Peptides
Tirzepatide
GIP/GLP-1 Dual Receptor Agonist
Category
Dual agonist (GLP-1)
Half-life
~5 days
Typical dose
2.5mg → 15mg (escalating)
Frequency
Once weekly
Route
Subcutaneous injection
Mechanism
Tirzepatide is a dual agonist targeting GIP and GLP-1 receptors. GLP-1 receptor activation suppresses appetite, slows gastric emptying, and stimulates insulin secretion. GIP receptor activation enhances insulin sensitivity and contributes to additional weight loss beyond GLP-1 alone. FDA approved as Mounjaro (diabetes) and Zepbound (obesity).
Research summary
SURMOUNT-1: 22.5% mean weight loss at 72 weeks in patients without diabetes. SURMOUNT-2: 15.7% weight loss in patients with type 2 diabetes. Currently the most prescribed GLP-1 class drug for weight loss in the US. Well-established side effect profile: nausea, vomiting, diarrhea most common, typically resolving after the escalation phase.
Storage
Refrigerate at 2–8°C. Do not freeze.
Key studies
Jastreboff AM, et al. (2022). Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). NEJM. DOI: 10.1056/NEJMoa2206038
Garvey WT, et al. (2023). Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2). Lancet. DOI: 10.1016/S0140-6736(23)01554-3
Frequently asked questions
What is the tirzepatide starting dose?
The SURMOUNT protocol starts at 2.5mg once weekly for 4 weeks, then escalates by 2.5mg every 4 weeks as tolerated, up to a maximum of 15mg weekly.
How much weight loss does tirzepatide cause?
SURMOUNT-1 showed 22.5% mean body weight reduction at 72 weeks in non-diabetic patients. Results vary by dose and individual response.
What are tirzepatide side effects?
Most common: nausea, diarrhea, vomiting, constipation — typically during dose escalation and resolving at maintenance dose. Rare: pancreatitis, gallbladder disease. Contraindicated in personal or family history of medullary thyroid cancer.
For research use only. Not intended for human consumption. Not medical advice. Consult a licensed physician before use.