In the Kirei Clinic catalog these are two products and two certificates. Semaglutide batch PP06115 reported 5.01 mg at 99.367% purity. Tirzepatide batch TQ21884 reported 10.41 mg at 99.115% purity. Do not use one report for the other vial. Product pages: semaglutide and tirzepatide. Research use only.
The GLP-1 receptor agonist class has reshaped metabolic medicine over the past decade. Semaglutide — commercialised as Ozempic and Wegovy — established a new benchmark for non-surgical weight loss. Tirzepatide, a dual GIP/GLP-1 agonist, has since demonstrated superior efficacy in several head-to-head and comparative analyses. Understanding why requires a look at their distinct mechanisms.
GLP-1 Receptor Agonism: The Shared Core
Both compounds target the glucagon-like peptide-1 receptor, a class B G-protein-coupled receptor expressed in the pancreatic beta cells, hypothalamus, vagal nerve afferents, and gut. GLP-1R activation drives glucose-dependent insulin secretion, suppresses glucagon release, delays gastric emptying, and induces satiety via central and peripheral pathways. These overlapping effects explain the class-wide efficacy in type 2 diabetes and obesity.
What Makes Tirzepatide Different
Tirzepatide adds agonism at the glucose-dependent insulinotropic polypeptide (GIP) receptor. GIP was historically underestimated as a therapeutic target because GIP receptor agonism alone shows limited metabolic benefit in humans with established obesity. However, the combination with GLP-1R agonism appears synergistic.
The proposed mechanism involves GIP receptor signalling in adipose tissue, which may improve lipid storage dynamics and reduce ectopic fat deposition. Rodent studies have also suggested GIP/GLP-1 co-agonism produces additive effects on hypothalamic satiety centres beyond what either pathway achieves alone.
Clinical Trial Outcomes
The SURMOUNT-1 trial (tirzepatide) reported mean body weight reductions of 20.9% at the highest dose (15 mg weekly) over 72 weeks in adults with obesity without diabetes. The STEP-1 trial (semaglutide 2.4 mg weekly) reported a mean reduction of 14.9% over 68 weeks in a comparable population.
Across both trials, responder rates were high, but tirzepatide's greater weight loss depth translated into higher proportions of patients achieving ≥20% and ≥25% body weight reduction milestones. Notably, adverse event profiles were similar — predominantly nausea, vomiting, and diarrhoea — with dose-escalation protocols mitigating most of these.
Cardiovascular Data
Semaglutide has a longer established cardiovascular outcomes record. The SUSTAIN-6 and LEADER trials (liraglutide) demonstrated MACE reduction. The SELECT trial (2023) showed semaglutide 2.4 mg reduced major adverse cardiovascular events by 20% in non-diabetic adults with obesity and prior cardiovascular disease. Tirzepatide's cardiovascular outcomes trial (SURPASS-CVOT) is ongoing and expected to report in 2026.
Research Compound Context
Both semaglutide and tirzepatide are available as regulated pharmaceutical products in many countries. Research-grade peptide analogues are used in preclinical and investigational contexts. Purity and stability standards differ significantly between pharmaceutical and research-grade material; HPLC verification is essential for any research application.
Summary
- Semaglutide: selective GLP-1R agonist; ~14–17% mean weight loss in trials
- Tirzepatide: dual GIP/GLP-1R agonist; ~20–21% mean weight loss at max dose
- Both show similar GI adverse event profiles; tirzepatide's superiority is dose-dependent
- Cardiovascular outcomes data more mature for semaglutide class
This article summarises published research for educational purposes. These compounds require medical supervision. They are not available for human use outside approved pharmaceutical channels.