Enter your doses below and see your estimated blood level curve instantly. No account required. Based on published Phase 1 PK data (Coskun et al. 2022).
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Model: 1-compartment, first-order SC absorption. Constants from Coskun et al. 2022 (T½ ≈ 147 h, ka ≈ 0.065 h⁻¹, Vz/F ≈ 8.3 L). This is a population-average estimate — individual levels vary.
Retatrutide has a half-life of roughly 6 days, which means each weekly injection adds to the drug still circulating from previous doses. This calculator uses a one-compartment pharmacokinetic model with first-order subcutaneous absorption, fitted to published Phase 1 clinical trial data (Coskun et al., Cell Metabolism, 2022). It simulates absorption, distribution, and elimination hour-by-hour to plot your estimated blood concentration curve, and calculates how close you are to steady state — the point where the amount entering your body each week equals the amount being eliminated.
The model uses population-average PK parameters from Coskun et al. 2022. Individual blood levels vary based on body weight, injection site, metabolism, and other factors. Treat the curve as a directional estimate, not a lab result. For a deeper explanation, see how the PK model works.
Steady state is reached when the amount of retatrutide entering your body each dose cycle equals the amount being eliminated. At that point your trough-to-peak levels stabilize. With retatrutide's ~6-day half-life, this takes roughly 4–5 weeks of consistent dosing. Read more about retatrutide half-life and dose stacking.
A one-compartment model with first-order subcutaneous absorption. The three key constants — elimination half-life (~147 h), absorption rate (ka ≈ 0.065 h⁻¹), and apparent volume of distribution (Vz/F ≈ 8.3 L) — come from Phase 1 clinical trial data published in Cell Metabolism.
No. The PK parameters are specific to retatrutide. Tirzepatide and semaglutide have different half-lives, absorption rates, and distribution volumes. See our retatrutide vs tirzepatide comparison for how they differ pharmacokinetically.
No — this calculator works entirely in your browser with no sign-up required. If you want to save your dose history, track trends over time, and get personalized dose reminders, you can create a free account.
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