Tirzepatide
Dual GIP and GLP-1 receptor agonist (âtwincretinâ) for weight loss and glycemic control.
ClinicalPrescription drug (FDA-approved)InjectableMetabolic
Key facts
Common routesSubcutaneous
Half-life~5 days
Typical range2.5-15 mg/week
Résumé
Tirzepatide is the first dual GIP/GLP-1 receptor agonist on the market - sold as Mounjaro (type 2 diabetes) and Zepbound (obesity). In Phase 3 trials (SURMOUNT, SURPASS) it produces the largest weight-loss and HbA1c reductions of any currently available incretin drug and beats semaglutide head-to-head.
The added GIP mechanism amplifies satiety and insulin sensitivity and appears to blunt some of the nausea typical of pure GLP-1 agonists. A meaningful side-effect profile - mostly GI - still applies.
Notes sur le mécanisme
GLP-1 receptor activation
Drives glucose-dependent insulin secretion, suppresses glucagon, and slows gastric emptying. Does most of the work on satiety and central appetite.
GIP receptor activation
Synergizes with GLP-1 on insulin sensitivity and lipid metabolism, and appears to partially offset GLP-1-induced nausea - the defining pharmacological feature of tirzepatide.
Schémas de dosage
Standard titration
Start at 2.5 mg/week for 4 weeks, then step up by 2.5 mg every 4 weeks. Maintenance is typically 5, 10, or 15 mg/week depending on response and tolerance. Don't rush; most users stay on the lowest effective dose as long as it keeps working.
Split dosing (community optimization)
Some users split the weekly dose into two injections (e.g. Monday/Thursday) to lower peak concentration. This reduces nausea and avoids the end-of-week "hunger rebound," while keeping total exposure constant.
Aperçu des données
The evidence base is extensive: multiple Phase 3 RCTs (SURMOUNT and SURPASS) across thousands of participants. In SURMOUNT-1, the 15 mg arm lost 20.9% of body weight over 72 weeks vs 3.1% on placebo. In SURPASS-2, tirzepatide beat semaglutide on both HbA1c and weight reduction.
Phase 3 trials
SURMOUNT-1: up to 20.9% weight loss over 72 weeks at 15 mg. SURPASS-2: superior to semaglutide 1 mg head-to-head.
Real-world use
Broad clinical adoption confirms trial results. Main limits: cost, supply, and drop-off when titration is rushed.
Considérations de sécurité
Safety leans heavily on slow titration and dietary management (hydration, protein, fiber). GI effects (nausea, constipation) are common and manageable. Thyroid C-cell tumors carry a boxed warning on the label and rule the drug out for anyone with MTC or MEN2 history.
Key cautions
- Charge GI élevée (nausées, constipation, reflux) ; dose-dépendante et sensible à la titration
- Risque de perte musculaire en déficit agressif sans apport protéique élevé ni entraßnement de résistance
- Avertissement encadré pour tumeurs des cellules C thyroïdiennes (données rongeurs) ; contre-indiqué en cas d'antécédents de MTC ou MEN2