Tirzepatide
Tirzepatide is a single engineered peptide that activates both the GIP and GLP-1 receptors, FDA-approved as Mounjaro for type 2 diabetes and Zepbound for chronic weight management.
Regulatory status: FDA-approved: Mounjaro for type 2 diabetes and Zepbound for chronic weight management, with a later approval covering moderate-to-severe obstructive sleep apnoea with obesity. The approved label for the specific product and indication governs use.
Default vial
30 mg
Default mix
2 mL
Reported range
2.5 → 15 mg
Draw (U-100)
16.7 u
Dual GIP/GLP-1 agonist; weekly with a 4-week titration ladder.
What it is
- A dual GIP/GLP-1 receptor co-agonist — one 39-amino-acid peptide engineered to bind both receptors.
- Described in the literature as a unimolecular dual incretin agonist.
- Given once weekly by subcutaneous injection, titrated to 5, 10 or 15 mg in the pivotal trials.
- Subcutaneous injection only; no oral formulation is approved.
How it is described to act
- 1
Administered subcutaneously, with slow absorption and a long circulating half-life that supports weekly dosing.
- 2
Reported to reach tissues expressing GIP and GLP-1 receptors, including pancreatic islets, adipose tissue and central feeding centres.
- 3
Acts at both receptors at once — a mechanism proposed to give additive metabolic effects compared with GLP-1 agonism alone.
- 4
In trial cohorts this was associated with substantial reductions in body weight and HbA1c, alongside gastrointestinal effects during titration.
What the research has looked at
Obesity (SURMOUNT programme)
- In SURMOUNT-1 (NEJM, 2022), Jastreboff et al. reported that participants on the 15 mg dose lost significantly more weight than placebo over 72 weeks.
Glycaemic control (SURPASS programme)
- The approved Mounjaro label cites the SURPASS trials, reporting HbA1c reductions versus placebo and against active comparators including semaglutide and insulin degludec.
Strength of evidence: Approved drug (for a specific indication)
Supported by multiple completed phase 3 randomised trials and current FDA approval for specific indications.
This molecule is an approved medicine for at least one indication. Where that is the case, the approved prescribing information — not community convention — governs its use.
Reported cautions and unknowns
- Nausea, diarrhoea and vomiting were the most frequent adverse events in SURMOUNT-1, particularly during dose escalation.
- The label carries a boxed warning about thyroid C-cell tumours seen in rodents, with the same medullary thyroid carcinoma and MEN2 contraindication as the GLP-1 class.
- Acute pancreatitis and gallbladder events such as cholelithiasis and cholecystitis are listed as label warnings.
- The label states it is not recommended in pregnancy, based on animal developmental toxicity data.
References
Handling this vial
- Lyophilized vials are generally stored at 2–8 °C and kept out of light; once reconstituted with bacteriostatic water they are refrigerated and commonly discarded after 28 days.
- Mix by aiming water down the vial wall and rolling gently — do not shake — and never re-freeze a reconstituted vial.
- Pep-Tidy cannot verify what is in your vial. Ask your supplier for a current Certificate of Analysis (HPLC/MS).
Tirzepatide questions people ask
How do you reconstitute Tirzepatide?
A common starting point for a 30 mg vial of Tirzepatide is 2 mL of bacteriostatic water, which gives 15 mg per mL. Aim the water down the inside wall of the vial, let it dissolve on its own, and roll gently instead of shaking. Pep-Tidy's reconstitution calculator will recalculate the numbers for any other vial size or water volume you use.
How many units of Tirzepatide is one dose?
At 15 mg per mL, that works out to about 16.7 units on a U-100 insulin syringe for a 2500 mcg dose. Change the vial size, water volume, or target dose in the calculator and the syringe reading updates with it. This is arithmetic, not a dosing recommendation.
What dosing schedule is reported for Tirzepatide?
Published and community sources describe 2.5 → 15 mg, subcutaneous, once weekly, typically run 20 weeks on. These figures describe what has been reported, not what anyone should take — talk to a licensed clinician first.
How should Tirzepatide be stored?
Lyophilized Tirzepatide vials are generally kept at 2–8 °C and out of light. Once reconstituted with bacteriostatic water they are refrigerated and commonly discarded after about 28 days. Never re-freeze a reconstituted vial and never shake it.
Read this before you act on anything above
Everything on this page is a summary of what other people have published — it is not medical advice, not a recommendation, and not a dosing instruction. Reported dose ranges describe what appears in the literature or in community protocols, not what anyone should take. Talk to a licensed clinician before using any peptide.