Retatrutide has no approved indication as of mid-2026. All dosage figures on this page describe clinical research protocols, not prescribing guidance. Retatrutide is accessible only through registered clinical trials.
Retatrutide Dosage in Clinical Research
A documentation of the dose levels, escalation schedules, pharmacokinetics, and administration route used in Phase 1, Phase 2, and Phase 3 Retatrutide clinical trials. All figures refer to enrolled trial participants only.
Dose Levels Studied Across the Trial Program
2 mg once weekly; escalating every 4 weeks to target maintenance doses of 4 mg, 9 mg, or 12 mg.Retatrutide dosage in clinical research has ranged from 0.5 mg to 12 mg administered once weekly by subcutaneous injection. The specific dose levels studied differ by trial phase and population.[5][1][2][9]
| Trial phase | Doses studied | Duration | Key dosage outcome |
|---|---|---|---|
| Phase 1b (T2D) | 0.5, 1, 3, 6, 9, 12 mg once weekly | 12 weeks | Dose-proportional PK; −8.96 kg at 9 mg[5] |
| Phase 2 obesity | 1, 4, 8, 12 mg once weekly | 48 weeks | −7.2% (1 mg) to −24.2% (12 mg)[1] |
| Phase 2 T2D | Up to 12 mg once weekly | 36 weeks | −16.9% weight; HbA1c −2.02%[4] |
| Phase 3 TRIUMPH-1 | 4, 9, 12 mg once weekly | 80 weeks | 4 mg: −19.0%; 9 mg: −25.9%; 12 mg: −28.3%[9] |
| Phase 3 TRIUMPH-4 | 9, 12 mg once weekly | 68 weeks | 12 mg: −28.7%[10] |
Dose-Escalation Schedule
Dose escalation is used across all Retatrutide clinical trials to manage gastrointestinal tolerability during treatment initiation. The standard approach used in the TRIUMPH Phase 3 program initiates treatment at 2 mg once weekly, then escalates every 4 weeks until the assigned maintenance dose (4 mg, 9 mg, or 12 mg) is reached.[9]
In Phase 2 trials, escalation schedules varied by cohort but followed the same principle: lower starting doses for a specified number of weeks before titrating to the target maintenance dose.[1][4] Dose-escalation is the mechanism by which nausea and other GI adverse events — most prominent in early treatment weeks — are managed to acceptable rates.
The dose-dependent efficacy signal is strong and monotonic across all studied levels: each step up in maintenance dose produced a larger mean weight reduction in both Phase 2 and Phase 3 data.[1][9][11]
How Is Retatrutide Administered?
Subcutaneous injection, once weekly. This is the only route of administration studied in published Retatrutide trials. All Phase 1, Phase 2, and Phase 3 data reported to date were generated using subcutaneous injection.[5][1][4][9]
The once-weekly interval is enabled by Retatrutide’s approximately 6-day plasma half-life, which results from its C20 fatty diacid conjugation enabling albumin binding.[14] Peak plasma concentration is reached 12–72 hours after injection.[14] No oral formulation of Retatrutide has been reported in published clinical trial data.
Retatrutide Half-Life and Pharmacokinetics
The terminal plasma half-life of Retatrutide is approximately 6 days in human Phase 1b pharmacokinetic data (Urva et al., Lancet 2022).[5] Pharmacokinetics are dose-proportional across the studied range of 0.5 mg to 12 mg.
The extended half-life is the result of the C20 fatty diacid conjugation attached to the peptide backbone via a lysine-17 linker. This moiety enables non-covalent albumin binding in plasma, dramatically slowing renal clearance and proteolytic degradation — the same albumin-binding strategy used in other once-weekly injectable compounds in the incretin class.[14]
Peak plasma concentration is achieved 12–72 hours post-subcutaneous injection. Hepatic metabolism proceeds without CYP450 enzyme involvement, indicating no cytochrome P450-mediated drug-drug interaction risk.[14] Drug-drug interaction studies for non-CYP pathways are ongoing in the TRIUMPH program.
How Long Does Retatrutide Take to Work?
In Phase 2 obesity trial data, meaningful appetite suppression was documented within the first 4 weeks of treatment. Statistically significant body weight reduction was detectable by approximately week 8. Maximum weight loss accrued progressively over the full 48-week Phase 2 treatment period, with no plateau observed at 48 weeks in the 12 mg group — suggesting ongoing efficacy that had not yet reached a ceiling by trial end.[22]
In Phase 3 TRIUMPH-1 data (80 weeks), the weight trajectory similarly continued to accrue through the observation window, with the endpoint of approximately 30.3% mean reduction in participants with BMI ≥35 reached at 104 weeks.[9]
GI adverse events — the primary tolerability issue — were most prominent during the dose-escalation weeks. As participants reached and maintained their assigned doses, GI event rates declined.
See Retatrutide side effects for the adverse event profile documented in Phase 2 and Phase 3 data.