Peptidify
← Back to codex

Retatrutide

Aliases: LY3437943 · Triple G · GGG agonist

Last verified: 2026-09-23

Clinical trialsModerate evidencePeptidesHigh interest

The short version

Retatrutide is the high point of current metabolic science: a phase II trial showed ~24% average body weight loss at 48 weeks — the largest effect ever recorded in the peptide class. The glucagon component also brings lipid benefits. The short version: this is phase II — ~300 participants, 48 weeks. No published phase III, no long-term safety data, and the bradycardia and amylase/lipase increases seen in the study are signals that must be clarified. Gray markets already sell it — which is exactly what a monograph should make visible.

Identity & type

Molecular type
analog
Sequence / structure
39-mer triple agonist (GIP/GLP-1/glucagon)
Molecular weight
~4731 Da
Origin
Triple GIP/GLP-1/glucagon receptor agonist, in development as a subcutaneous anti-obesity drug.

Mechanism of action

Adds glucagon-receptor activation (increased energy expenditure, lipolysis) to the GIP/GLP-1 base.

Dosing & routes

Official / clinical context

No approved official document exists for Retatrutide. Any protocols mentioned are to be read as information, not as a recommendation.

Regulator-approved labeling and published study designs — never a recommendation.

Community-reported practice

In trials: titration to 12 mg SC weekly. Gray market: exceptionally fast weight loss (the largest of any GLP-1 in the community), but with more frequent nausea, tachycardia and dysesthesias; product quality unverified.

Unverified self-reports. Not medical advice. Not endorsement.

Expected effects (community)

Effects reported in community use: very rapid, apparently dose-dependent weight loss — larger than with any other GLP-1-class compound — accompanied by frequent nausea, tachycardia and dysesthesias; all anecdotal, as no approved product exists and gray-market quality is unverified.

Protocol — official vs community

Official / label

Phase 2/3 regimen: SC once weekly, titrated to 12 mg (phase 3 also tested 4 mg).

  1. 01Weeks 1–4: 2 mg weekly
  2. 02Weeks 5–8: 4 mg weekly
  3. 03Weeks 9–12: 8 mg weekly
  4. 04Week 13+: 12 mg weekly (phase 3 maintenance options 4 or 8 mg)

Duration: Trial-defined, chronic in design. Long-term cardiovascular outcomes still being collected.

GI events and dose-dependent heart-rate increase (2–4 bpm) drove the slow escalation schedule.

Community (anecdotal)

Gray-market vials claiming 'reta' doses of 2–10 mg weekly — none of this is validated; no pharmacokinetic data exists for non-pharmaceutical product.

Cycle:
Untested. Trial design is continuous.
Break:
Unknown — no data on interruption effects.

Using an investigational drug outside trials means accepting both unvalidated product and unmonitored risk. The trial titration above is the only real protocol that exists.

Human evidence

One large phase II trial (Jastreboff, NEJM 2023) with a dose-dependent effect; phase III ongoing.

Preclinical evidence

Preclinical characterization in obesity and type 2 diabetes models preceded the human program; animal data on body weight and glycemia are consistent with the phase II signal, and multiple Phase 1/2 trials followed.

Known risks

  • Nausea and vomiting (~40–60% at higher doses)characterized
  • Bradycardia recorded in phase IIcharacterized
  • Amylase/lipase increases — clinical significance unknowntheoretical

Teal: characterized in clinical/labeling contexts. Amber: theoretical or reported outside controlled settings.

Unknowns & evidence gaps

  • Full phase III efficacy and safety
  • Cardiac effects of bradycardia with chronic use

Frequently asked questions

References

  1. Jastreboff A.M. et al., Retatrutide phase II trial (N Engl J Med, 2023)
  2. TRIUMPH program — phase III registry records