See how researchers reconstitute and dose retatrutide. Real vial size preferences, BAC water volumes, and dosage distribution from WPA calculator data.
As a newer triple receptor agonist (GIP, GLP-1, and glucagon), retatrutide reconstitution patterns are still evolving. This data captures current research trends—common dose selections, vial size preferences, and BAC water volumes from active WPA calculator sessions.
, 2023) and the Phase 3 TRIUMPH program from Eli Lilly. The Phase 2 study enrolled 338 adults with obesity across five arms—placebo plus four active retatrutide doses of 1mg, 4mg, 8mg, and 12mg once weekly—and ran for 48 weeks. The 12mg arm reached a mean weight reduction of roughly 24%, among the largest figures reported in any Phase 2 obesity trial. The Phase 3 TRIUMPH trials (TRIUMPH-1 in obesity, TRIUMPH-2 in type 2 diabetes, plus parallel programs evaluating cardiovascular outcomes and obesity-related comorbidities) standardized that into a single escalation: 2mg start, with 4-week step-ups to 4mg, 8mg, and a 12mg target, all once weekly. Across both phases, every dose actually evaluated long-term sits at 1mg or above—nothing under that mark has been formally studied.
Retatrutide is the investigational triple GIP/GLP-1/glucagon agonist (Eli Lilly's LY3437943), and the research peptide drawing the most interest for next-generation weight-loss studies. It ships as a lyophilized powder reconstituted with bacteriostatic water before use.
The glucagon arm — absent from semaglutide and tirzepatide — is hypothesized to increase resting energy expenditure and accelerate lipolysis, potentially explaining the larger weight-loss signal seen in early-phase data. Like other incretin agonists, retatrutide also slows gastric emptying and amplifies glucose-dependent insulin secretion.
A 338-person Phase 2 obesity trial (Jastreboff et al., NEJM 2023) reported mean weight reduction of approximately 24.2% at 48 weeks on the 12mg weekly arm — the largest figure published for any incretin therapy to date. Parallel Phase 2 work in T2D (Rosenstock et al., Lancet 2023) showed A1C reductions of 2.0–2.2% across 4–12mg arms. Phase 3 readouts from TRIUMPH-1 through TRIUMPH-4 are expected 2025–2027.
Retatrutide has a reported half-life of ~6 days, and the dose intervals researchers model most often fall around once weekly. Once-weekly dosing reaches steady state in about 5 weeks. The long half-life means each new dose lands on a meaningful amount of leftover from the previous week. It is catalogued under Weight Loss on WPA.
67,174 Retatrutide reconstitution calculations have been logged by the WPA community. The most common dose entered is 2mg (13,929 calculations). The most common bacteriostatic water volume is 2mL. The most popular vial size is 10mg (19,645 sessions). The most common dosing frequency is once weekly (9,905 logged protocols), followed by 2x/week (1,896).
These figures come from anonymized WPA peptide calculator sessions.
All figures shown are aggregated from anonymized calculator inputs and are provided strictly for independent laboratory research and educational purposes. They are community usage statistics — not dosing recommendations, and not medical advice.