Tirzepatide
The dual GIP/GLP-1 agonist behind Mounjaro and Zepbound.
Overview
Tirzepatide is a once-weekly injection that acts on two gut-hormone receptors, GIP and GLP-1. It is FDA-approved as Mounjaro (type 2 diabetes) and Zepbound (chronic weight management and obstructive sleep apnea with obesity). In a head-to-head trial it produced more weight loss than semaglutide.
How it works
A 39-amino-acid peptide with a C20 fatty diacid at lysine-20 that binds albumin, so it lasts about 5 days. GLP-1 and GIP receptor activation lowers appetite, slows stomach emptying, and boosts insulin release when blood sugar is high.
Evidence
5/5
FDA-approved on the basis of large phase 3 programs (SURPASS for diabetes, SURMOUNT for obesity, SURMOUNT-OSA for sleep apnea).
Half-life
About 5 days (once-weekly dosing)
Known as
Mounjaro, Zepbound, LY3298176, AMP-2 (TR)
Compound facts
- Type
- Dual GIP/GLP-1 receptor agonist
- CAS Number
- 2023788-19-2
- Molecular Formula
- C225H348N48O68
- Molecular Weight
- 4810.52 g/mol
- Amino Acids
- 39
- Modification
- C20 fatty diacid at Lys-20
Reported benefits
Weight loss
SURMOUNT-1: about −21% average weight loss at 72 weeks on 15 mg vs about −3% on placebo.
Beat semaglutide head-to-head
SURMOUNT-5: −20.2% vs −13.7% with Wegovy over 72 weeks.
Blood sugar control
Large A1c reductions in type 2 diabetes (SURPASS trials).
Sleep apnea
Cut apnea events by roughly 25–30 per hour at 52 weeks in SURMOUNT-OSA; FDA-approved for this in 2024.
“Anecdotal” means reported by users, not shown in controlled trials.
Community-reported regimens
Not recommendations. These are commonly cited ranges, shown so you can see what real-world use looks like.
| Plan | Dose | Frequency | Duration | Route |
|---|---|---|---|---|
| Label start 2.5 mg is a starting dose to build tolerance, not a treatment dose. Increase by 2.5 mg every 4 weeks as tolerated. | 2500 mcg | Once weekly | 4 weeks | Subcutaneous (abdomen, thigh, upper arm) |
| Label maintenance (low) Approved maintenance doses are 5, 10 or 15 mg. | 5000 mcg | Once weekly | Ongoing | Subcutaneous |
| Label maximum Reached only after stepping up through 5, 7.5, 10 and 12.5 mg. | 15000 mcg | Once weekly | Ongoing | Subcutaneous |
Reconstitution calculator
Set up for Tirzepatide. Switch peptide or vial size any time.
1Mix
Add 2 mL water for 15 mg/mL
2Draw
Draw to 16.7 units = 0.167 mL = 2.5 mg
Drag the plunger to set your dose.
3Inject
Next site
Right belly, upper
Tap a site after you inject to keep a rotation.
Pinch the skin, stay 2 in. from the navel, then into a sharps bin.
- Doses per vial
- 12
- Vial lasts
- 84 days
- Good once mixed
- ~28 days
- Syringe
- 30-unit, 0.3 mL
The vial outlasts its ~28-day shelf life once mixed. A smaller vial wastes less.
Math only: concentration (mg/mL) = vial mg ÷ mL of water; units = dose (mg) ÷ concentration × 100. Always double-check against your own vial label and a clinician. This tool does not recommend a dose.
Reconstitution
Diluent: Bacteriostatic water (0.9% benzyl alcohol) — allows multiple draws from one vial.
- Wipe both vial tops with an alcohol swab and let dry.
- Draw the diluent, then inject it slowly down the inside wall of the vial — never straight onto the powder.
- Swirl gently or let it sit; do not shake. Foam can damage peptides.
- Solution should be clear. Cloudy, stringy or discolored = discard.
- Large vials last many weeks at low doses; check you will use it within the storage window.
- Common mix: 30 mg + 3 mL = 10 mg/mL (2.5 mg = 25 units).
Storage
Powder
Freezer / fridge
Keep sealed vial in the freezer (−20 °C) for long-term storage; fridge (2–8 °C) is fine for a few weeks. Keep dry and out of light.
After mixing
~28 days
Refrigerate at 2–8 °C. Never freeze after mixing. Keep upright, capped, and out of light.
Travel
Keep cool
Short trips at room temperature are generally fine for powder; keep mixed vials cold.
- Branded pens have their own storage rules; these notes apply to powder vials only.
Side effects & cautions
Reported side effects
- Nausea, diarrhea, vomiting, constipation (most common, worst during dose increases)
- Reduced appetite, indigestion, belly pain
- Injection-site reactions
- Fatigue
- Hair thinning reported with rapid weight loss
Cautions
- Boxed warning class: GLP-1 drugs caused thyroid C-cell tumors in rodents. Do not use with a personal or family history of medullary thyroid cancer or MEN2.
- Pancreatitis has been reported. Severe, persistent belly pain that may spread to the back needs urgent care.
- Gallbladder problems (gallstones) are more common, especially with fast weight loss.
- Do not combine with another GLP-1 drug (semaglutide, tirzepatide, retatrutide, etc.).
- Raises low-blood-sugar risk when combined with insulin or sulfonylureas.
- Not for use in pregnancy; stop well before trying to conceive. Slowed stomach emptying can matter before surgery or sedation.
- Can reduce how well oral birth control works, especially after starting or raising the dose; the label advises a backup method.
FDA & international status
FDA-approved (Mounjaro 2022, Zepbound 2023)
Mounjaro is approved for type 2 diabetes; Zepbound for chronic weight management and moderate-to-severe obstructive sleep apnea in adults with obesity. The FDA declared the tirzepatide shortage over in late 2024, and enforcement discretion for compounding ended in early 2025. Research vials are not the approved drug.
Regulations change often — verify with the FDA, EMA, MHRA, Health Canada, TGA and WADA before acting.
Where to buy
| Size | Price | Per mg | Stock | Latest COA |
|---|---|---|---|---|
| 30 mg | $59.99 | $2.00 | Out of stock | 99.76% pure, lot TRZ0001 ILS Labs, tested 2026-08-03 |
| 60 mg | $109.99 | $1.83 | In stock | 99.35% pure, lot TRZ0002 ILS Labs, tested 2026-08-03 |
Amino Club list prices as of 2026-10-07, before promo codes. Multi-buy: 2+ units 5% off, 3+ units 7.5% off, 10+ units 40% off. Prices change; confirm on the product page. Mixing? Their bacteriostatic water is Amino H2O from $19.99.
Tirzepatide at Amino Club
Check sizes, current price and the certificate of analysis (COA) on the product page. Sold for in-vitro research only.
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- Look for a batch-specific COA with HPLC purity (≥98%) and mass-spec identity.
- Typical vial sizes: 30, 60 mg.
FAQ
Is a research vial the same as Zepbound?
No. The compound may be the same, but research vials have no regulated manufacturing, sterility or dose checks.
Why start at 2.5 mg if it barely works?
The starting dose is for tolerance. Most GI side effects show up during dose increases, so the label goes up 2.5 mg at a time every 4 weeks.
What if I miss a dose?
The label says take it within 4 days of the missed dose; if more than 4 days have passed, skip it and resume your usual day.