Side-by-side · Research reference

FOXO4-DRIvsSS-31

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AAnimal-StrongHUMAN-REVIEWED12/45 cited

BPhase 3HUMAN-REVIEWED9/43 cited

FOXO4-DRI

Senolytic Peptide · D-Retro-Inverso

p53-TADMolecular targetBourgeois 2025

Pre-clinicalDevelopment stage

SQRoute (animal)

SQ · Animal models only

SS-31

Cardiolipin-binding · Mitochondrial protective

40 mgDaily doseSzeto 2014

Phase 3Evidence levelSzilagyi 2009 Szeto 2014

~3 hrHalf-life

SQ · Abdomen · Once daily

01Mechanism of Action

Parameter

FOXO4-DRI

SS-31

Primary target

FOXO4-p53 protein complex in senescent cellsBourgeois 2025 Tripathi 2021

Cardiolipin in inner mitochondrial membraneSzeto 2014

Pathway

FOXO4-DRI binds disordered p53 transactivation domain → displaces FOXO4 → nuclear p53 exclusion → p53-mediated apoptosis in senescent cells

Cardiolipin binding → cristae stabilisation → ETC integrity → reduced ROS + preserved ATP synthesisSzeto 2014 Szilagyi 2009

Downstream effect

Selective apoptosis of senescent cells; clearance restores tissue homeostasisTripathi 2021 Alameen 2026

Mitochondrial bioenergetic preservation; cardio-, neuro-, and reno-protective effects in animal + clinical studiesSzeto 2014

Feedback intact?

—

Origin

D-retro-inverso modification — inverted amino acid sequence, D-amino acids for protease resistance

Synthetic tetrapeptide D-Arg-Dmt-Lys-Phe-NH₂; cell-permeable, mitochondrial-selectiveSzeto 2014

Antibody development

—

02Dosage Protocols

Parameter

FOXO4-DRI

SS-31

Animal dose (mouse)

5 mg/kg

SQ injection, aged mouse model (testosterone restoration).

—

Frequency (animal)

Variable — single or intermittent dosing

Protocol-dependent; no standardised regimen.

—

Human equivalent (theoretical)

~0.4 mg/kg (28 mg / 70 kg adult)

Extrapolated using allometric scaling; no clinical validation.

—

Evidence basis

Animal / mechanistic

Multiple Phase 3 trials (Barth, AMD, ischemia-reperfusion)Szeto 2014 Szilagyi 2009

Route

SQ (animal)

No human route established.

—

Duration

Weeks to months (animal studies)

Senescent cell clearance observed within weeks.

Indefinite for mitochondrial disease; cycled for healthspan use

Clinical status

No human trials completed

—

Standard dose

—

40 mg / day SQ (clinical trials)Szeto 2014

Anecdotal community range 5-10 mg/day. Phase 3 trials use 40 mg.

Frequency

—

Once daily

Lower / starter dose

—

5 mg / day (anecdotal)

Reconstitution

—

Bacteriostatic water

Timing

—

Morning fasted preferred; pre-workout for exercise-induced mitochondrial stress

Half-life

—

~3 h plasma; tissue uptake longer

04Side Effects & Safety

Parameter

FOXO4-DRI

SS-31

Pulmonary hypertension risk

Senescent cell elimination promoted PH development/progression in rodent modelsBorn 2023

—

Context-dependent toxicity

Beneficial effects may be tissue/context-specific; elimination not universally protectiveBorn 2023

—

Off-target apoptosis

Theoretical risk of non-senescent cell apoptosis (selectivity not absolute)

—

Immune perturbation

Senescent cells contribute to immune surveillance; clearance effects unknown

—

Human safety unknown

No clinical trials — toxicity profile in humans not established

—

Injection site reaction

—

Erythema, mild pruritus

GI symptoms

—

Nausea (uncommon)

Headache

—

Reported in some Phase 3 trials

Cardiovascular

—

Cardio-protective in studies; no signal of harm

Long-term safety

—

Phase 3 data over 24+ months; no major safety signalsSzeto 2014

Pregnancy / OB

—

Avoid — insufficient data

Absolute Contraindications

FOXO4-DRI

·Pulmonary hypertension or vascular disease (preclinical evidence of harm)Born 2023
·Pregnancy / lactation (no safety data)

SS-31

·Pregnancy / breastfeeding
·Hypersensitivity to peptide

Relative Contraindications

FOXO4-DRI

·Active malignancy (senescence as tumour suppressor mechanism)
·Wound healing / tissue repair (senescent cells involved in fibrosis resolution)

SS-31

·None established

05Administration Protocol

Parameter

FOXO4-DRI

SS-31

1. Pre-clinical route

Subcutaneous injection used in rodent models. No human administration protocol exists.

Add bacteriostatic water per label. Light-protected handling.

2. Reconstitution (animal)

Typically reconstituted in sterile saline or PBS for animal experiments. Stability data limited.

SQ — abdomen or thigh. Rotate sites.

3. Dosing schedule

Variable — single bolus or intermittent dosing over weeks. No standardised human protocol.

Morning fasted; pre-workout for exercise-augmented mitochondrial stress.

4. Clinical development status

No registered human trials. Commercialisation by Cleara Biotech (Netherlands) in development phase.

Lyophilised: refrigerate, light-protected. Reconstituted: refrigerate ≤30 days.

5. Safety monitoring (proposed)

Would require cardiovascular assessment, pulmonary function, immune panel, tumour surveillance if human trials proceed.

29–31G, 4–8 mm insulin syringe.

06Stack Synergy

FOXO4-DRI

— no documented stacks

SS-31

+ MOTS-c

Moderate

View MOTS-c →

SS-31 and MOTS-c address mitochondrial decline through complementary axes. SS-31 protects existing mitochondrial structure (cardiolipin binding, cristae stabilisation). MOTS-c upregulates AMPK/PGC-1α, triggering biogenesis of new mitochondria. Together they pair preservation with renewal — anecdotally favoured in healthspan and post-cardio-event recovery protocols.

SS-31: 5–10 mg SQ · daily morning
MOTS-c: 5 mg SQ · 2× per week pre-workout
Primary benefit: Mitochondrial preservation + biogenesis