Tirzepatide in 2026: The Trial Data, the Head-to-Head vs Semaglutide, and What Canada Approved
The dual agonist hit 22.5% mean weight reduction in SURMOUNT-1 and beat semaglutide outright in the first head-to-head trial. Here are the real numbers, the Canadian approval timeline, and the distinction that actually matters when you buy research-grade material.
- Tirzepatide (listed here as GLP-2/Tirz) is a dual GIP and GLP-1 receptor agonist — semaglutide targets one receptor, retatrutide three.
- SURMOUNT-1 (2,539 participants, NEJM, June 4, 2022) showed 22.5% mean weight reduction at 15 mg over 72 weeks versus 2.4% on placebo.
- SURMOUNT-5 was the first head-to-head against semaglutide: 20.2% versus 13.7% at 72 weeks (751 participants, NEJM 2025), with waist circumference down 18.4 cm versus 13.0 cm.
- In adults with type 2 diabetes and obesity, SURMOUNT-2 showed 15.7% mean reduction at 15 mg — lower, as expected in a diabetic population.
- Canada has approved tirzepatide three times: Mounjaro for type 2 diabetes since 2022, Zepbound for weight management in May 2025, and Zepbound for obstructive sleep apnea on June 11, 2026 — the only GLP-1 in Canada carrying that indication.
- The approved product is a prescription medicine dispensed by pharmacies. Research-grade material is not that product and is not a substitute for it.
- Supplied for in vitro laboratory research use only — not approved by Health Canada for therapeutic use and not for human or veterinary consumption.
The compound that proved two receptors beat one
Tirzepatide — listed in this catalogue as GLP-2/Tirz — is the compound that ended the argument about whether stacking incretin receptors actually does anything.
Semaglutide (Ozempic, Wegovy) engages one receptor: GLP-1. Tirzepatide engages two, adding GIP. For years that was a theoretical advantage, because nobody had run the two compounds against each other. The trial data now covers both the theory and the direct comparison, and both point the same way.
For the three-receptor version of the same idea, see our retatrutide Phase 3 breakdown.
SURMOUNT-1: the headline trial
Published in the New England Journal of Medicine on June 4, 2022. 2,539 participants randomised 1:1:1:1 to 5 mg, 10 mg, 15 mg or placebo, with the primary endpoint at 72 weeks.
| Arm | Mean weight reduction at 72 weeks | Average loss |
|---|---|---|
| Placebo | 2.4% | 5 lb (2 kg) |
| 5 mg | 16.0% | 35 lb (16 kg) |
| 10 mg | 21.4% | 49 lb (22 kg) |
| 15 mg | 22.5% | 52 lb (24 kg) |
About nine in ten participants on tirzepatide lost weight. At the time, a 22.5% mean reduction in a non-diabetic obesity population was the largest figure any pharmacological agent had produced in a trial of that size.
SURMOUNT-5: the head-to-head that settled it
This is the trial that matters most, because it removes the cross-trial guesswork. SURMOUNT-5 put tirzepatide directly against semaglutide — same protocol, same population, same duration.
751 participants, enrolled April 2023 to November 2024 across 32 sites, randomised to tirzepatide (10 or 15 mg) or semaglutide (1.7 or 2.4 mg), over 72 weeks. Published in the New England Journal of Medicine in 2025 (Aronne et al., 393(1):26-36).
**Result: 20.2% mean weight reduction on tirzepatide versus 13.7% on semaglutide (p<0.001)** — 22.8 kg against 15.0 kg. Waist circumference fell 18.4 cm on tirzepatide versus 13.0 cm on semaglutide, also p<0.001.
That is a 6.5 percentage-point gap under identical conditions. Cross-trial comparisons had suggested tirzepatide was ahead; SURMOUNT-5 confirmed it rather than merely implying it.
SURMOUNT-2: the diabetic population
In adults with obesity or overweight and type 2 diabetes, tirzepatide produced a mean 15.7% weight reduction at 15 mg over 72 weeks, published in The Lancet in 2023.
The lower figure is expected, not disappointing. Weight loss in people with type 2 diabetes is consistently harder to achieve across every agent in this class, which is why SURMOUNT-2 is reported separately rather than pooled with SURMOUNT-1.
Where tirzepatide sits in the class
| Compound | Receptors | Peak trial weight reduction |
|---|---|---|
| Semaglutide | GLP-1 | 14.9% (STEP-1, 68 weeks) |
| Tirzepatide | GIP + GLP-1 | 22.5% (SURMOUNT-1, 72 weeks) |
| Retatrutide | GIP + GLP-1 + glucagon | 28.3% (TRIUMPH-1, 80 weeks) |
The pattern is close to linear in receptor count, which is precisely why the field moved to triple agonists. But tirzepatide is the only one of the three that is both approved and backed by a published head-to-head win.
What Canada actually approved
This is where tirzepatide differs sharply from retatrutide, and it is worth being precise.
- —**Mounjaro (tirzepatide) for type 2 diabetes** — approved in Canada since 2022. Health Canada has since extended it to children aged 10 and older with type 2 diabetes.
- —**Zepbound (tirzepatide) for weight management** — approved by Health Canada in May 2025, for adults with a BMI of 30 or greater, or 27 or greater with at least one weight-related condition.
- —**Zepbound for obstructive sleep apnea** — approved June 11, 2026 for adults with obesity, making it the only GLP-1 drug in Canada carrying that indication. Health Canada was explicit that it is not an immediate replacement for CPAP, which remains first-line for moderate to severe cases.
**And here is the distinction that matters.** Those approvals cover a prescription pharmaceutical, manufactured to pharmacopoeial standards, dispensed by a pharmacist, prescribed and monitored by a clinician. Research-grade tirzepatide is a different thing entirely: a laboratory reagent, sold for in vitro work, with no prescription, no pharmacist and no clinical oversight attached. It is not the approved product, it is not equivalent to it, and it is not a cheaper route to it. Anyone telling you otherwise is selling you something.
What research-grade material is good for is laboratory work — receptor-binding studies, comparative incretin pharmacology, in vitro metabolic models — and for that, what matters is whether the vial contains what the label says.
Sourcing GLP-2/Tirz in Canada
For laboratory work, the supplier is the quality-control system. Popular Peptides supplies GLP-2/Tirz for in vitro research use:
- —**It ships from within Canada.** From Vancouver, BC, typically 2 to 5 business days, tracked and insured. No customs clearance, no border seizure, no three-week silence. Most research compounds bought in Canada arrive from overseas and take that risk on every order. Ours do not cross a border.
- —**Every batch is independently tested.** HPLC for purity, LC-MS for identity, by a third-party lab rather than by us. Published-batch HPLC purity has averaged above 99%. Look up any lot number and read the certificate of analysis yourself, or browse all published lab results.
- —**Priced and charged in Canadian dollars,** with card and Interac e-Transfer at checkout, and free shipping over $300 CAD.
- —**Discreet, insured packaging** and Canadian support that answers.
Frequently asked questions
What is tirzepatide?
Tirzepatide, listed here as GLP-2/Tirz, is a synthetic dual agonist of the GIP and GLP-1 receptors. As a pharmaceutical it is sold as Mounjaro and Zepbound. The material supplied here is research-grade, for in vitro laboratory use only, and is not the approved pharmaceutical product.
How much weight loss did tirzepatide produce in trials?
In SURMOUNT-1 (NEJM, June 4, 2022), participants on 15 mg showed a mean 22.5% reduction in body weight at 72 weeks — about 52 lb (24 kg) — versus 2.4% for placebo. In adults with type 2 diabetes (SURMOUNT-2), the figure was 15.7% at 15 mg.
Is tirzepatide better than semaglutide?
In the first head-to-head trial, SURMOUNT-5, tirzepatide produced 20.2% mean weight reduction versus 13.7% for semaglutide over 72 weeks in 751 participants (p<0.001), with a greater reduction in waist circumference. Unlike cross-trial comparisons, this was a direct comparison under one protocol.
Is tirzepatide approved in Canada?
Yes, as a prescription medicine. Mounjaro has been approved for type 2 diabetes since 2022, Zepbound for weight management since May 2025, and Zepbound for obstructive sleep apnea in adults with obesity since June 11, 2026. Research-grade material is not the approved product and is not a substitute for it.
How does tirzepatide compare to retatrutide?
Tirzepatide is a dual agonist with a peak trial reduction of 22.5%; retatrutide is a triple agonist reaching 28.3% in TRIUMPH-1. Tirzepatide is approved and has a published head-to-head win; retatrutide is unapproved and still in Phase 3.
Can I buy tirzepatide in Canada?
GLP-2/Tirz is available from Popular Peptides for laboratory research use, shipped domestically from Vancouver with a third-party certificate of analysis verifiable by lot number. It is not the approved pharmaceutical, is not approved for therapeutic use, and is not sold for human or veterinary consumption.
How much does tirzepatide cost in Canada?
GLP-2/Tirz is supplied as a single lyophilised 10 mg vial, lot-tested, with the current per-vial price shown on the GLP-2/Tirz product page. It ships domestically from Vancouver, so there is no customs step and no import brokerage fee. Research-grade material is not the approved pharmaceutical product and is supplied for laboratory research use only.
Sources
- —Jastreboff AM et al., Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1), New England Journal of Medicine, June 4, 2022
- —Aronne LJ et al., SURMOUNT-5, New England Journal of Medicine, 2025;393(1):26-36
- —Garvey WT et al., SURMOUNT-2, The Lancet, 2023
- —Health Canada authorisation of Zepbound for obstructive sleep apnea, June 11, 2026
- —Wilding JPH et al., Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP-1), New England Journal of Medicine, 2021
GLP-2/Tirz is supplied for in vitro laboratory research use only. It is not the approved pharmaceutical product, is not approved by Health Canada for therapeutic use, and is not intended for human or veterinary consumption. 18+.
Every batch we sell is independently third-party tested, with the full Certificate of Analysis published and checkable by lot number.