# Retatrutide Dosage: What Trials Have Studied — Not Medical Guidance > Retatrutide dosage from Phase 1b, Phase 2 obesity, diabetes, and MASLD trials. Study-design facts only — no human dosing advice, no reconstitution recipes, no medical guidance. Study-design facts from published Phase 1b and Phase 2 protocols. Not dosing guidance. Not a prescription. ## What this page is and is not Retatrutide is an investigational drug. It is not approved. It does not have an official prescribing label or dosing guidelines. This page documents what Eli Lilly's clinical trial protocols administered — dose levels, escalation schedules, routes, and durations — as study-design facts drawn from published research. These are not recommendations. They are not guidance. They are the numbers that appeared in peer-reviewed trial publications, summarized here for documentary purposes. The reason this distinction matters: retatrutide is a potent compound with real, dose-dependent adverse effects. The dose-related nausea and dose-dependent heart-rate elevations documented in Phase 2 trials were managed with medical oversight — regular monitoring, dose escalation protocols, and clinical supervision. Research-labeled material obtained outside trials does not come with that oversight. This page describes what trials studied; what to do with that information is not within the scope of this digest. ## Retatrutide dosage as studied in Phase 1b The Phase 1b trial (Urva S et al., *The Lancet*, 2022) [4] enrolled 72 adults with type 2 diabetes. The doses studied were: - **0.5 mg** subcutaneous once weekly - **1.5 mg** once weekly - **3 mg** once weekly - **3/6 mg** (step escalation: 3 mg weeks 1–4, then 6 mg) - **3/6/9/12 mg** (step escalation: 3→6→9→12 mg, each step held for several weeks) Route: subcutaneous injection (under the skin), once weekly, over 12 weeks. The half-life established in this trial was approximately 6 days [4], which supports once-weekly dosing with a stable trough-to-peak exposure. See [retatrutide half life](/half-life) for the pharmacokinetic basis of that dosing interval. ## Retatrutide dosage as studied in Phase 2 obesity and diabetes trials **Phase 2 obesity trial** [1] — Doses studied: 1 mg, 4 mg, 8 mg, and 12 mg subcutaneous once weekly. Duration: 48 weeks. The trial used fixed doses rather than the step escalations of the Phase 1b; tolerability was managed by the trial's dose-escalation scheme in which participants started at lower doses before reaching their randomized maintenance dose. **Phase 2 type 2 diabetes trial** [2] — Doses studied: 0.5 to 12 mg subcutaneous once weekly, with stepwise dose escalation. Duration: 36 weeks. The escalation was structured specifically to manage GI tolerability — the principal challenge with incretin-class agents at higher doses. **Phase 2 MASLD substudy** [5] — Same dose groups as the obesity trial (1, 4, 8, 12 mg), same once-weekly subcutaneous route. Duration: 48 weeks, with primary endpoint at 24 weeks. A 2026 expert review [15] notes that HbA1c reductions of up to 2.16% were observed across dose groups and that GI events are meaningfully tied to the rate and starting point of dose escalation — findings that guided Phase 3 protocol design. **Dose escalation as a protocol feature** — All published protocols structured dose escalation over weeks because retatrutide's GI effects are dose-related. In trials, escalation pace was supervised by clinicians who could pause, reduce, or discontinue based on tolerability. That supervision does not exist outside clinical trials. ## Retatrutide dosage — what does not exist There is no approved formulation of retatrutide. There is no manufacturer-specified reconstitution protocol, storage standard, or concentration specification for any consumer or research product. The trial drugs used in Phase 1/2 were pharmaceutical-grade investigational products prepared to Good Manufacturing Practice (GMP) standards under clinical trial authorization. Gray-market vials are not that product. **How to reconstitute retatrutide** — There is no standardized answer to this question because no approved product with a reconstitution standard exists. The published trials used pre-filled pharmaceutical formulations under clinical supervision; no reconstitution protocol was published in the papers. ## How to reconstitute retatrutide This is one of the most-searched questions about retatrutide online, and the honest answer is that there is no verified, standardized reconstitution protocol for retatrutide — because no approved pharmaceutical product of retatrutide exists. Clinical trial formulations are pharmaceutical-grade, GMP-manufactured, and administered under medical supervision; they are not reconstituted from lyophilized powder by end users. Gray-market vials sold as "research retatrutide" come with no pharmaceutical identity verification, no sterility certification, and no concentration guarantee. This digest does not provide reconstitution recipes for gray-market injectable compounds. ## Route, frequency, and storage in trials **Route studied** — Subcutaneous injection once weekly across all Phase 1 and Phase 2 trials. No oral or intranasal formulations of retatrutide have been published in the literature to date. **Frequency** — Once weekly. This is supported by the approximately 6-day half-life [4], which ensures trough plasma concentrations remain above pharmacologically relevant levels with a weekly injection interval. **Storage** — No consumer or research-product storage standard exists for retatrutide. Clinical trial formulations are held to pharmaceutical cold-chain standards. Stability data for gray-market preparations are not available. --- A methodical reading of the published retatrutide trial record — Phase 1b pharmacokinetics through Phase 3 program, every figure walked to its source and the investigational status held in plain view; not a clinic, not a telehealth service, and nothing here dispensed or prescribed.