GLP-1/GIP Agonist / SubQ / 2.5-15mg weekly
Tirzepatide
Tirzepatide came out of Eli Lilly's incretin program as LY3298176, a single 39-amino-acid peptide built on the GIP backbone and engineered to activate both incretin receptors at once. It reached US approval for type 2 diabetes in 2022 (Mounjaro) and for chronic weight management in 2023 (Zepbound).
In plain words
Tirzepatide is a lab-made peptide that switches on the receptors for two natural hormones at once, GIP and GLP-1, and it is engineered so that one injection lasts about a week. It is an approved prescription medicine, cleared in the United States for type 2 diabetes in 2022 and for long-term weight management in 2023. The evidence behind it comes from large randomized trials: a mean 20.9 percent body-weight reduction over 72 weeks against 3.1 percent on placebo, better blood sugar control than semaglutide in type 2 diabetes, more weight loss than semaglutide when the two were compared head to head, large reductions in sleep apnea, and far fewer people going on to develop type 2 diabetes over three years. Chemically it is a GIP molecule that was tuned until it also switched on the GLP-1 receptor, which it binds about 5-fold more weakly than the natural hormone does. Shortages after launch meant compounding pharmacies and grey-market vials covered much of the demand, and in that supply the purity of the raw peptide, the accuracy of the stated milligrams and the sterility of the fill are exactly the parts nobody is required to verify.
At a glance
| Half-life | 4.86 days |
|---|---|
| Tmax | 1.5 days |
| Route(s) | SubQ |
| Published dosing range | 2.5-15mg weekly |
| Vial strengths | 5, 10, 15, 20, 30 mg |
Reference data from the DosePlot canon -- not a protocol recommendation.
Serum curve
Single 8.75 mg dose by SubQ, rendered from the same engine that powers the interactive chart. Relative levels, not lab values.
What does the evidence show?
Two things are labeled separately here because they answer different questions. The tier is how a study was built. The distance chips are whether that study touched this molecule, by this route, in a population resembling the reader. A randomized trial of a different molecule keeps its tier and still says nothing about this compound.
| Finding | Tier | Distance from use | Study |
|---|---|---|---|
| In adults with obesity and without diabetes, tirzepatide 15 mg weekly produced a mean 20.9% body-weight reduction over 72 weeks, versus 3.1% with placebo (SURMOUNT-1). | rct | not recorded | Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity.New England Journal of Medicine 387(3):205-216, 2022 |
| In type 2 diabetes, tirzepatide beat semaglutide 1 mg on glucose control at every dose tested; at 15 mg, HbA1c fell 2.30 percentage points over 40 weeks versus 1.86 with semaglutide, with greater weight loss at all three doses (SURPASS-2). | rct | not recorded | Frias JP, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes.New England Journal of Medicine 385(6):503-515, 2021 |
| In an open-label randomized trial comparing the two drugs head to head at maximum tolerated doses (tirzepatide 10 or 15 mg versus semaglutide 1.7 or 2.4 mg) in adults with obesity and without diabetes, tirzepatide produced greater weight loss at 72 weeks: 20.2% versus 13.7% (SURMOUNT-5). | rct | not recorded | Aronne LJ, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity.New England Journal of Medicine 393(1):26-36, 2025 |
| In adults with obesity and moderate-to-severe obstructive sleep apnea, one year of tirzepatide cut the apnea-hypopnea index by 25 to 29 events per hour, versus about 5 with placebo, across the two SURMOUNT-OSA trials. | rct | not recorded | Malhotra A, et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity.New England Journal of Medicine 391(13):1193-1205, 2024 |
| Three years of tirzepatide in adults with obesity and prediabetes cut progression to type 2 diabetes by 93% relative to placebo: 1.3% versus 13.3% diagnosed by week 176 (hazard ratio 0.07). The gap narrowed but held after 17 weeks off treatment, at 2.4% versus 13.7% (hazard ratio 0.12). This is the SURMOUNT-1 population followed to week 176. | rct | not recorded | Jastreboff AM, et al. Tirzepatide for Obesity Treatment and Diabetes Prevention.New England Journal of Medicine 392(10):958-971, 2025 |
| Users who switched from semaglutide commonly report steadier appetite suppression that holds through the full week between injections, with less late-week rebound hunger. | anecdotal | not recorded | community reports aggregated from reddit, MESO-Rx, and similar forumsno study |
How did it get here?
- preclinical2013-2016
- Unimolecular GIP/GLP-1 co-agonists (nicknamed twincretins) show additive metabolic effects in rodents. Lilly engineers LY3298176: a GIP-based backbone carrying a 20-carbon fatty diacid for once-weekly dosing.
- first-human2018
- Phase 1 and phase 2 results publish: dose-dependent glucose and weight reductions in type 2 diabetes beyond what selective GLP-1 agonists had shown, moving the dual-agonist concept into phase 3.
- clinical-adoption2022
- After the SURPASS phase 3 program, FDA approval as Mounjaro for type 2 diabetes in May. Weeks later SURMOUNT-1 reports 20.9% mean weight loss at the top dose, the largest seen in an obesity drug trial to that point.
- clinical-adoption2023
- Approved as Zepbound for chronic weight management in November, the first dual GIP/GLP-1 agonist approved for obesity.
- grey-market2022-2025
- Tirzepatide ran the grey-market route in reverse: pharma product first, informal supply after. Persistent shortages put it on the FDA shortage list from late 2022, and compounding pharmacies plus grey-market lyophilized vials filled the gap at a fraction of list price. The shortage was declared resolved in late 2024, compounded copies were ordered wound down through 2025, and much of that demand moved to unregulated vials.
How is it made?
Tirzepatide is a synthetic peptide, made by chemistry rather than by engineered cells, and production happens in three stages.
1. Building the chain. The molecule is a single chain of 39 amino acids, assembled by solid-phase synthesis: the growing chain sits anchored to resin beads while coupling and washing cycles add one residue at a time. Two positions carry aminoisobutyric acid, a residue not found in ordinary protein. Those substitutions are the survival trick: DPP-4, the enzyme that destroys natural incretin hormones within minutes, cannot grip the altered backbone.
2. Attaching the fat. A 20-carbon fatty diacid is bonded through a short linker to the lysine at position 20. The fatty tail sticks to albumin, the most abundant protein in blood, and the albumin-bound fraction acts as a slow-release reservoir. That reservoir, on top of the DPP-4 resistance, stretches the half-life to about five days and is what makes once-weekly injection work. Semaglutide uses the same protraction chemistry; tirzepatide borrowed a proven trick.
3. Purification and fill. Preparative chromatography separates the finished 39-residue chain from the near-identical failures any long synthesis produces - chains missing a residue, or carrying the tail in the wrong spot. Pharmaceutical product is sterile-filled into single-dose pens under GMP batch testing. Grey-market product is typically freeze-dried into multi-dose vials, and there the purity of the raw peptide, the accuracy of the stated milligrams, and the sterility of the fill are exactly the parts nobody is required to verify.
Worth knowing
GIP spent decades as the written-off incretin: its insulin-boosting effect is blunted in type 2 diabetes, and animal studies found that blocking and stimulating the GIP receptor both cause weight loss, a paradox still not fully resolved. Tirzepatide's clinical results are what forced the field to take the receptor seriously again.
Campbell JE. Targeting the GIPR for obesity: To agonize or antagonize? Potential mechanisms.Molecular Metabolism 46:101139, 2021
Despite being shelved with the GLP-1 drugs, tirzepatide is chemically a GIP analog that acquired GLP-1 activity, not the reverse: Lilly built the 39-amino-acid backbone on the native GIP sequence, then tuned it until it activated both receptors.
Coskun T, et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept.Molecular Metabolism 18:3-14, 2018
Reconstitution
Tirzepatide ships lyophilized and is mixed before use; the published vial strengths are 5, 10, 15, 20, 30 mg. The water volume you add sets the concentration, not the dose -- the calculator turns a vial size and a water volume into mg/mL, draw volume, and units on an insulin syringe.
Open in the reconstitution calculatorWritten and reviewed by Evan Marlow, developer of DosePlot · Updated 2026-08-27
Not medical advice. DosePlot is an informational tool, not a healthcare provider, and using it creates no provider-patient relationship. Do not start, stop, or change any protocol without the approval of a licensed healthcare professional.
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