Trial Protocol Dosing Structure
The published Phase 2 trial (Jastreboff et al., New England Journal of Medicine, 2023) tested retatrutide across four once-weekly subcutaneous dose cohorts, with higher-dose cohorts using a stepped titration schedule rather than starting directly at the target dose. This page summarises that protocol structure as a research reference. It describes what was used in a controlled clinical trial setting — it is not instructional content for individual dosing decisions.
Dose Cohorts and Titration
| Target Cohort Dose | Titration Approach | Frequency |
|---|---|---|
| 1mg | Direct start, no titration required | Once weekly |
| 4mg | Stepped increase over several weeks | Once weekly |
| 8mg | Stepped increase over several weeks | Once weekly |
| 12mg | Longest titration schedule of the four cohorts | Once weekly |
Source: Jastreboff AM et al. N Engl J Med. 2023;389(6):514-526. Titration is used in GLP-1 class trial design to characterise tolerability alongside dose-response efficacy data. Exact weekly step intervals are detailed in the published trial protocol and supplementary appendix.
Cycle Length in Published Trials
The Phase 2 trial observation window ran 48 weeks from the first dose, including the titration period for higher-dose cohorts. TRIUMPH-1 Phase 3 results presented in June 2026 used an 80-week primary assessment and a 104-week extension. Trial treatment schedules belong to monitored study protocols, not personal-use cycling instructions. Source: Lilly: TRIUMPH-1, ADA 2026.
For the full weight-reduction data by cohort and timepoint, see Retatrutide Weight Loss Results.
Reconstitution Reference
Retatrutide is supplied as a lyophilised research-grade peptide. Reconstitution method, diluent choice, and storage conditions depend on the specific research protocol and intended laboratory application — researchers should follow their own institution's or protocol's procedures rather than a generic instruction set.
Use the reports published for the specific product, strength and batch to identify the methods and results available. Analytical testing must not be treated as authorisation for human use or evidence that a research vial matches the investigational product in a clinical trial.
Scope of This Reference
This page describes the dosing structure used in a published clinical trial protocol for research reference purposes. It is not a dosing guide, medical advice, or instructions for human administration. Retatrutide is not TGA-approved and is supplied by Eternal Peptides Wholesale for qualified laboratory research use only, not for human therapeutic use or consumption.
Research Materials Are Not Clinical-Trial Products
Eternal Peptides Wholesale supplies Retatrutide as RT10 (10mg, box of 10 vials, $544.50) and RT20 (20mg, box of 10 vials, $891.00), with Janoshik-verified batch testing published on each product page before purchase.
View Products & PricingFrequently Asked Questions
What dosing schedule did the Phase 2 trial use? +
The published Phase 2 trial (Jastreboff et al., 2023) used a once-weekly subcutaneous dosing schedule across four cohorts: 1mg, 4mg, 8mg, and 12mg. Higher-dose cohorts used a titration schedule, gradually increasing the dose over several weeks to the target cohort dose. For research reference only, not instructions for human use.
Was retatrutide titrated in the published trials? +
Yes. Cohorts targeting 4mg, 8mg, and 12mg used a stepped titration schedule starting from a lower dose and increasing at intervals, a common protocol design for GLP-1 class compounds to characterise tolerability data alongside efficacy. Exact titration intervals are detailed in the published trial protocol. For research use only.
How long did the trial cycle run? +
The published Phase 2 trial ran for 48 weeks. TRIUMPH-1 Phase 3 results presented in June 2026 used an 80-week primary assessment and a 104-week extension. These durations reflect trial protocol design, not general dosing recommendations. For research use only.
How is retatrutide reconstituted for laboratory use? +
Reconstitution method depends on the specific research protocol and intended application. Eternal Peptides Wholesale supplies retatrutide as a lyophilised research-grade peptide with batch-specific Certificate of Analysis documentation. Researchers should follow their own institution's or protocol's reconstitution and handling procedures. For qualified laboratory research use only.
Do laboratory test reports establish equivalence to clinical-trial retatrutide? +
No. A laboratory report describes the submitted sample and the tests performed. It does not establish clinical-trial formulation, manufacturing controls, stability, safety or therapeutic equivalence of a separately supplied product.