Key facts
- Eloralintide is an amylin receptor agonist. Tirzepatide (Zepbound, Mounjaro) is a GIP and GLP-1 receptor dual agonist. Both are once-weekly Lilly injections.[3]
- Best monotherapy results: eloralintide 20.1% at 48 weeks (phase 2) vs tirzepatide 20.9% at 72 weeks (SURMOUNT-1, 15 mg).[1][2]
- EloraTZP, eloralintide 9 mg plus tirzepatide 15 mg, gave 23.3% weight loss at 48 weeks vs 14.8% for tirzepatide 15 mg alone, in people with type 2 diabetes.[3]
- Tirzepatide is approved. Eloralintide and EloraTZP are investigational.[3]
Eloralintide vs Tirzepatide: Key Differences
Eloralintide works on amylin receptors while tirzepatide works on GIP and GLP-1 receptors, so they act on different appetite pathways and can be combined.[3]
| Feature | Eloralintide | Tirzepatide |
|---|---|---|
| Developer | Eli Lilly | Eli Lilly |
| Brand names | None (investigational) | Zepbound, Mounjaro |
| Receptors | Amylin (selective) | GIP and GLP-1 |
| Dosing | Once weekly injection | Once weekly injection |
| Best obesity trial result | -20.1% at 48 wk, 9 mg[1] | -20.9% at 72 wk, 15 mg[2] |
| Status | Phase 3 (ENLIGHTEN) | Approved |
Eloralintide vs Tirzepatide Weight Loss
Eloralintide 9 mg gave 20.1% mean weight loss at 48 weeks in phase 2, and tirzepatide 15 mg gave 20.9% at 72 weeks in SURMOUNT-1, so their top-dose results are similar on a longer timeline for tirzepatide.[1][2]
- Tirzepatide SURMOUNT-1 (2,539 adults, 72 weeks): 15.0% at 5 mg, 19.5% at 10 mg, 20.9% at 15 mg, against 3.1% on placebo. 57% on 15 mg lost at least 20%.[2]
- Eloralintide phase 2 (263 adults, 48 weeks): 9.5% at 1 mg up to 20.1% at 9 mg, against 0.4% on placebo.[1]
- The trials used different estimands and lengths, so treat the comparison as approximate.
Eloralintide With Tirzepatide: EloraTZP Results
Adding eloralintide 9 mg to tirzepatide 15 mg reduced weight by 23.3% at 48 weeks, against 14.8% with tirzepatide 15 mg alone, in a phase 2b trial of 367 adults with obesity and type 2 diabetes.[3]
Efficacy estimand, baseline weight 105.4 kg. Source: Lilly, 30 Sep 2026 (EASD 2026).
- HbA1c fell by up to 2.9 points with the combination, against 2.4 with tirzepatide 15 mg alone.[3]
- In the earlier 16-week phase 1, eloralintide 3 mg plus tirzepatide 5 mg gave 17% weight loss against 10% for tirzepatide 5 mg alone.[4]
- Discontinuation due to adverse events was 10.8% to 27.0% on EloraTZP, against 2.9% on tirzepatide alone.[3]
- Phase 3: AMPLIFY-1 (obesity, n = 2,115) and AMPLIFY-2 (type 2 diabetes, n = 1,000) test a single-injection co-formulation with a 100-week primary endpoint.[5][6]
Side Effects Compared
Both cause mainly gastrointestinal side effects; in SURMOUNT-1, 4.3% to 7.1% stopped tirzepatide because of adverse events, and combining the two raised discontinuation to 10.8% to 27.0% in the EloraTZP phase 2b.[2][3]
Lilly says side effects with EloraTZP were mostly mild or moderate, occurred mainly during dose escalation, and were more frequent with the combinations. The phase 3 programme uses an optimised escalation schedule.[3] Eloralintide alone: see eloralintide side effects.
Frequently Asked Questions
Is eloralintide better than tirzepatide?
Their top-dose results are similar: 20.1% at 48 weeks for eloralintide 9 mg and 20.9% at 72 weeks for tirzepatide 15 mg, in separate trials. Tirzepatide is approved; eloralintide is still in phase 3.
What is EloraTZP?
EloraTZP is Lilly’s investigational combination of eloralintide and tirzepatide. In a 48-week phase 2b in type 2 diabetes it reduced weight by up to 23.3%, against 14.8% with tirzepatide alone.
Can eloralintide be taken with tirzepatide?
Only within clinical trials. EloraTZP is being tested in phase 3 (AMPLIFY-1 and AMPLIFY-2). It is not approved, and nothing here is medical advice.
Is eloralintide a replacement for Zepbound?
No. Eloralintide is not approved. Lilly is testing it both alone and as an add-on to tirzepatide, the active ingredient in Zepbound.
Sources
- Eli Lilly press release, 6 Nov 2025: eloralintide phase 2 results
- Jastreboff AM, et al. Tirzepatide SURMOUNT-1. N Engl J Med 2022;387:205-216. DOI 10.1056/NEJMoa2206038
- Eli Lilly press release, 30 Sep 2026: EloraTZP (eloralintide + tirzepatide) phase 2b results
- Eli Lilly press release, 15 Sep 2026: EASD 2026 data including EloraTZP phase 1
- ClinicalTrials.gov NCT07881432, AMPLIFY-1 (EloraTZP)
- ClinicalTrials.gov NCT07881458, AMPLIFY-2 (EloraTZP)
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