Tirzepatide (sold as Mounjaro for type 2 diabetes and Zepbound for weight loss) is available as a lyophilized research peptide that must be reconstituted with bacteriostatic water before use. Getting the concentration right is critical because tirzepatide is typically dosed in milligrams, not micrograms, so small errors in the draw amount have a larger relative impact.
What You Need
- Tirzepatide vial (common research sizes: 2 mg, 5 mg, 10 mg, 15 mg)
- Bacteriostatic water (BAC water) for injection
- Insulin syringes, U-100 scale (0.3 mL or 0.5 mL)
- Alcohol swabs
- Refrigerator (36-46°F / 2-8°C) for storage
Choosing Your BAC Water Volume
The amount of BAC water you add determines the final concentration of your solution. A common target is 1 mg/mL, which keeps the math simple. For tirzepatide, a slightly higher concentration (2 mg/mL or 5 mg/mL) may be useful if your starting dose is 2.5 mg or higher, since it reduces injection volume.
Enter your vial size and BAC water volume into the PeptiTools tirzepatide calculator. It will show the resulting concentration and the exact number of syringe units to draw for any dose, with no manual math required.
- 5 mg vial + 5 mL BAC water = 1 mg/mL (25 units per 0.25 mg dose)
- 5 mg vial + 2.5 mL BAC water = 2 mg/mL (12.5 units per 0.25 mg dose)
- 10 mg vial + 2 mL BAC water = 5 mg/mL (10 units per 0.5 mg dose)
- 15 mg vial + 3 mL BAC water = 5 mg/mL (15 units per 0.75 mg dose)
Step-by-Step Reconstitution
- Wipe the top of both the tirzepatide vial and BAC water vial with an alcohol swab. Let them air dry for 15 seconds.
- Draw your chosen volume of BAC water into the syringe.
- Insert the needle into the tirzepatide vial at a 45-degree angle.
- Inject the BAC water slowly along the inner glass wall of the vial, not directly onto the powder.
- Gently swirl the vial (never shake) until the powder fully dissolves.
- The resulting solution should be clear and colorless. Discard if you see any cloudiness, color change, or floating particles.
- Label the vial with the date reconstituted and the concentration (e.g., "2 mg/mL").
Tirzepatide Starting Doses and Titration
Clinical protocols for tirzepatide typically start at 2.5 mg per week and titrate upward every 4 weeks as tolerated. Research peptide protocols often mirror this approach to minimize gastrointestinal side effects during the initial period.
- Weeks 1-4: 2.5 mg per week
- Weeks 5-8: 5 mg per week
- Weeks 9-12: 7.5 mg per week
- Weeks 13-16: 10 mg per week (if tolerated)
- Weeks 17+: 12.5 mg or 15 mg per week (maximum)
Using the PeptiTools Calculator for Tirzepatide
Open the PeptiTools tirzepatide calculator and enter three values: your vial size in milligrams, how much BAC water you added in milliliters, and your desired dose. The calculator converts your dose from milligrams to the exact number of units to draw on a U-100 insulin syringe, with a live diagram showing where to stop.
Example: 5 mg vial, 2.5 mL BAC water, 2.5 mg dose. Concentration = 2 mg/mL. Draw = 1.25 mL. On a U-100 syringe: 125 units. That exceeds a 0.5 mL syringe capacity, so with this concentration you would split into two injections, or reduce concentration to 1 mg/mL and draw 62.5 units.
Tirzepatide vs Semaglutide: Reconstitution Differences
Both tirzepatide and semaglutide are reconstituted the same way, but their typical dose ranges differ significantly. Semaglutide research doses commonly start at 0.25 mg/week (250 mcg), while tirzepatide starts at 2.5 mg/week, which is 10 times higher. This means tirzepatide draws are larger in volume for an equivalent concentration, and many users prefer a higher concentration (2-5 mg/mL) to keep injection volumes manageable.
Storage and Shelf Life
Reconstituted tirzepatide should be refrigerated immediately after mixing and stored at 2-8°C (36-46°F). It remains stable for up to 28 days when properly refrigerated. Avoid freezing reconstituted peptides, as freeze-thaw cycles degrade the peptide chain. Lyophilized (unmixed) tirzepatide powder can be stored at -20°C for longer periods.