Tirzepatide (Mounjaro / Zepbound)
Tirzepatide acts like two gut satiety hormones at once. It is studied for weight loss and type 2 diabetes; in studies, weight loss reached 22.5%, almost as much as after stomach surgery.
39 amino acids, a dual GLP-1/GIP agonist based on GIP with an optimized affinity balance. C20 fatty acid. ~4813 Da.
SURMOUNT-1 (n=2539): −22.5% over 72 weeks — the first drug comparable to bariatric surgery. 96% of participants lost ≥5%. The best efficacy/tolerability ratio among approved drugs as of 2025.
GIP-R agonism: ↑β-cell function, ↑peripheral tissue insulin sensitivity, ↑brown adipose tissue thermogenesis, ↑β-oxidation. GLP-1R agonism: ↓appetite, ↓glucagon, ↑satiation. The synergy of the two systems reduces insulin resistance more than either component alone.
Studies used the TIRZAPLUS titration schedule: weeks 1–4 — 2.5 mg/week; weeks 5–8 — 5.0 mg; weeks 9–12 — 7.5 mg; weeks 13–20 — 10.0 mg; weeks 21+ — 12.5–15.0 mg (if tolerated). Administration once weekly SC.
Level A Human clinical trials. There are randomized controlled trials (RCTs), or the compound has been approved by a regulatory agency. The most reliable level. FDA-approved (Mounjaro 2022, Zepbound 2023). More potent than semaglutide for weight loss.
Honest caveat: Long-term safety data (>3 years) are limited vs 7 years for semaglutide. In T2D + insulin — risk of hypoglycemia. SURMOUNT-4: weight returns after discontinuation.
Research peptides are laboratory reagents (Research Use Only). They are not medicines and are not intended for use in humans or animals.