Compounded Tirzepatide: How to Reconstitute and Calculate Dose

The quick answer

Compounded tirzepatide typically arrives as a lyophilized powder or pre-mixed vial. For powder vials: inject bacteriostatic water slowly, swirl gently, refrigerate. For pre-mixed vials: no reconstitution needed — check the label concentration and calculate your draw. Use the tirzepatide reconstitution calculator to get your exact syringe units.

Compounded vs. brand-name tirzepatide

Brand-name tirzepatide (Mounjaro® for type 2 diabetes, Zepbound® for weight management) comes in a pre-filled auto-injector pen. No reconstitution required — the dose is pre-set. If you're on the pen, skip this page.

Compounded tirzepatide is manufactured by licensed 503A/503B compounding pharmacies for individual patient prescriptions. It typically comes in one of two forms:

• Lyophilized powder vial — freeze-dried powder that requires reconstitution with bacteriostatic water before injection. You choose the bac water volume and calculate the draw.
• Pre-mixed vial — already dissolved at a specific concentration labeled on the vial (commonly 2.5 mg/mL, 5 mg/mL, 10 mg/mL, 17 mg/mL, or 20 mg/mL). No reconstitution needed — just calculate units from the labeled concentration.

Confirm which type you have by reading the vial label before doing any math. Your pharmacy should have told you; if they didn't, call and ask.

Reconstituting a powder vial

If your tirzepatide arrived as lyophilized powder, here is the process:

1. Allow to warm. Let the vial and bacteriostatic water sit at room temperature for 15–30 minutes. Cold-to-cold mixing reduces foaming.
2. Clean both stoppers. Wipe each rubber stopper with a fresh alcohol swab and allow to air-dry for 30 seconds before inserting a needle.
3. Draw the bac water. Pull the prescribed bac water volume into a syringe. Your pharmacy or prescriber should specify how much to add; if not, confirm before proceeding.
4. Inject slowly against the glass wall. Insert the needle into the tirzepatide vial and angle so bac water runs down the inside of the glass — not directly onto the powder. Inject slowly.
5. Swirl, do not shake. Slowly rotate the vial for 30–60 seconds. Tirzepatide can take several minutes to fully dissolve. The solution should be clear and colorless or very slightly yellow. Do not inject if cloudy or particulate matter is visible.
6. Label and refrigerate. Mark the vial with the reconstitution date and bac water volume added. Refrigerate immediately. Use within 28 days.

Calculating units to draw

Once reconstituted (or if you have a pre-mixed vial), the calculation is the same as any other peptide:

1. Concentration (mg/mL) — for a powder vial, this is your vial strength ÷ bac water added. For a pre-mixed vial, read it off the label.
2. Volume (mL) = Prescribed dose (mg) ÷ Concentration (mg/mL)
3. Units (U100 syringe) = Volume (mL) × 100

Example — 5 mg/mL pre-mixed vial, 2.5 mg prescribed dose

Volume: 2.5 mg ÷ 5 mg/mL = 0.50 mL. Units: 0.50 × 100 = 50 units.

Example — 10 mg lyophilized vial + 2 mL bac water, 5 mg dose

Concentration: 10 mg ÷ 2 mL = 5 mg/mL. Volume: 5 mg ÷ 5 mg/mL = 1.0 mL. Units: 1.0 × 100 = 100 units (a full 1 mL syringe).

Tirzepatide dose escalation and tracking

Tirzepatide protocols involve dose escalation — starting low and increasing over weeks to reduce GI side effects. A typical compounded protocol might start at 2.5 mg/week and increase by 2.5 mg every 4 weeks, targeting 10–15 mg/week.

What makes tracking important here: each escalation step changes the number of units you draw. If you're on a 5 mg/mL vial and escalate from 5 mg to 7.5 mg, your draw goes from 100 units to 150 units — a 50% change. Getting this wrong means significantly over- or under-dosing.

My Pep Calc's dose log lets you update the target dose per compound so the calculator always reflects your current escalation step, not last month's.

Half-life: why weekly dosing works

Tirzepatide has a half-life of approximately 5 days (120 hours) — one of the longest of any injectable in this class. This is why once-weekly dosing maintains effective steady-state concentrations. After four weeks of weekly dosing, blood levels plateau at roughly 2–3× the peak of a single dose.

Contrast this with BPC-157's 4-hour half-life or semaglutide's approximately 7-day half-life. Tirzepatide's 5-day half-life means if you miss a dose by 2 days, concentrations drop but don't crash the way a short-half-life compound would.

Use the half-life chart to visualize tirzepatide accumulation and clearance across your dosing schedule.

Storage

Unreconstituted lyophilized powder: Refrigerate at 2–8 °C. Protect from light. Do not freeze.

Reconstituted solution: Refrigerate at 2–8 °C immediately after reconstitution. Use within 28 days. Do not freeze. Discard if cloudy or discolored.

Pre-mixed vials: Follow label instructions. Most compounded pre-mixed vials are refrigerated from the pharmacy and remain stable 28–56 days refrigerated. Check the beyond-use date on the label.

Regulatory status

Brand-name tirzepatide (Mounjaro, Zepbound) is FDA-approved. Compounded tirzepatide from 503A/503B pharmacies was available under shortage provisions through early 2026. Regulatory status is actively evolving — confirm current legal availability with your prescribing provider before obtaining compounded versions.

My Pep Calc is a tracking tool. We don't sell or source tirzepatide and don't have financial relationships with any pharmacy or telehealth provider.