Zepbound vials: single-dose and multi-dose

Zepbound comes in two kinds of vial: a single-dose vial that holds one 0.5 mL dose and is thrown away after use, and a multi-dose vial that holds 2.4 mL, enough for four weekly doses of 0.6 mL. Both are ready-made liquids in the same six strengths as the pens, and for both the label says to draw your dose with a new syringe and needle, for example a 1 mL syringe (Zepbound label, sections 2.4, 3 and 11).

The labels measure vial doses in mL, not units. If your instructions are written in syringe units, the tirzepatide units calculator converts the dose your prescriber gave you, and the arithmetic section below shows how the labeled volumes read on a U-100 syringe.

The vial presentations

The Zepbound label lists six strengths for each vial type. Single-dose vials come in cartons of 1 or 4; the multi-dose vial comes 1 per carton (Zepbound label, sections 3 and 16.1):

A few details in the label that are easy to miss:

• The multi-dose vial’s mg/mL is rounded. Each dose is defined as the dose per 0.6 mL, so measure by the 0.6 mL line, not by redoing the math from the printed strength.
• The multi-dose vial contains preservatives. Each dose includes benzyl alcohol (5.4 mg) and phenol (1.08 mg); the single-dose vial lists no preservative (Zepbound label, section 11).
• Mounjaro’s vials match, with one difference. Mounjaro lists the same strengths and volumes, but its single-dose vials come 1 per carton, with no 4-pack (Mounjaro label, section 16.1).
• Nothing is added. Every labeled tirzepatide product is a solution, and no label mentions adding water or any other liquid. A tirzepatide vial that arrives as a powder is not Zepbound: it is compounded or unapproved, and compounded drugs are not FDA-approved (FDA Q&A).

How vials differ from pens

The label asks prescribers to tell you which presentation you’ll receive and to make sure you’re trained on that one, and to retrain you if it changes (Zepbound label, section 2.4). Switching from a pen to a vial, or from a single-dose to a multi-dose vial, is a new technique: read the Instructions for Use that came with it.

Drawing a dose from a vial

The single-dose and multi-dose vial Instructions for Use give the same steps; only the volume changes. Here they are for the single-dose vial, with the multi-dose figure in brackets:

1. Get your supplies

   One syringe and one needle (for example, a 1 mL syringe and needle as your healthcare provider recommends), an alcohol swab, gauze and a sharps container. “Always use a new syringe and needle for each injection.”

2. Prepare the vial

   Pull off the plastic protective cap (on a multi-dose vial, only the first time), but “do not remove the rubber stopper.” Wipe the stopper with an alcohol swab. Check the liquid is clear and colorless to slightly yellow, with no particles.

3. Draw in air

   Attach the needle if it isn’t already, remove the shield, and pull the plunger to the 0.5 mL [0.6 mL] line to draw in air. Push the needle through the stopper and push the plunger all the way in. This “makes it easier to pull the solution from the vial.”

4. Draw the dose

   Turn the vial and syringe upside down, keep the needle tip in the liquid, and pull the plunger past the 0.5 mL [0.6 mL] line. Tap the syringe gently so any air bubbles rise, then push the plunger up until its tip reaches the 0.5 mL [0.6 mL] line. Pull the syringe out of the stopper.

5. Inject

   Inject under the skin of your stomach or thigh, or have someone else use the back of your upper arm, as your healthcare provider showed you. Keep the needle in “for at least 5 seconds” to make sure you’ve injected the whole dose. “Do not recap the needle.”

Source: the single-dose and multi-dose vial Instructions for Use in the Zepbound label. The same Instructions say not to mix Zepbound with any other medicine, and not to inject it in the same site used for other medicines. Rotate sites each week “to reduce your risk of getting lipodystrophy (pits in skin or thickened skin) and localized cutaneous amyloidosis (skin with lumps)”; see subcutaneous injection sites.

The labeled volumes in syringe units

The labels say “a 1 mL syringe capable of measuring a 0.5 mL or 0.6 mL dose” and give doses in mL. If your syringe is marked only in units, here is how those volumes read at two labeled strengths. First, the 10 mg single-dose vial (10 mg/0.5 mL, so 20 mg/mL):

The amount in each syringe reading at 20 mg/mL.

Reading	Volume	Amount
30 units	0.3 mL	6 mg
50 units	0.5 mL	10 mg

U-100 syringe: 100 units = 1 mL. At a different strength the same reading holds a different amount.

A full 30-unit syringe holds less than the whole single-dose vial, which is one reason the label names a 1 mL syringe. Next, the 60 mg/2.4 mL multi-dose vial (25 mg/mL), comparing the two lines:

The amount in each syringe reading at 25 mg/mL.

Reading	Volume	Amount
50 units	0.5 mL	12.5 mg
60 units	0.6 mL	15 mg

U-100 syringe: 100 units = 1 mL. At a different strength the same reading holds a different amount.

Stopping at the single-dose line on a multi-dose vial gives you less than the labeled 15 mg dose. If you move from single-dose to multi-dose vials, or the other way, check which line you draw to. For a dose in units on any other strength, see how many units is 2.5 mg of tirzepatide or use the calculator.

Storage and when to throw a vial away

All Zepbound vials go in the refrigerator at 2°C to 8°C (36°F to 46°F), in the original carton to protect from light. Don’t freeze them, and don’t use one that has been frozen (Zepbound label, section 16.2). The two vial types then follow different rules:

Sources: the Zepbound label, section 16.2, and the vial Instructions for Use (Zepbound label). The FDA also recommends not using any injectable GLP-1 drug “that arrives warm or with insufficient refrigeration” (FDA). For trips, see storing GLP-1 pens and traveling.

Used needles and syringes go in an FDA-cleared sharps container right away, not loose in household trash (Zepbound label, Instructions for Use). See sharps disposal for what to use if you don’t have one.

Questions people ask