How do you reconstitute Tirzepatide?

Draw your chosen volume of bacteriostatic water (1 mL for a 5 mg vial, 2 mL for a 10 mg vial). Inject slowly down the inside wall of the vial, not directly onto the powder. Swirl gently until fully dissolved. Never shake. Refrigerate at 2-8 degrees C immediately and use within 28 days.

How many units do I draw for 2.5 mg of Tirzepatide?

It depends on your reconstitution ratio. With a 10 mg vial and 2 mL BAC water (5 mg/mL): draw to the 50-unit line on a 100-unit insulin syringe. With a 5 mg vial and 1 mL BAC water (5 mg/mL): also draw to the 50-unit line. Use the ASCEND Tirzepatide calculator to confirm any dose and ratio.

What is the Tirzepatide titration schedule?

The standard research titration for Tirzepatide is: 2.5 mg weekly for weeks 1-4, then 5 mg weekly for weeks 5-8, then 7.5 mg weekly for weeks 9-12, then 10 mg for weeks 13-16, then 12.5 mg for weeks 17-20, then 15 mg as the maintenance dose. Each step up occurs every 4 weeks to allow GI tolerance to establish.

How long does a Tirzepatide vial last?

A 10 mg vial at the 2.5 mg starting dose yields 4 weekly doses. At 5 mg weekly it yields 2 doses. At 7.5 mg it yields approximately 1.3 doses. Most researchers start with 10 mg vials at the 2.5 mg dose and titrate up, requiring roughly one new vial per month once at maintenance doses of 10-15 mg.

Dosing Guide May 18, 2026

Tirzepatide Dosing Guide: Reconstitution, Titration, and Exact Syringe Math

Exact syringe draw for every titration step. How to reconstitute a 5 mg or 10 mg vial, which BAC water volume to use, and how to read the unit lines correctly on a 100-unit insulin syringe.

Titration Step	Dose	10 mg/2 mL vial	Draw (units)
Weeks 1-4	2.5 mg	0.5 mL	50 units
Weeks 5-8	5 mg	1.0 mL	100 units
Weeks 9-12	7.5 mg	1.5 mL	150 units*
Weeks 13-16	10 mg	2.0 mL	200 units*
Weeks 17-20	12.5 mg	2.5 mL	250 units*
Maintenance	15 mg	3.0 mL	300 units*

* Draws over 100 units require more than one insulin syringe. Use the ASCEND calculator to confirm exact draws for any vial size and BAC water combination.

Step 1 of 3 · Reconstitution

Choosing the Right BAC Water Volume for Your Vial

Tirzepatide is a 39-amino acid dual GIP/GLP-1 receptor agonist (MW ~4,813 Da) supplied as a lyophilized powder. Before dosing, it must be reconstituted with bacteriostatic water. The BAC water volume you choose sets the concentration and determines every draw volume for the life of that vial.

For a 10 mg vial, 2 mL of BAC water gives 5 mg/mL. This is the most practical ratio: the 2.5 mg starting dose draws to exactly the 50-unit line, and every subsequent titration step scales cleanly. A 5 mg vial with 1 mL BAC water gives the same 5 mg/mL concentration and the same draw table.

Technique: Draw the BAC water into a syringe, then inject it slowly down the inside glass wall of the Tirzepatide vial. Do not aim directly at the powder. Swirl gently until the powder fully dissolves. Never shake, as mechanical agitation can cause peptide aggregation. Refrigerate at 2-8 degrees C immediately.

Open Tirzepatide Calculator →

Step 2 of 3 · Titration

Why the 4-Week Step Interval Is Not Optional

The standard titration is 2.5 mg weekly for four weeks, then a 2.5 mg increase every four weeks up to a maximum of 15 mg. This schedule mirrors the SURPASS and SURMOUNT clinical trial protocols. The 4-week hold at each dose level is not arbitrary: GLP-1 receptor agonists slow gastric emptying, and the GI adaptation window at each new dose level takes approximately 3-4 weeks to stabilize.

Escalating faster than every 4 weeks significantly increases nausea and vomiting rates. In the SURMOUNT-1 trial, participants who tolerated the 2.5 mg step for the full 4 weeks before escalating had substantially lower dropout rates due to GI adverse effects. If GI symptoms persist at a given dose level, remaining at that dose for an additional 4 weeks before the next increase is standard practice.

Vial math for titration: At 2.5 mg weekly, a 10 mg vial lasts 4 weeks. At 5 mg weekly, the same vial lasts 2 weeks. Plan vial supply around your current titration step. Once at 10-15 mg maintenance, one 10 mg vial covers roughly 1 week; most researchers source 10 mg vials in batches of 4.

Jastreboff et al. NEJM 2022 (SURMOUNT-1)

Step 3 of 3 · Storage

Reconstituted Vial Stability: What Actually Degrades Tirzepatide

Lyophilized (dry) Tirzepatide powder is stable at -20 degrees C for 12+ months and at 2-8 degrees C for several months before reconstitution. Once reconstituted with BAC water, the antimicrobial properties of the benzyl alcohol in BAC water extend the in-solution stability to approximately 28 days at 2-8 degrees C, versus 7-10 days if sterile water without preservative is used.

The primary degradation mechanisms for reconstituted Tirzepatide are thermal denaturation (heat above 25 degrees C) and repeated freeze-thaw cycles. Do not freeze reconstituted solution. UV light accelerates deamidation at asparagine residues, so amber or foil-wrapped vials are preferred for storage. A cloudy or particulate solution should be discarded.

Practical check: Before every draw, inspect the vial. Clear, colorless solution is correct. Any visible cloudiness, color change, or floating particles means the peptide has degraded or was contaminated and the vial should not be used.

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