Retatrutide Pharmacokinetics
Retatrutide half-life, absorption, routes of administration, and clearance.
Half-Life & Dosing Cadence
Retatrutide has a reported elimination half-life of ~6 days. The half-life is the time it takes for blood levels to fall by half, and it's the single biggest driver of how often you dose. That's why the typical schedule lands around 1x weekly (titrated) at 1–12 mg — frequent enough to keep levels in a useful range without stacking up. Shorter half-lives mean more frequent dosing and faster clearance if you stop; longer ones mean steadier levels but a slower washout.
Administration & Absorption
Retatrutide is administered by subcutaneous injection (into the fat layer just under the skin). The primary route is subcutaneous. Subcutaneous delivery is absorbed steadily from the fat depot, giving smoother peaks than intramuscular dosing. Whichever route you use, rotate sites and follow sterile technique.
Reconstitution & Handling
Retatrutide ships as a lyophilized (freeze-dried) powder that you reconstitute before use — a common starting point is a 10 mg vial with 2 mL of bacteriostatic water. Add the water slowly down the vial wall, swirl (don't shake), and let it fully dissolve. Reconstituted peptide is refrigerated and used within its stability window; unmixed powder keeps far longer when stored cold and dark. Always confirm exact dosing math against your own vial and concentration.
Onset & Clearance
Because of its ~6 days half-life, Retatrutide reaches steady levels after a few consistent doses and clears the system within roughly four to five half-lives once you stop. Track how you respond over a defined block rather than judging any single dose, and give the compound enough consistent days before deciding whether it's working. This is educational information, not medical advice — review your protocol with a clinician.
Physicochemical and PK profile
- Molecular Formula
- C221H342N46O68
- Molecular Weight
- 4925.64 g/mol
- CAS Number
- 2381089-83-2
- Half-Life
- Approximately 6 days
- Sequence
- Modified 39 amino acid peptide with GLP-1, GIP, and glucagon receptor binding domains
- Solubility
- Formulated as ready-to-use solution for injection
- Storage
- Store at 2-8°C protected from light.
References
- Triple–Hormone–Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial · Jastreboff AM, et al. · 2023
- Jastreboff AM, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity, A Phase 2 Trial. N Engl J Med. 2023;389:514-526. · Jastreboff AM, Kaplan LM, Frías JP, Wu Q, Du Y, Gurbuz S, Coskun T, Haupt A, Milicevic Z, Hartman ML · 2023
- Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials. · Giblin K, Kaplan LM, Somers VK et al. · 2026
- Appetite, eating attitudes, and eating behaviours during treatment with retatrutide in adults with type 2 diabetes: Results of a phase 2 study · Kanu C, Boye KS, Poon JL, Goetz I, Williamson S, Lou J, Hartman ML, Martin CK, Coskun T · 2025
- Rosenstock J, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial. Lancet. 2023;402(10401):529-544. · Rosenstock J, Frias J, Jastreboff AM, Du Y, Lou J, Gurbuz S, Thomas MK, Hartman ML, Haupt A, Milicevic Z, Coskun T · 2023
- Effects of retatrutide on body composition in people with type 2 diabetes. Lancet Diabetes Endocrinol. 2025. · 2025
- Tirzepatide Once Weekly for the Treatment of Obesity · Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, Kiyosue A, Zhang S, Liu B, Bunck MC, Stefanski A · 2022
- Efficacy and safety of retatrutide, a novel GLP-1, GIP, and glucagon receptor agonist. PMC. 2024. · Abdrabou Abouelmagd A, Abdelrehim AM, Bashir MN, Abdelsalam F, Marey A, Tanas Y, Abuklish DM, Belal MM · 2025
- Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial. · Coskun T, Wu Q, Schloot NC et al. · 2025
- Once-Weekly Semaglutide in Adults with Overweight or Obesity · Wilding JP, Batterham RL, Calanna S, Davies M, Van Gaal LF, Lingvay I, McGowan BM, Rosenstock J, Tran MT, Wadden TA, Wharton S, Yokote K, Zeuthen N, Kushner RF · 2021
- Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatohepatitis. Nature Medicine. 2024. · 2024
- Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. · Sanyal AJ, Kaplan LM, Frias JP et al. · 2024