Retatrutide Reconstitution Calculator

No. Retatrutide (LY3437943) is an investigational once-weekly triple agonist of GLP-1, GIP, and glucagon receptors, not regulatory-approved for any indication in the US, UK, or elsewhere. A completed Phase 3 RCT (TRANSCEND-T2D-1) confirms efficacy in type 2 diabetes (RCT), and Phase 3 obesity data from the TRIUMPH program report approximately 28.7% mean weight reduction. Products sold online or via gray-market vendors are unregulated: testing of products sold as retatrutide in Australia found composition and labelling inaccuracies.

Subcutaneous injection. All human data involve once-weekly subcutaneous dosing with dose-proportional pharmacokinetics and a mean half-life of approximately 6 days. Trial doses span 0.5–12 mg weekly with slow-escalation schedules; 12 mg is the maximal studied dose. No oral formulation is commercially available; an investigational oral nanoparticle formulation achieved only ~7% relative bioavailability in beagles (animal).

Dose-dependent and substantial. In the 48-week Phase 2 obesity RCT, 12 mg weekly produced 24.2% mean weight loss (22.8% at 8 mg), 63% of participants lost ≥20%, and DEXA-measured fat mass fell 23.2% (RCT). Placebo-subtracted loss was −22.1%. Weight loss progressed through 48 weeks without plateau. In type 2 diabetes, expect less: up to 16.9% at 36 weeks in Phase 2 and 11.5–15.3% at 40 weeks in the Phase 3 monotherapy trial. Phase 3 obesity data report ~28.7%, with 39.4% achieving ≥30%. Beyond weight, meta-analysis of RCTs shows SBP −6.79, DBP −2.46 mmHg; total cholesterol −21.9, LDL-C −13.1, triglycerides −40.9 mg/dL.

(RCT) Gastrointestinal events dominate: nausea, vomiting, diarrhea, constipation in 13–50% of participants, dose-dependent, mostly mild–moderate and easing with slow titration; discontinuation due to adverse events was 2–5% in the Phase 3 slow-escalation trial,. Practical initiation schedules that limit early GI symptoms start at 1–2 mg once weekly and increase by 1–2 mg every 2–4 weeks, holding at any step until symptoms settle (community protocol). Monitor for a dose-dependent chronotropic effect (heart-rate increase); retatrutide increases force of contraction in isolated human atrial preparations (in-vitro). Skin dysesthesia (burning/tingling) occurs and is dose-related in most trials. Class-typical risks include gallbladder disease, pancreatitis, and lean-mass loss. No severe hypoglycemia was reported in the Phase 3 T2D trial.

People with type 1 diabetes. Retatrutide has no established role in T1D; case reports document ketoacidosis or near-DKA (ketones 4.3–6.4 mmol/L; pH as low as 6.8) after use of online-purchased product, with GI illness and insulin omission as co-drivers (case report),. Do not use in T1D (practitioner consensus). In type 2 diabetes, standard sick-day practice is to temporarily withhold the dose during severe vomiting, diarrhea, or dehydration, which can otherwise raise ketoacidosis risk when oral intake falls and insulin is omitted (practitioner consensus). Pregnancy: no human data exist; GLP-1RA class guidance recommends discontinuation before conception. Avoid unverified gray-market product (composition, sterility, and dosing cannot be assured).

Efficacy scales with receptor coverage: semaglutide ~16.0%, tirzepatide ~20.9%, retatrutide 24.2% in obesity trials. Placebo-subtracted weight loss: semaglutide −14.8%, tirzepatide −19.0%, retatrutide −22.1%. Network meta-analysis ranks retatrutide first for achieving ≥15% weight loss (OR 54.6) but with the highest adverse-event risk of the three. Phase 3 comparisons: 39.4% reached ≥30% weight loss with retatrutide versus ~10–15% with tirzepatide. In type 2 diabetes, retatrutide 12 mg reduced HbA1c by 1.94% from baseline (treatment difference vs placebo −1.12%) (RCT).

No defined maximum duration; safety/efficacy data support at least 48 weeks of continuous use. Obesity requires chronic treatment: discontinuation of GLP-1-based therapy typically leads to weight regain. Retatrutide releases slowly from subcutaneous depots (plasma remains detectable about 56 days after dosing ) and its ~6-day half-life supports true once-weekly dosing.

No published stability data exist for retatrutide specifically. Standard peptide practice (community protocol): store lyophilized vials refrigerated (2–8°C) protected from light; after reconstitution with bacteriostatic water, refrigerate and use within ~4-6 weeks; avoid heat and vigorous shaking. Vials from unregulated vendors carry no guaranteed sterility, potency, or identity.