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Peptide Half-LifePowered by Peptide Library

Compare peptide half-lives

Side-by-side reported values with the context that makes them comparable, or not. Curves are the same idealized model applied to each value, never measured concentrations from one study.

Last reviewed 2026-11-08 · Sources cited for every value

Compounds to compare

Choose up to 5 compounds. Compounds without a reviewed human half-life are listed but not drawn.

Idealized elimination curves

Each curve is the same mathematical model drawn from each compound's reported half-life. These are not measured comparative concentrations: routes, formulations, populations and absorption differ, and none of this ranks one compound above another.

Comparison of idealized elimination curvesIdealized first-order elimination curves, percent of a starting reference amount remaining over 35 days. Semaglutide: half-life 7 days; Tirzepatide: half-life 5 days; Retatrutide: half-life 6 days. A mathematical illustration, not a prediction for any person.0%25%50%75%100%0102030Time (days)
  • Semaglutide
  • Tirzepatide
  • Retatrutide
Curves differ by line pattern as well as color; the table below lists every value with its source.
Show chart data as a table
Comparison of idealized elimination curves: time to each half-life and percent remaining
Series1× t½2× t½3× t½4× t½5× t½
Semaglutide7 days · 50%14 days · 25%21 days · 12.5%28 days · 6.25%35 days · 3.125%
Tirzepatide5 days · 50%10 days · 25%15 days · 12.5%20 days · 6.25%25 days · 3.125%
Retatrutide6 days · 50%12 days · 25%18 days · 12.5%24 days · 6.25%30 days · 3.125%
Side-by-side half-life evidence
CompoundReported half-lifeEstimateMeasurePopulationRoute · formEvidenceStatusLimitations
SemaglutideResearch profile ↗1 weekElimination half-lifeAdults with type 2 diabetes (clearance about 0.05 L/h stated for this population)Subcutaneous · Solution for injection (pen)HighFDA-approvedSteady state reported after 4–5 weeks of once-weekly administration; absolute bioavailability 89 %.
TirzepatideResearch profile ↗5 daysElimination half-lifeHealthy subjects and adults with type 2 diabetes (the label states PK is similar between them)Subcutaneous · Solution for injection (single-dose pen, vial, KwikPen)HighFDA-approvedSteady state is reported after 4 weeks of once-weekly administration; mean absolute bioavailability 80 %.
RetatrutideResearch profile ↗6 daysUrva S et alElimination half-lifeAdults aged 20–70 with type 2 diabetes (52 received retatrutide, 72 enrolled)Subcutaneous · Investigational solution for injectionModerateInvestigationalValue 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.

Reading a comparison

A longer half-life is not better or worse. It describes how slowly concentrations fall, which reflects molecular design (albumin binding, Fc fusion, protease resistance), route and formulation. It says nothing about efficacy, safety or suitability.

Values are only like-for-like when the measure, population and route match. A label value from a population pharmacokinetic analysis and a small single-dose study can share a chart, but the overlay is a visual aid, not a head-to-head result. Animal and laboratory values are never drawn as human curves.

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

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