Tirzepatide
Tirzepatide is a dual GIP and GLP-1 receptor agonist. The FDA approved it on 13 May 2022.
Checked by the PU Research editorial team — evidence-graded against primary sources. Last check: 23 July 2026. Sources: 2. Who checks this
01Identity & Classification
Tirzepatide is a dual GIP and GLP-1 receptor agonist. The brand name Mounjaro covers diabetes. The brand name Zepbound covers obesity and obstructive sleep apnea. The FDA approved it on 13 May 2022 under NDA 215866.
02Mechanism: How It Works
Tirzepatide binds and activates two receptors: the GIP receptor and the GLP-1 receptor.
It increases first-phase and second-phase insulin secretion. It decreases glucagon. Both effects depend on the glucose level. It slows gastric emptying.
The molecule carries a C20 fatty diacid. That group binds albumin.
03Research Findings
Evidence tier: clinical.
SURPASS-2 enrolled 1,879 participants. At 40 weeks, tirzepatide 15 mg decreased HbA1c by 2.37%. Semaglutide 1 mg decreased HbA1c by 1.86%.
Body weight fell 11.2 kg in the tirzepatide 15 mg group. Body weight fell 5.7 kg in the semaglutide comparison group.
04Reported Dosing & Delivery
Source: the FDA label.
- Start at 2.5 mg by subcutaneous injection, once each week.
- Increase to 5 mg after 4 weeks.
- Increase in 2.5 mg steps.
- The maximum adult dose is 15 mg each week.
Six strengths exist, from 2.5 mg to 15 mg. A prescriber controls the schedule.
05Pharmacokinetics & Timing
Albumin binding makes the half-life long. One dose each week is enough. The label permits any time of day, with or without a meal.
06Interactions & Combinations
Tirzepatide can decrease the effect of an oral hormonal contraceptive. Delayed gastric emptying causes this. The effect is largest after the first dose.
The label tells patients to use a non-oral method or a barrier method for 4 weeks after the start and after each dose increase.
The risk of low blood glucose increases with insulin or with a sulfonylurea.
Compare with Semaglutide and Retatrutide.
07Safety & Contraindications
Boxed warning. Tirzepatide causes thyroid C-cell tumors in rats.
The label lists a contraindication for a history of medullary thyroid carcinoma (MTC). The label lists the same contraindication for multiple endocrine neoplasia syndrome type 2 (MEN 2).
Documented adverse events are pancreatitis, low blood glucose, acute kidney injury, hypersensitivity, gastrointestinal events, and gallbladder disease.
08Monitoring & Biomarkers
- HbA1c and glucose.
- A gallbladder study, if a clinician suspects cholelithiasis.
09Regulatory Status
The FDA approves tirzepatide. The EMA approves tirzepatide. WADA does not prohibit it.
See the regulatory tracker for the 503B bulks list proposal of 30 April 2026.
10Works Cited
- 01FDA Prescribing Information, Mounjaro (NDA 215866). accessdata.fda.gov. View source →
- 02SURPASS-2 results, New England Journal of Medicine, as summarized in the FDA label documentation. View source →
More in Metabolic & Body Composition
Open the Metabolic category →Semaglutide
Semaglutide is a GLP-1 receptor agonist. The FDA approves it for type 2 diabetes and for chronic weight management.
Retatrutide
Retatrutide is an investigational triple receptor agonist. No regulator approves it. Phase 3 work continues.
AOD-9604
AOD-9604 is a modified growth hormone fragment. Six human trials ran. The Phase 2B trial failed its endpoint.
Research use only. This is not medical advice.
PeptideUnlock gives education. Nothing here diagnoses a condition. Nothing here recommends a compound or a dose.
Most peptides on this site have no approval for human use in any country. Some carry documented harms. Several are prohibited in sport.
Regulatory status changes by country and by month. Check the current rule where you live. Speak to a licensed clinician before any health decision.