RESEARCH MONOGRAPH · KDC-MN-083

Tirzepatide

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

81/100

Dual GIP/GLP-1 agonist with better weight-loss efficacy than semaglutide and an unexpectedly interesting GIP mechanism story

Tirzepatide is Lilly's GIP/GLP-1 dual agonist and it's genuinely a step beyond semaglutide on the efficacy curve. SURMOUNT-1 showed 22.5% mean body weight reduction at 72 weeks with the 15 mg dose, which is materially better than STEP-1's semaglutide numbers (14.9% at the same time horizon), and SURPASS for diabetes showed comparable advantages on HbA1c.

What we like, and what makes the pharmacology actually interesting beyond "more is more," is the GIP arm. The longstanding assumption was that GIP agonism would be obesogenic because endogenous GIP signaling promotes adipose tissue lipid storage. The fact that GIP agonism in the context of GLP-1 co-activation appears to produce additive or synergistic weight loss rather than counteracting GLP-1 has reshuffled the metabolic pharmacology field. The current best hypothesis is that GIP receptor desensitization plus central GIPR signaling in hypothalamic appetite regulation accounts for the paradoxical effect, but this is still active research. Either way, tirzepatide proved that dual incretin agonism works and changed how Novo Nordisk, Pfizer, Amgen, and several smaller players are thinking about next-generation candidates.

What we dont like is the same nausea, delayed gastric emptying, and GI tolerability profile as semaglutide, plus tirzepatide is even more recent so post-marketing safety surveillance is still building. The early signal on gastroparesis cases is probably real if rare. The thyroid C-cell signal is again present, again probably not clinically translatable, but the boxed warning is there.

Sourcing is challenging for research-grade material. Tirzepatide is a 39-residue dual-acylated peptide with a complex C20 fatty acid linker, even harder to synthesize cleanly than semaglutide. The price gap between reputable HPLC+MS verified material and the cheap stuff is large, and the cheap stuff is often where the acylation went wrong. Stick to vendors that publish full analytical packages.

For research on dual incretin pharmacology and the next generation of metabolic therapeutics, tirzepatide is the current reference compound and the GIP mechanism story is one of the most interesting open questions in metabolic biology. Genuinely promising and worth real research attention.

Evidence: 92
Mechanism: 88
Reliability: 90
Safety: 78
Sourcing: 60
Value: 60
Signal: 92
Staying power: 90

Plain-language summary Intrigue 93 / 100

Tirzepatide, sold as Mounjaro and Zepbound, is the first dual GLP-1 and GIP receptor agonist. By activating both incretin receptors, it produces more weight loss than semaglutide in head-to-head trials. Approved by the FDA in 2022. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

GIP/GLP-1 dual receptor agonist

A dual GIP and GLP-1 receptor agonist FDA-approved as Mounjaro (T2DM, 2022) and Zepbound (obesity, 2023), producing greater weight loss than GLP-1-only agents.

Abstract

Tirzepatide (Mounjaro, Zepbound; CAS 2023788-19-2; molecular weight 4813.54) is a dual GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptor co-agonist developed by Eli Lilly and approved by the FDA for type 2 diabetes (2022) and chronic weight management (2023). The compound is a 39-amino-acid synthetic peptide based on the GIP scaffold with modifications at positions enabling GLP-1 receptor agonism alongside GIP receptor activity. Mechanism is dual GIP/GLP-1 receptor agonism producing complementary effects: GIP engagement adds to GLP-1's glucose-dependent insulin secretion and contributes to weight regulation through fat metabolism modulation; GLP-1 contributes the central satiety, gastric emptying, and glucagon suppression effects. The combination produces substantially greater weight loss than GLP-1 monotherapy: SURMOUNT trials showed 15 to 22 percent weight loss over 72 weeks at 5 to 15 mg weekly doses. Reported research dose ranges in the literature span roughly 5, 10, and 15 mg weekly subcutaneous.

Mechanism of action

Dual GIP and GLP-1 receptor co-agonist; albumin-binding fatty acid extension for weekly dosing.

Reported research dose ranges

2.5 to 15 mg weekly subcutaneous.

References

Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med 2022.
Frias JP, et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2). N Engl J Med 2021.

Read the full monograph

The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, reported research dose ranges, sourcing and quality verification, reconstitution and handling, stack interaction considerations, and a curated reference list. Available as a research-use-only PDF download.

KDC-MN-083

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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Tirzepatide

Abstract

Mechanism of action

Reported research dose ranges

References

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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