Lilly's triple agonist clears its pivotal obesity programme. Filing is planned for Q1 2027, which puts a prescription eighteen to twenty-four months away.
TRIUMPH-1, the 80-week Phase 3 weight-management trial of retatrutide, produced mean weight reduction of up to 30.3%, with topline results from TRIUMPH-2 and TRIUMPH-3 following in July 2026. Retatrutide is a first-in-class triple agonist targeting GIP, GLP-1 and glucagon receptors.
For context, a large review of 26 randomised trials across 15,491 adults without diabetes placed retatrutide at the top of the field at 24.2% against tirzepatide's 17.8% and subcutaneous semaglutide's 13.9% at their maximum evaluated doses. The TRIUMPH-1 topline sits above that estimate.
It is not available. Lilly plans a Biologics License Application in Q1 2027; with a standard review that puts approval in late 2027 at the earliest and realistically 2028. There is no legal access route outside clinical trial enrolment, and no mechanism to switch from tirzepatide.
Anything sold today as compounded or research-grade retatrutide is an unapproved substance outside clinical oversight. The research-use disclaimer on those products exists so the seller can say you were told.
Sources
- Lilly announcement of TRIUMPH-1 topline results, May 2026
- TRIUMPH-2 and TRIUMPH-3 topline results, July 2026
- TRIUMPH-1, NCT05929066 — source
Dated 2026-08-04. If this item is out of date or wrong, tell us through contact and the change is logged in corrections.
Primary sources
Clinical, dosing and regulatory statements on this page rest on the documents below. Links go to the publisher, not to a summary of it. Prices are not sourced here — they carry a verification date instead, and the reason is set out in the source ledger.
- ZEPBOUND (tirzepatide) full prescribing information — DailyMed, US National Library of Medicine. Dose ladder, contraindications, warnings, storage.
- FDA’s concerns with unapproved GLP-1 drugs used for weight loss — US Food and Drug Administration. Compounded GLP-1 risks, API import alert, cold-chain complaints.
- FD&C Act provisions that apply to human drug compounding — US Food and Drug Administration. Why a compounded preparation is lawful without being FDA-approved.
- Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1) — N Engl J Med 2022;387:205-216. Registration NCT04184622. The weight-reduction and adverse-event figures used across this site.
- The full source ledger — every primary source, what it supports, the date we read it, and the claims we deliberately do not source.