What is retatrutide's half-life?

Retatrutide has a reported terminal half-life of roughly 6 days, or about 144 hours. This long half-life places it in the once-weekly long-acting class and is the basis for the weekly administration schedule used in the Phase 2 obesity trial. The figure is reproduced as a research reference, not medical advice.

Why is retatrutide dosed once a week?

Because the ~6-day half-life means plasma concentration only halves across a week, weekly administration keeps levels within a relatively stable band. A shorter-half-life compound would require daily dosing to maintain the same exposure; retatrutide's long half-life is exactly what enables the convenient once-weekly cadence.

How long does retatrutide take to leave the system?

It takes roughly five half-lives to fall to a negligible concentration, which for retatrutide is about 30 days — four to five weeks after the last administration. That is the working washout figure for a research model that needs to account for effectively complete clearance.

How long until retatrutide reaches steady-state?

Steady-state is approached over roughly five half-lives — about four to five weeks. This is why the trials held each titration step for around four weeks: it lets plasma concentration plateau at one dose level before escalating to the next.

Is retatrutide approved for human use?

No. Retatrutide is an investigational compound with no regulatory approval for human use. Titan Peptide Lab supplies it strictly as a research-use-only reagent for in-vitro laboratory work — not for human or animal consumption, and not for diagnostic, therapeutic, or preventative use.

Retatrutide · 10mg vial · research use only

Retatrutide half-life: about six days, and why it matters.

Retatrutide's pharmacokinetics are the reason its dosing schedule looks the way it does. The compound has a terminal half-life of roughly 6 days (~144 hours), which sets a once-weekly cadence, defines how long it lingers after the last administration, and dictates how long each titration step needs to be held. This page explains the half-life, clearance, and steady-state implications as a research reference — not medical advice.

Retatrutide 10mg vial — $199.99 Retatrutide dosage reference

The number: ~6 days

Retatrutide (LY3437943) has a reported terminal half-life of roughly 6 days, or about 144 hours. That places it firmly in the long-acting class alongside other once-weekly incretin agonists, and it is the single fact that explains the once-weekly schedule used throughout the Phase 2 obesity trial — one administration maintains a working plasma concentration across the full seven-day interval.

See the dosage reference →

Why dosing is once weekly

With a ~6-day half-life, plasma concentration only falls by about half across a week, so weekly administration keeps levels within a relatively stable band rather than spiking and crashing. A shorter-half-life peptide would need daily dosing to hold the same band; retatrutide's long tail is precisely what allows the convenient weekly cadence the trials adopted.

View the 10mg vial →

Time to steady-state

It takes roughly five half-lives to approach steady-state, which for retatrutide is about 30 days — four to five weeks. That is not a coincidence: the trials held each titration step for about four weeks, allowing concentrations to plateau at one dose level before escalating. Understanding this timing is essential for any research model that tracks exposure across a titration.

Titration intervals →

How long it takes to clear

After the last administration, the same five-half-life rule means retatrutide takes roughly 30 days to fall to a negligible plasma concentration. For a research model that includes a washout window — or one tracking the tail of exposure after a protocol ends — about a month is the working figure for effectively complete clearance.

Reconstituted shelf life →

Storage doesn't change half-life

The ~6-day half-life describes how the compound behaves once in solution and circulating — it is separate from vial stability. Lyophilized retatrutide is stable at room temperature in transit and refrigerated long-term; once reconstituted with bacteriostatic water it has its own refrigerated shelf life. Half-life is a pharmacokinetic property, not a shelf-life one.

Shelf life after mixing →

Research-use framing

These pharmacokinetic figures are reproduced from the clinical and research literature as a laboratory reference for in-vitro and modelling work — not as instructions for human use. Retatrutide is an investigational compound with no regulatory approval. Titan supplies it strictly as a research reagent, and nothing here is medical or dosing advice.

Research-use policy →

The detail, in plain terms

The pharmacokinetics, in one table.

Retatrutide's half-life drives almost every scheduling decision in the research — the weekly cadence, the four-week titration steps, and the ~30-day washout. These are the figures a research model actually uses.

Compound: Retatrutide (LY3437943) — triple GLP-1 / GIP / glucagon agonist.
Terminal half-life: ≈6 days (~144 hours).
Dosing cadence: Once weekly — the long half-life holds a stable plasma band.
Time to steady-state: ≈4–5 weeks (about five half-lives).
Clearance after last dose: ≈30 days to negligible plasma concentration.
Format: 10mg lyophilized vial, $199.99 — reconstitute before in-vitro use.

Questions researchers ask

Before you order.

What is retatrutide's half-life?: Retatrutide has a reported terminal half-life of roughly 6 days, or about 144 hours. This long half-life places it in the once-weekly long-acting class and is the basis for the weekly administration schedule used in the Phase 2 obesity trial. The figure is reproduced as a research reference, not medical advice.
Why is retatrutide dosed once a week?: Because the ~6-day half-life means plasma concentration only halves across a week, weekly administration keeps levels within a relatively stable band. A shorter-half-life compound would require daily dosing to maintain the same exposure; retatrutide's long half-life is exactly what enables the convenient once-weekly cadence.
How long does retatrutide take to leave the system?: It takes roughly five half-lives to fall to a negligible concentration, which for retatrutide is about 30 days — four to five weeks after the last administration. That is the working washout figure for a research model that needs to account for effectively complete clearance.
How long until retatrutide reaches steady-state?: Steady-state is approached over roughly five half-lives — about four to five weeks. This is why the trials held each titration step for around four weeks: it lets plasma concentration plateau at one dose level before escalating to the next.
Is retatrutide approved for human use?: No. Retatrutide is an investigational compound with no regulatory approval for human use. Titan Peptide Lab supplies it strictly as a research-use-only reagent for in-vitro laboratory work — not for human or animal consumption, and not for diagnostic, therapeutic, or preventative use.