Published trial ladder

Retatrutide Phase 2 8 mg arm (4 mg start): published ladder and modeled levels

Updated by the GLP Ladder Editorial Team. Editorial policy.

Short answer

Retatrutide Phase 2 8 mg arm (4 mg start): 4/8 mg weekly, 4 weeks per step (Eli Lilly, hosted on ClinicalTrials.gov, Aug 29, 2022). The final 8 mg step begins in week 5. With t½ 6 days and R = 1.8033, the modeled amount peaks at 13.11 mg-eq. As published, not a recommendation; as of Oct 19, 2026.

Weeks per step
4 2 steps
Final step
8 mg from week 5
Modeled peak
13.11 mg-eq
Accumulation R
1.8033 t½ 6 d
Retatrutide Phase 2 8 mg arm (4 mg start): steps and modeled amountWeekly doses 4 mg, 8 mg; modeled amount peaks at 13.11 mg-equivalents.stable window05101520mg-eq02468101214161820weeks from start4 mg8 mg
  • Weekly dose (published steps)
  • Modeled amount (mg-eq)
  • Stable window
Steps start on a Monday (Jan 5, 2026) for illustration. Curve: modeled relative amount, not plasma concentration. Open in the Retatrutide plotter to change dates or doses.
Phase 2 8 mg arm (4 mg start): weeks, weekly dose and dates from a Jan 5, 2026 start (Eli Lilly, hosted on ClinicalTrials.gov, Aug 29, 2022)
WeeksWeekly doseFirst week starts
1–4 4 mg Jan 5, 2026
5 onward 8 mg Feb 2, 2026

Weekly modeled amounts

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20 weeks. Highlighted rows start a new dose step. Model details: model card.

Retatrutide Phase 2 8 mg arm (4 mg start): weekly peak, trough and average (mg-equivalents)
WeekStartsDose mgPeakTroughAverage
1Jan 5, 202643.56402.573
2Jan 12, 202645.2151.8423.889
3Jan 19, 202645.9572.6624.475
4Jan 26, 202646.2893.0284.736
5Feb 2, 202689.9863.1917.426
6Feb 9, 2026811.7155.1058.794
7Feb 16, 2026812.4885.9589.403
8Feb 23, 2026812.8336.3389.674
9Mar 2, 2026812.9876.5079.795
10Mar 9, 2026813.0566.5839.849
11Mar 16, 2026813.0866.6169.873
12Mar 23, 2026813.16.6319.884
13Mar 30, 2026813.1066.6389.888
14Apr 6, 2026813.1086.6419.89
15Apr 13, 2026813.116.6429.891
16Apr 20, 2026813.116.6439.892
17Apr 27, 2026—6.9043.094.746
18May 4, 2026—3.0751.3762.114
19May 11, 2026—1.370.6130.942
20May 18, 2026—0.610.2730.419

Sources

  1. Study Protocol J1I-MC-GZBF(b) for NCT04881760 (Prot_000.pdf). Eli Lilly and Company, hosted on ClinicalTrials.gov, Aug 29, 2022. Accessed Oct 19, 2026.
  2. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med 2023;389(6):514-526 (abstract via PubMed PMID 37366315; doi:10.1056/NEJMoa2301972), Jun 26, 2023. Accessed Oct 19, 2026.
  3. A Study of LY3437943 in Participants Who Have Obesity or Are Overweight (NCT04881760) - registry record with posted results. ClinicalTrials.gov (U.S. NLM), Sep 13, 2023. Accessed Oct 19, 2026.
  4. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial. The Lancet 2022;400(10366):1869-1881 (abstract via PubMed PMID 36354040; doi:10.1016/S0140-6736(22)02033-5), Oct 27, 2022. Accessed Oct 19, 2026.

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