What is tirzepatide?

What is tirzepatide?

Tirzepatide is a peptide dual agonist of the GIP and GLP-1 receptors, supplied for research purposes in a pre-filled multi-dose pen.

It is one of the most studied incretin peptides in weight-loss and metabolism research, adding a GIP arm to the GLP-1 mechanism. Research results vary with dose and duration.

Mechanism of action

Tirzepatide is a 39-amino-acid peptide, acylated to bind albumin, that activates the GIP and GLP-1 receptors with a single molecule. Its half-life of around five days allows weekly administration. The GLP-1 arm provides the satiety, delayed gastric emptying and glucose-dependent insulin secretion known from semaglutide.

The GIP arm is what distinguishes it. GIP acts on adipose tissue and on central appetite signalling, and in the comparative trials dual agonism produced more weight loss and better glycaemic control than a GLP-1 agonist alone at the doses studied, with similar gastrointestinal tolerance.

The published titration climbs in 2.5 mg steps every four weeks to a maximum of 15 mg weekly. The steps exist to let the digestive tract adapt; in the trials, most of the nausea was concentrated in the step-up weeks.

What the published research says

1. 1.
   Jastreboff et al., N Engl J Med, 2022 (SURMOUNT-1)PMID 35658024

   2,539 adults with obesity, 72 weeks. Mean weight reduction of 15.0%, 19.5% and 20.9% with 5, 10 and 15 mg weekly against 3.1% with placebo.

2. 2.
   Frías et al., N Engl J Med, 2021 (SURPASS-2)PMID 34170647

   Head-to-head comparison with semaglutide 1 mg in type 2 diabetes over 40 weeks: tirzepatide reduced HbA1c and weight more at all three doses, with a comparable gastrointestinal adverse-effect profile.

3. 3.
   Wilding et al., N Engl J Med, 2021 (semaglutide, reference)PMID 33567185

   STEP 1: 14.9% weight loss with semaglutide 2.4 mg at 68 weeks. It is the single-receptor reference against which the tirzepatide data are read.

What side effects does tirzepatide have?

• Nausea and appetite suppression: the most reported effects, generally dose-dependent.
• Other gastrointestinal effects (fullness, changes in bowel habit) at higher doses.
• Mild, transient injection-site reactions.

How is tirzepatide dosed?

It is dosed once a week with a stepped climb: a common research scheme is 2.5 → 5 → 7.5 → 10 → up to 15 mg, stepping up every four weeks. Each step is set precisely on the pen.

Storing the pen

Keep the pen between 2 and 8 °C, protected from light and never frozen. Unopened it has a 24-month shelf life; from the first puncture, 12 months. If no fridge is available it keeps for up to 30 days at room temperature, below 30 °C. Let it reach room temperature before giving a dose. The dial sets each dose directly in milligrams: there is no reconstitution, no bacteriostatic water and no volume calculation.

How do you get tirzepatide?

Body Pharm's tirzepatide pen is a sealed, HPLC-verified device with a published certificate of analysis (CoA). Shipping is to Spain only: a single option at €15, delivered in 3–5 working days. It is sold exclusively for research purposes.

How much does tirzepatide cost per month?

Announced on release: reserve it free on the waitlist, nothing is charged.

How it compares

Tirzepatide sits in the middle of the family: more weight loss than semaglutide in the comparative trials, but without retatrutide's glucagon arm. It is by far the compound of the three with the most published human data after semaglutide, including 72-week trials and head-to-head comparisons.

For research, the detail that usually decides between tirzepatide and retatrutide is the maturity of the evidence: tirzepatide holds marketing authorisation as a medicine in several jurisdictions and has a well-characterised titration; retatrutide has had phase 3 results published since 2026, but remains unauthorised.

• Retatrutide vs semaglutide vs tirzepatide
• What is retatrutide?
• What is semaglutide?