What is Tirzepatide?

Tirzepatide is one peptide built to act on two receptors. GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) are hormones your gut produces after a meal; they bind receptors in the pancreas, the brain and elsewhere, increase the insulin the pancreas releases in response to food, and reduce appetite European Medicines Agency. Mounjaro (tirzepatide): European public assessment report.. Earlier compounds in this class act on the GLP-1 receptor alone. Tirzepatide was engineered as a fatty-acid-modified peptide that activates both GIP and GLP-1 receptor signalling: in its discovery paper it produced glucose-dependent insulin secretion in mice, reduced body weight and food intake in mice by more than a GLP-1-only agonist did, and in its Phase 1 study, 142 people across all arms, the most frequent side effects were gastrointestinal and dose-dependent 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. Mol Metab 2018. PMID 30473097. Where that second receptor places tirzepatide among the single-, dual- and triple-receptor compounds is set out at incretin peptides.

The weight evidence comes from the SURMOUNT programme. SURMOUNT-1 was a 72-week, double-blind, placebo-controlled Phase 3 trial in 2,539 adults who had obesity, or overweight with at least one weight-related complication, and did not have diabetes. It tested three strengths of tirzepatide, 5 mg, 10 mg and 15 mg, against placebo. At week 72, mean weight had changed by −15.0%, −19.5% and −20.9% on the three strengths against −3.1% on placebo; 85%, 89% and 91% of participants on tirzepatide had lost at least 5% of their body weight against 35% on placebo; the commonest adverse events were gastrointestinal, mostly mild to moderate and mainly during the trial's dose-escalation period, and they led 4.3% to 7.1% of participants on tirzepatide to stop treatment against 2.6% on placebo Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med 2022. PMID 35658024.

The diabetes evidence comes from SURPASS, and its head-to-head against semaglutide, the GLP-1-only comparator, is the trial most people ask about. SURPASS-2 was an open-label, 40-week Phase 3 trial in 1,879 patients with type 2 diabetes that compared the same three strengths of tirzepatide with semaglutide 1 mg: glycated haemoglobin fell by 2.01, 2.24 and 2.30 percentage points on tirzepatide against 1.86 on semaglutide, tirzepatide was noninferior and superior at every strength, weight fell by a further 1.9 to 5.5 kg, and the commonest adverse events in both groups were gastrointestinal Frías JP et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med 2021. PMID 34170647. In obesity without diabetes, SURMOUNT-5 randomised 751 adults to the maximum tolerated dose of either compound for 72 weeks and reported −20.2% with tirzepatide against −13.7% with semaglutide Aronne LJ et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. N Engl J Med 2025. PMID 40353578. Both comparisons were open-label, one of the things to keep in view when reading tirzepatide vs semaglutide.

Tirzepatide is an authorised medicine in the European Union. The authorisation was granted as Mounjaro on 15 September 2022 and covers type 2 diabetes and, in adults, weight management; the EU has no second brand for the weight indication European Medicines Agency. Mounjaro (tirzepatide): European public assessment report.. Our 60 mg pen is not Mounjaro. It contains the same active molecule and holds no marketing authorisation: it comes without the approved dosing information, the product-characteristics summary, the pharmacist and the adverse-event surveillance that surround the authorised product, and the trial results above describe the molecule as it was given in those trials, not this pen. We set out why every compound in our range sits outside the authorised route at why these compounds are not EMA-authorised.

The compound most often set against tirzepatide is retatrutide, which adds a third receptor, glucagon, to the same GIP and GLP-1 pair. Its published human evidence is a 48-week, placebo-controlled Phase 2 trial in 338 adults with obesity: weight fell by a mean 24.2% at the highest strength against 2.1% on placebo, the gastrointestinal side effects rose with dose, and heart rate rose in a dose-dependent way to a peak at 24 weeks before declining Jastreboff AM et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med 2023. PMID 37366315. A Phase 2 figure and a Phase 3 figure from different trials are not the same kind of number, and the two compounds have never been compared head-to-head; we lay that out at retatrutide vs tirzepatide. We stock the triple agonist as RETATRUTIDE 32 and RETATRUTIDE 64, one compound at two strengths, 32 mg or 64 mg per 3 ml pen.

What we supply is TIRZEPATIDE 60: 60 mg of tirzepatide already in solution in a 3 ml pre-loaded multi-dose pen, currently on pre-order. Every batch is tested by an independent lab for identity (mass spectrometry), purity (HPLC) and sterility, and the certificate for your batch shows the HPLC purity figure and the concentration of the cartridge (mg/ml and total mg per 3 ml); reach it by scanning the QR code on the pen or from the index at /coa. The pen is also listed with our NAD+ pen as the Lean Stack: two products sold together, nothing mixed, and no guidance from us on combining them.