J Clin Pharmacol 2021). trial
  • Vs SS-31 structure: Shares the alternating aromatic–basic motif and IMM/cardiolipin targeting story, but lacks 2′,6′-dimethyltyrosine (Dmt) — the residue most papers credit for direct ROS-scavenging / phenolic antioxidant chemistry in SS-31 and SS-02. lab
  • Why it still works in some models: Even without classic scavenging, SS-20 can preserve mitochondrial structure, improve respiration under stress, and lower pathologic ROS production in ischemia–reperfusion and other injury models — mechanism talk centers on cardiolipin binding / bioenergetic optimization rather than mopping free radicals after the fact. animal
  • Evidence honesty: Dense preclinical literature; one well-described early-HD SC program with clear safety/PK and no overall pharmacodynamic win on mito readouts; almost no first-person wellness diary culture compared with SS-31. trial

Stacks 8

  • Vs SS-31 (primary comparison, not a stack): Discussed as the non-Dmt sibling / historical control peptide. Dual SS-20 + SS-31 stacks are low-volume and poorly documented; most serious talk is which analog, not both. forum
  • Why someone might still name SS-20: Cardiolipin/IMM targeting without Dmt; positive I/R and some neuro/renal models; curiosity about a Stealth sibling that is not elamipretide. forum
  • Mito class adjacency (not SS-20-only data): Nested in the same conversations as MOTS-c, humanin / SHLPs, NAD+ precursors (NMN/NR/NAD+), CoQ10/ubiquinol, PQQ, urolithin A, and methylene blue — mechanistic storytelling stacks without SS-20-specific combo RCTs. forum
  • SS-31 + MOTS-c culture bleed: The popular “stabilize membranes + AMPK signal” stack is an SS-31 community staple; transplanting it onto SS-20 is speculation. forum
  • Lifestyle confounders: Sleep, training load, metabolic health, and iron/thyroid status are co-credited whenever any mito peptide “worked” in sparse logs. forum
  • Separate syringes: If anyone co-runs multiple injectables, separate SC shots are preferred over untested co-mixing — generic peptide practice, not SS-20-specific stability data. forum
  • Why someone might prefer SS-31 in lore: FDA-path disease history (elamipretide / Forzinity for Barth), denser human trial corpus, and Dmt scavenging narrative. SS-20’s published HD PD was overall null. trial
  • Antioxidant table neighbors: MitoQ and other mitochondria-targeted antioxidants appear in the same review tables as SS peptides — adjacency, not a proven SS-20 combo protocol. trial

Storage notes 2

  • No mix instructions here: STUDresearch does not list reconstitution, diluent volumes, or syringe unit charts. People reconstitute many different ways and vial labels differ — that content creates more confusion than clarity. forum
  • Storage (general talk only): Unopened research products are usually kept cool, dry, and away from light per the seller label. Anything after first use is product-specific — follow the label, not a universal forum SOP. forum

Watch for 15

  • Consumer / research-chem gap: No large open healthy-user SS-20 safety series; quiet forums are not proof of safety. forum
  • Source / identity quality: Low volume raises mislabel, under-dose, SS-31 substitution, or empty-vial risk. forum
  • SS-31 outcome bleed: Borrowing elamipretide energy logs or Forzinity disease results onto SS-20 creates false confidence and identity blind spots. forum
  • Mito / malignancy caution (theoretical community talk): General caution talk for active malignancy history or complex primary mitochondrial disease appears in mito-peptide threads; not SS-20-specific RCT guidance. forum
  • Regulatory status: Research-chemical / investigational peptide — not an approved consumer wellness product; not interchangeable with pharmaceutical elamipretide. forum
  • Injection-site reactions (dominant clinical AE): Erythema, swelling, pain, and pruritus were the grand majority of treatment-emergent events — about 91% of TEAEs in Part 1 and 97% in Part 2 of the HD study; all ISRs described as mild, often minutes after injection, often resolving within about an hour. trial
  • Dose-related local irritation: Injection-site pruritus and pain were most often noted in the 25 mg cohort during MAD. trial
  • Systemic safety (study): SBT-020 was judged safe at all studied doses (through 25 mg SC daily × 28 days in patients; healthy-volunteer background up to 30 mg SC bands). Non-ISR AEs were few and roughly balanced with placebo in the published summary. trial
  • Histamine check: Plasma histamine at 15 and 30 minutes post-dose was not elevated in the trial’s ISR investigation — mechanism of local reactions remained unclear. trial
  • Labs / vitals / ECG: No clinically significant lab, vital-sign, ECG, or physical-exam signal attributed to drug in the published safety narrative. trial
  • SAEs in the HD study: One patient had pneumonia then pulmonary embolism after Part 1 follow-up and before Part 2 dosing — assessed as unrelated given timing from last dose. trial
  • Mechanism-dependent nulls: Because SS-20 lacks Dmt scavenging, endpoints that required that chemistry in lab models (some pure oxidant challenges, some leukocyte/endothelium readouts) did not respond to SS-20 — relevant when marketing claims copy SS-31 wholesale. lab
  • Drug interaction charts: No established community interaction matrix for SS-20 with common meds; the HD protocol restricted known mitotoxic meds (e.g., statins, metformin) for PD-cleanliness — not a consumer interaction monograph. trial
  • Pregnancy / pediatric: Not characterized in consumer discussion; clinical program was adult early-HD only. trial
  • Disease context ≠ wellness risk: Early-HD trial populations, mito PD inclusion thresholds, and investigational monitoring do not map to healthy longevity self-experiment risk framing. trial

Updated: 2026-08-12

Evidence mix More trial/lab tags than forum tags Full: every bullet (trial + community). Use Scan for a faster bro-science read.
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