Tirzepatide: Dual GLP-1 / GIP Agonist

What Tirzepatide is

Tirzepatide is a dual agonist of the GIP and GLP-1 receptors, the first of its class approved by the FDA (Mounjaro™ for type 2 diabetes; Zepbound™ for obesity). It is a synthetic 39-amino-acid peptide with a C20 fatty acid chain that extends its half-life to ~5 days, allowing weekly dosing.

Dual mechanism: GIP + GLP-1

Unlike semaglutide (GLP-1 only), tirzepatide activates two incretins at once:

• GLP-1 — slows gastric emptying, increases satiety and enhances glucose-dependent insulin secretion.
• GIP — amplifies the insulin response and, according to the evidence, improves lipid handling and sensitivity in adipose tissue.

In clinical trials, the combination showed greater weight loss and better glycemic control than GLP-1 agonism alone.

Published studies

SURPASS (type 2 diabetes)

The SURPASS program (NEJM, 2021) showed HbA1c reductions superior to semaglutide 1 mg and to basal insulin, with dose-dependent weight loss.

SURMOUNT (obesity)

SURMOUNT-1 (NEJM, 2022): in adults with obesity without diabetes, the 15 mg dose achieved ~21% average body weight reduction at 72 weeks — among the largest reported for a pharmacological agent.

Dose ranges in research

Published protocols use titration: starting at 2.5 mg/week SC, escalating every 4 weeks (2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg) to minimize gastrointestinal effects. Descriptive context from the literature, not a clinical recommendation.

Our ready-to-use and powder vials cover 10 mg to 60 mg.

Reconstitution

For the powder vial, reconstitute with bacteriostatic water according to the target concentration. Formulas and U100 examples in the reconstitution guide.

Stacks in research

• MOTS-c — to support mitochondrial function and preserve lean mass during the deficit.
• Retatrutide — compared, not combined; see the technical comparison.