Tirzepatide: The Dual Receptor Agonist Explained

Q: How does tirzepatide work?

Where semaglutide mimics one hormone, tirzepatide mimics two: GLP-1 and GIP. That dual action is thought to drive the slightly greater appetite suppression and weight loss seen in the trials.

Q: What do the tirzepatide trials show?

Around 20–22% average weight loss over ~72 weeks in the weight-loss trial (Zepbound®). A1c reduction in type 2 diabetes (Mounjaro®). Cardiovascular outcomes: in SURPASS-CVOT, tirzepatide was non-inferior to dulaglutide for major cardiac events in type 2 diabetes. SURMOUNT-MMO, the outcomes trial in obesity without diabetes, is still running. Side-effect profile similar to semaglutide: mostly early GI effects.

Q: Is compounded tirzepatide the same as Zepbound, and can you still get it?

Compounded tirzepatide is not FDA-approved and is not interchangeable with Zepbound or Mounjaro. The FDA declared the tirzepatide shortage resolved in December 2024, and the deadlines to stop compounding under the shortage exemption passed in early 2025. A 503A pharmacy can still prepare a patient-specific formulation where the prescriber documents a clinically significant difference, but routine compounded tirzepatide is no longer a generally available option. Ask your provider which product you would receive and on what basis.

How tirzepatide targets both GIP and GLP-1 receptors, and what the SURMOUNT trials found.

Published August 30, 2026Updated September 13, 202610 min readWritten and fact-checked against the sources below

Read this first

Educational, not medical advice. Tirzepatide is a prescription medicine. Compounded tirzepatide is not FDA-approved.

Tirzepatide is the newer, dual-receptor GLP-1. It's the molecule behind Mounjaro® (type 2 diabetes) and Zepbound® (weight management), and it tends to produce a bit more weight loss than semaglutide in head-to-head comparisons.

How does tirzepatide work?

Where semaglutide mimics one hormone, tirzepatide mimics two: GLP-1 and GIP. That dual action is thought to drive the slightly greater appetite suppression and weight loss seen in the trials.

What do the tirzepatide trials show?

Around 20–22% average weight loss over ~72 weeks in the weight-loss trial (Zepbound®).
A1c reduction in type 2 diabetes (Mounjaro®).
Cardiovascular outcomes: in SURPASS-CVOT, tirzepatide was non-inferior to dulaglutide for major cardiac events in type 2 diabetes. SURMOUNT-MMO, the outcomes trial in obesity without diabetes, is still running.
Side-effect profile similar to semaglutide: mostly early GI effects.

Is compounded tirzepatide the same as Zepbound, and can you still get it?

Compounded tirzepatide is not FDA-approved and is not interchangeable with Zepbound or Mounjaro. The FDA declared the tirzepatide shortage resolved in December 2024, and the deadlines to stop compounding under the shortage exemption passed in early 2025. A 503A pharmacy can still prepare a patient-specific formulation where the prescriber documents a clinically significant difference, but routine compounded tirzepatide is no longer a generally available option. Ask your provider which product you would receive and on what basis.

Bottom line

Tirzepatide is the most potent of the current once-weekly GLP-1s on the weight-loss data, with a similar side-effect profile to semaglutide. Know brand vs. compounded, and manage it with a clinician. This is information, not a prescription.

Want this handled for you?

LunaRx — clinician-led GLP-1 care with a plan to come off

LunaRx connects you with a licensed clinician for an online evaluation. Depending on your state that is a live or a store-and-forward visit. If the clinician determines a GLP-1 is appropriate for you, a licensed pharmacy dispenses it — with a plan to come off when you’re ready. The prescribing decision is the clinician’s alone, and approval is not guaranteed.

Start the 2-minute eligibility checkIndependent site · by LunaRx · not medical advice

Sources

Primary sources for the claims in this article. Trial results are reported as published; prescribing information is the authoritative reference for dosing and safety.

1.
SURMOUNT-1: Tirzepatide Once Weekly for the Treatment of Obesity
Jastreboff AM, et al. · New England Journal of Medicine · 2022
Mean weight change of −20.9% on tirzepatide 15 mg at 72 weeks, in 2,539 adults without diabetes.
2.
SURPASS-CVOT: Cardiorenal Outcomes With Tirzepatide Compared With Dulaglutide in Patients With Diabetes and Cardiovascular Disease
SURPASS-CVOT post hoc analysis · 2025
Tirzepatide non-inferior to dulaglutide for MACE (12.2% vs 13.1%) and superior on the cardiorenal composite (HR 0.84).
3.
ZEPBOUND (tirzepatide) injection — full prescribing information
DailyMed, U.S. National Library of Medicine · 2026
Boxed warning for thyroid C-cell tumors, MTC/MEN 2 contraindications, and gastroparesis guidance.
4.
SURMOUNT-3: Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity
Nature Medicine · 2023
Additional weight loss when tirzepatide follows a lifestyle-intervention lead-in.
5.
FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize
U.S. Food and Drug Administration · 2025
Shortages resolved (tirzepatide December 2024, semaglutide February 2025) and the compounding enforcement deadlines that followed.

Get the weekly research update

New trials, FDA moves, and pricing shifts — one plain-English email a week. No spam.

Unsubscribe anytime. Read our privacy policy.