What Is Eloralintide? Trial Doses, Half-Life & How to Track It

What eloralintide is and how it works

Eloralintide (development code LY3841136) is a 37-amino-acid analog of amylin, the hormone your pancreas releases with insulin after a meal. Amylin signals fullness and slows gastric emptying through receptors in the brainstem, a separate system from the GLP-1 pathway that semaglutide and tirzepatide use.

What sets it apart from cagrilintide is selectivity. In Lilly's cell assays, eloralintide activated the human amylin-1 receptor about 12 times more potently than the calcitonin receptor and 11 times more than the amylin-3 receptor, where cagrilintide is non-selective and acts on both amylin and calcitonin receptors. The Lilly authors' hypothesis is that this selectivity, and the slow, flat blood levels, explain why nausea looked lower in early trials. That is a hypothesis under test, not a settled fact.

Like the weekly GLP-1 drugs, it carries a fatty-acid chain (a C20 diacid) that binds albumin in the blood, which is what stretches its half-life to about two weeks and supports once-weekly dosing.

It is investigational. The Phase 3 ENLIGHTEN trials started enrolling between December 2025 and February 2026, with the main obesity trial reading out at week 64 and an estimated completion in 2030. Nothing below is a recommendation; these are the doses Lilly studied.

Doses studied in trials

There is no approved dose. The 48-week Phase 2 trial (263 adults with obesity or overweight, without type 2 diabetes) randomized people to placebo or one of six eloralintide arms, all once-weekly subcutaneous:

• Fixed doses: 1 mg, 3 mg, 6 mg or 9 mg every week for 48 weeks
• Escalation arm: 6 mg for 20 weeks, then 9 mg for 28 weeks
• Escalation arm: 3 mg for 4 weeks, 6 mg for 4 weeks, then 9 mg for 40 weeks

What the trials showed

Phase 2, week 48 (published in The Lancet, November 2025), mean change in body weight from a 109 kg average baseline: -9.5% at 1 mg, -12.4% at 3 mg, -17.6% at 6 mg, -20.1% at 9 mg (about 21 kg), -19.9% in the 6 to 9 mg arm and -16.4% in the 3 to 9 mg arm, versus -0.4% on placebo.

A 12-week Phase 1 study with no dose escalation (1.2, 3, 6 and 12 mg weekly, 100 participants) saw placebo-adjusted weight loss from 2.6% to 11.3%. Resting pulse fell with dose (about 14 bpm lower at 12 mg by week 12, versus 3 bpm on placebo), where GLP-1 drugs usually push heart rate up.

In a separate 48-week Phase 2b trial in adults with type 2 diabetes (367 people, reported September 2026), eloralintide alone produced 8.2% to 12.3% weight loss, tirzepatide 15 mg alone 14.8%, and the two combined (EloraTZP) 13.2% to 23.3%, with placebo at 3.0%. Lilly plans Phase 3 trials of a co-formulated product by the end of 2026.

Half-life & what it means for frequency

Phase 1 measured a terminal half-life of 310 to 366 hours (about 13 to 15 days) across 0.4 to 12 mg single doses, with peak concentration arriving a slow 3 to 5.5 days after the injection. That is roughly double cagrilintide (6.6 to 8.1 days) and semaglutide (about 7 days).

Two consequences. Steady state takes about four to five half-lives, so a given dose is not fully "in" for roughly two months, which is one reason the trial escalation arms held each step for at least four weeks. And the swing within a week is small (Lilly reported peak-to-trough ratios of 1.28 to 1.38 at steady state), so a dose a day late moves levels very little. The flip side: if a dose is not agreeing with you, it also takes weeks to wash out.

What to track & common side effects

The Phase 2 side-effect picture is dose-dependent, and the escalation schedule matters. Nausea was reported by 11% at 1 mg, 13% at 3 mg, 64% at 6 mg, 33% at 9 mg, 54% in the 6 to 9 mg arm and 25% in the 3 to 9 mg arm, against 14% on placebo. Fatigue ran 0%, 13%, 29%, 43%, 46% and 21% across the same arms versus 12% on placebo. The slow 3 to 9 mg ramp had the mildest profile of the higher-dose arms.

Decreased appetite, headache and fatigue were the most common events in Phase 1, and the authors reported depressed mood in three participants on 6 or 12 mg plus one case of persistent depressive disorder at 12 mg. In the type 2 diabetes trial, 0% to 10.8% stopped eloralintide alone because of side effects, versus 10.8% to 27% on the tirzepatide combination.

For tracking: log the weekly dose and the day it was taken, trend weight and waist weekly rather than daily, and note energy and mood alongside nausea, since those are the signals that set this compound apart from the GLP-1 drugs. If it is being run next to a GLP-1, log the two separately so a rough week points at the right compound.

Frequently asked questions