Triple GIP / GLP-1 / glucagon receptor agonist (investigational)
Retatrutide half-life
Last reviewed 2026-11-08 · Sources cited for every value
Retatrutide
Investigational and not approved by the FDA or any other regulator. Eli Lilly has said it plans to submit a Biologics License Application in Q1 2027.
Reported half-life: 6 days.
Show chart data as a table
| Series | 1× t½ | 2× t½ | 3× t½ | 4× t½ | 5× t½ |
|---|---|---|---|---|---|
| Retatrutide | 6 days · 50% | 12 days · 25% | 18 days · 12.5% | 24 days · 6.25% | 30 days · 3.125% |
1 half-life
6 days
50% remaining
2 half-lives
12 days
25% remaining
3 half-lives
18 days
12.5% remaining
4 half-lives
24 days
6.25% remaining
5 half-lives
30 days
3.125% remaining
Source, population and method
In a 12-week phase 1b multiple-ascending-dose trial in adults with type 2 diabetes, the authors report that pharmacokinetics were dose proportional and the half-life was approximately 6 days.
- Reported value
- 6 days
- Measure
- Elimination half-life (source term: “half-life (not further qualified)”)
- Species
- Human
- Population
- Adults aged 20–70 with type 2 diabetes (52 received retatrutide, 72 enrolled)
- Route
- Subcutaneous
- Formulation
- Investigational solution for injection
- Context
- Repeated administration
- Study design
- Phase 1b, randomised, double-blind, placebo-controlled, multiple-ascending dose (4 US sites)
- Source type
- Peer-reviewed human pharmacokinetic study
- Evidence quality
- Moderate
- Last verified
- 2026-11-08
Value read from the published abstract; the abstract gives no range or variability and does not describe the PK method. A healthy-volunteer single-dose study (Coskun et al., Cell Metab 2022) reports PK that "supported once-weekly" use without a number in its abstract, so it is not shown.
Source: Urva S et al. 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. Lancet 2022;400(10366):1869-1881 · PMID 36354040 · DOI 10.1016/S0140-6736(22)02033-5 · NCT04143802 · 2022-11
Only one primary human half-life estimate is published in an accessible form. Phase 2 and phase 3 reports do not state a half-life in their abstracts, so the figure may change once fuller pharmacokinetic analyses or a label appear.
Idealized first-order elimination, R(t) = 100 × 2−t/t½. It ignores absorption, distribution, metabolites, individual physiology and effect duration, and is never a prediction for a person or a basis for timing anything.
Reported retatrutide half-life estimates
| Source | Half-life | Measure | Population | Route · form |
|---|---|---|---|---|
| Urva S et al | 6 days | Elimination half-life | Adults aged 20–70 with type 2 diabetes (52 received retatrutide, 72 enrolled) | Subcutaneous · Investigational solution for injection |
Urva S et al
In a 12-week phase 1b multiple-ascending-dose trial in adults with type 2 diabetes, the authors report that pharmacokinetics were dose proportional and the half-life was approximately 6 days.
- Reported value
- 6 days
- Measure
- Elimination half-life (source term: “half-life (not further qualified)”)
- Species
- Human
- Population
- Adults aged 20–70 with type 2 diabetes (52 received retatrutide, 72 enrolled)
- Route
- Subcutaneous
- Formulation
- Investigational solution for injection
- Context
- Repeated administration
- Study design
- Phase 1b, randomised, double-blind, placebo-controlled, multiple-ascending dose (4 US sites)
- Source type
- Peer-reviewed human pharmacokinetic study
- Evidence quality
- Moderate
- Last verified
- 2026-11-08
Value read from the published abstract; the abstract gives no range or variability and does not describe the PK method. A healthy-volunteer single-dose study (Coskun et al., Cell Metab 2022) reports PK that "supported once-weekly" use without a number in its abstract, so it is not shown.
Source: Urva S et al. 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. Lancet 2022;400(10366):1869-1881 · PMID 36354040 · DOI 10.1016/S0140-6736(22)02033-5 · NCT04143802 · 2022-11
Where sources differ: Only one primary human half-life estimate is published in an accessible form. Phase 2 and phase 3 reports do not state a half-life in their abstracts, so the figure may change once fuller pharmacokinetic analyses or a label appear.
What is known, and what is not
Known
- A phase 1b trial reports dose-proportional pharmacokinetics and a half-life of approximately 6 days.
- The estimate is from adults with type 2 diabetes after repeated subcutaneous administration.
- Retatrutide carries a fatty diacid moiety, the same albumin-binding strategy that lengthens other once-weekly incretin peptides.
Not yet established
- A published range or variability for the half-life, and how it differs by population (for example, obesity without diabetes).
- Label-grade pharmacokinetics: there is no FDA label because retatrutide is not approved.
- How the half-life relates to the duration of any effect.
Retatrutide's regulatory status is re-checked at every review. This page does not describe any regimen and nothing here should be read as one. See how values are selected.
What the curve can and cannot tell you
The curve is an idealized first-order elimination model. It is a mathematical illustration of what a half-life means, not a medical prediction. It does not model:
- Patient-specific pharmacokinetics
- Drug absorption from the site of administration
- Multi-compartment distribution
- Active metabolites
- Receptor occupancy
- How long a clinical effect lasts
- Individual blood concentrations
- Drug interactions
- Changes in kidney or liver function
A half-life describes how fast a concentration falls once absorption and distribution are complete. It is not the same as how long an effect lasts, and five half-lives is a mathematical landmark (about 3 % remaining in the idealized model), not a guaranteed washout or a safety threshold. Half-life vs duration of action.
Frequently asked questions
What is the half-life of retatrutide?
The only primary human estimate published in accessible form is approximately 6 days, reported by Urva et al. (Lancet 2022) from a 12-week phase 1b trial of subcutaneous retatrutide in adults with type 2 diabetes.
Is retatrutide FDA-approved?
No. As of the review date retatrutide is investigational. Eli Lilly has said it plans to submit a Biologics License Application to the FDA in Q1 2027. There is no approved label and no approved use.
Why is the uncertainty high?
The value comes from one phase 1b study, read from its abstract, which gives no range or variability. Phase 2 and 3 reports do not state a half-life in their abstracts. A future label or full pharmacokinetic analysis may report a different or more precise figure.
Does a 6-day half-life mean the effect lasts 6 days?
No. Half-life describes how fast plasma concentrations fall. How long an effect lasts depends on receptor activity, tissue exposure and physiology, which the half-life does not capture.
How does it compare with tirzepatide and semaglutide?
Their labels report about 5 days (tirzepatide) and about 1 week (semaglutide). The numbers are close, but they come from different study types and populations, so the comparison is approximate and says nothing about which is better.
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Retatrutide research profile
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