GLP-1

Retatrutide Dosage, Protocol & Research Guide

Evidence grade Human clinical trialBy Sam, MBA

MW 4,731 g/mol

Dosage, protocol, reconstitution and storage reference for Retatrutide, with a reconstitution calculator, vial sizes and cited research.

Dose overview

Every range below is taken from the cited source and carries its evidence grade.

Human data and community reports

Human data and community reports
Source	Population	Dose	Frequency	Route	Duration	Evidence
Phase 2 obesity trial (N Engl J Med 2023, doi 10.1056/NEJMoa2301972; 338 adults)^[2]	human338 adults with obesity (BMI 30 or higher) or overweight (BMI 27 to under 30) plus at least one weight-related condition, phase 2 trial	1–12 mg^[2]subcutaneous, trial dose arms 1, 4, 8 and 12 mg once weekly (some arms started at 2 or 4 mg); 1 mg is the lowest arm	once weekly	subcutaneous	—	Human clinical trialStudy details from the source: Phase 2 obesity trial (N Engl J Med 2023, doi 10.1056/NEJMoa2301972; 338 adults): subcutaneous once weekly for 48 weeks at 1 mg, 4 mg (initial dose 2 mg or 4 mg), 8 mg (initial dose 2 mg or 4 mg), or 12 mg (initial dose 2 mg), versus placebo
TRIUMPH-2 phase 3 trial (Lancet 2026, doi 10.1016/S0140-6736(26)01861-1; NCT05929079; adults with obesity and type 2 diabetes)^[3]	humanadults with BMI 27 or higher and type 2 diabetes, phase 3 trial	4–12 mg^[3]subcutaneous, trial dose arms 4, 9 and 12 mg once weekly; 4 mg is the lowest arm	once weekly	subcutaneous	—	Human clinical trialStudy details from the source: TRIUMPH-2 phase 3 trial (Lancet 2026, doi 10.1016/S0140-6736(26)01861-1; NCT05929079; adults with obesity and type 2 diabetes): self-administered subcutaneous injections once weekly of retatrutide 4 mg, 9 mg or 12 mg, or placebo; primary timepoint week 80

Evidence grades: A approved label, B human trial, C observational, D animal study, E community-reported.

Reconstitution calculator

Vial size (mg)

Bacteriostatic water added (mL)

Target amount per draw (mcg)

Syringe (U-100)

Sizes in the Pepcore catalogue10 mg 20 mg 30 mg

Concentration: 5 mg/mL
Volume to draw: 0.05 mL
Units on a U-100 syringe: 5 units
Draws per vial: 40

Properties

CAS: Not yet recorded
Molecular weight: 4,731 g/mol
Formula: Not yet recorded
Sequence: Not yet recorded
Aliases: LY3437943
Vial sizes (mg): 10, 20, 30, 60

Study duration

48 weeks^[2] Human trial

Duration of the cited study. It describes the source and is not a recommended cycle; no off period is stated. Source

Storage notes

Lyophilized: Not yet recorded from a cited source
Reconstituted stability (days): Not yet recorded from a cited source

Side effects, contraindications and regulatory status

Reported side effects

Phase 2 trial (NEJM 2023, 48 weeks): the most common adverse events were gastrointestinal, dose-related, mostly mild to moderate, and partly mitigated by a 2 mg rather than 4 mg starting dose.^[2] Human trial
Phase 2 trial: dose-dependent increases in heart rate peaked at 24 weeks and declined thereafter.^[2] Human trial
TRIUMPH-2 phase 3 (Lancet 2026, type 2 diabetes): diarrhoea 27%, 34%, 34% at 4, 9, 12 mg vs 13% placebo; nausea 14%, 21%, 28% vs 8%.^[3] Human trial
TRIUMPH-2: dysesthesia 4%, 6%, 7% at 4, 9, 12 mg vs 1% placebo; hypotension 1%, 5%, 6% vs under 1% placebo.^[3] Human trial
TRIUMPH-2: permanent discontinuation for adverse events or death was 4% (4 mg), 12% (9 mg), 8% (12 mg) vs 5% placebo; 7 deaths in total, all judged unrelated to study drug by investigators.^[3] Human trial

Cautions from reviews and trials

Trial exclusions, not labelled contraindications (no label exists): the phase 2 trial excluded personal or first-degree family history of MEN 2 or medullary thyroid carcinoma (registry NCT04881760).^[4] Human trial
Trial exclusions, not contraindications: the phase 2 trial excluded diabetes, acute or chronic pancreatitis, symptomatic gallbladder disease, and eGFR below 45 mL/min/1.73 m2 (registry NCT04881760).^[4] Human trial
Trial exclusions, not contraindications: the phase 2 trial excluded pregnancy, breast-feeding or intent to conceive, uncontrolled high blood pressure, and recent heart attack, stroke or heart failure hospitalization (NCT04881760).^[4] Human trial
Trial exclusions, not contraindications: TRIUMPH-2 excluded type 1 diabetes, personal or family history of MTC or MEN 2, and prior pancreatitis (registry NCT05929079).^[5] Human trial

Regulatory status

Investigational: Lilly Q2 2026 results (2026-08-05) state plans to submit a Biologics License Application to FDA in Q1 2027; the source states no approval^[1] Source

Report any adverse reaction to a qualified healthcare professional.

What the research says

Summaries of the cited studies, each with its evidence grade.

Phase 2 obesity trial (N Engl J Med 2023, doi 10.1056/NEJMoa2301972; 338 adults)^[2]
Human trial human
Phase 2 obesity trial (N Engl J Med 2023, doi 10.1056/NEJMoa2301972; 338 adults): subcutaneous once weekly for 48 weeks at 1 mg, 4 mg (initial dose 2 mg or 4 mg), 8 mg (initial dose 2 mg or 4 mg), or 12 mg (initial dose 2 mg), versus placebo
Human clinical trial
TRIUMPH-2 phase 3 trial (Lancet 2026, doi 10.1016/S0140-6736(26)01861-1; NCT05929079; adults with obesity and type 2 diabetes)^[3]
Human trial human
TRIUMPH-2 phase 3 trial (Lancet 2026, doi 10.1016/S0140-6736(26)01861-1; NCT05929079; adults with obesity and type 2 diabetes): self-administered subcutaneous injections once weekly of retatrutide 4 mg, 9 mg or 12 mg, or placebo; primary timepoint week 80
Human clinical trial

Compare vial sizes

Compare vial sizes
Size	Price	Doses available from the vial Calculated	Cost per dose Calculated
10 mg	$89.99	10	$9.00
20 mg	$114.99	20	$5.75
30 mg	$229.99	30	$7.67

Cost per dose uses the listed partner price and the reference dose cited on this page. Prices change; check the product page.

Calculated from a default of 2 mL water (adjustable).

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Frequently asked questions

What dose figures are published for Retatrutide?

Cited figures on this page: 1-12 mg once weekly, subcutaneous, trial dose arms 1, 4, 8 and 12 mg once weekly (some arms started at 2 or 4 mg); 1 mg is the lowest arm [2] (Human clinical trial, evidence grade B); 4-12 mg once weekly, subcutaneous, trial dose arms 4, 9 and 12 mg once weekly; 4 mg is the lowest arm [3] (Human clinical trial, evidence grade B). These are summaries of published sources, not medical advice. Each figure links to its source in the references.

What study duration is cited for Retatrutide?

The cited duration is 48 weeks, with no off period stated (Human clinical trial). It describes the source, not a recommendation.

What is the regulatory status of Retatrutide?

Investigational: Lilly Q2 2026 results (2026-08-05) state plans to submit a Biologics License Application to FDA in Q1 2027; the source states no approval

Compound facts

What is the molecular weight of Retatrutide?

Recorded molecular weight: 4,731 g/mol.

What is the CAS number of Retatrutide?

Not yet recorded.

How is Retatrutide stored in the laboratory?

Not yet recorded from a cited source.

Sources

https://pubchem.ncbi.nlm.nih.gov/compound/172898051

PubMed IDs: 35985340, 37366315

References

Numbered sources used on this page. Markers in the text link here.

sec.gov
Phase 2 obesity trial (N Engl J Med 2023, doi 10.1056/NEJMoa2301972; 338 adults) pubmed.ncbi.nlm.nih.gov Human trial
TRIUMPH-2 phase 3 trial (Lancet 2026, doi 10.1016/S0140-6736(26)01861-1; NCT05929079; adults with obesity and type 2 diabetes) pubmed.ncbi.nlm.nih.gov Human trial
clinicaltrials.gov Human trial
clinicaltrials.gov Human trial

Vial sizes and protocols

10 mgPartner size
Doses per vial
10
20 mgPartner size
Doses per vial
20
30 mgPartner size
Doses per vial
30