retatrutide vs tirzepatide

updated October 25, 2026

retatrutide (tier S) vs tirzepatide (tier S): what each is, half-life and source counts side by side.

the difference

checked October 25, 2026

TRIUMPH-5 (NCT06662383), a phase 3, randomized, double-blind trial of retatrutide against tirzepatide in adults with obesity, is registered on ClinicalTrials.gov; on October 25, 2026 its record listed it as active and not recruiting, with primary completion estimated for November 2026 and no results posted.

• ClinicalTrials.gov NCT06662383, TRIUMPH-5

a PubMed search the same day found no published result from it.

• PubMed search: NCT06662383 or TRIUMPH-5 (October 25, 2026)

a Drugs@FDA search on October 24, 2026 found no FDA approval for retatrutide.

• Drugs@FDA search via openFDA: retatrutide, no matches (October 24, 2026)

tirzepatide is FDA-approved as Mounjaro for type 2 diabetes, including lowering cardiovascular risk in adults at high risk, and as Zepbound for long-term weight reduction and for obstructive sleep apnea in adults with obesity.

• Mounjaro prescribing information, DailyMed (revised 8/2026)
• Zepbound prescribing information, DailyMed (revised 8/2026)

retatrutide · tier S

the most potent weight loss drug ever tested. 24.2% in phase 2, then 28.3% in TRIUMPH-1 phase 3, 30.3% at two years. not approved yet.

tier rationale

now that the pivotal phase 3 obesity trial has read out (TRIUMPH-1: 28.3% weight loss at 12mg over 80 weeks, 30.3% at two years), reta has the strongest published obesity-drug efficacy in the catalog. Bariatric-surgery territory from a weekly shot. triple receptor mechanism adds glucagon agonism on top of tirz's dual mechanism, which pushes lipolysis and energy expenditure. S-tier based on phase 3 efficacy, but with meaningful open questions on safety and no announced approval date.

tirzepatide · tier S

A dual GIP and GLP-1 receptor agonist with distinct Zepbound and Mounjaro labels.

tier rationale

Tirzepatide is in S tier because large randomized trials have shown weight loss, improved blood-sugar control and reduced sleep-apnea severity. Zepbound and Mounjaro have US approvals for these uses.

at a glance

reptides grades the research record and cites the literature behind every call. research reference only; not medical advice.