How to reconstitute Semaglutide

What needs mixing and what does not

Ozempic injection is a clear, colorless solution of 0.68, 1.34 or 2.68 mg/mL in prefilled pens, and it is also supplied as single-dose prefilled syringes.¹ Wegovy injection is supplied as a solution too, including Wegovy HD (7.2 mg in 0.75 mL) and a FlexTouch pen (9.6 mg in 3 mL).⁷ Rybelsus and the other semaglutide tablets are taken by mouth.² Only research vials, which hold a dry freeze-dried solid, need reconstitution.

Semaglutide injection sites on the approved pens

The semaglutide injection site options in the approved pens' instructions are the stomach area (abdomen), the thigh and the upper arm, with the injection given under the skin.⁴ The label lists the three areas without ranking them and says to rotate the site with each injection.⁴ Pens must never be shared between people, even if the needle is changed.¹

This section describes how the prescribed pens are used. It is not guidance for research vials. How subcutaneous injections are given covers prescribed injections and sharps disposal.

What a research vial holds

A research vial holds semaglutide as a white, freeze-dried (lyophilized) solid. The vials in our shop come in 2 mg, 5 mg, without diluent. No approved application covers research-labeled semaglutide, so FDA has reviewed no mixing or storage instructions for it.³

Check the label or certificate for the exact chemical form. FDA calls semaglutide salt forms, such as semaglutide sodium and semaglutide acetate, different active ingredients from the one in approved drugs.⁹ Check the lab results page for testing documentation.

Lab steps

1. Read the vial label: compound, strength in mg and lot number. Record them with the date.
2. Pick a target concentration and work out the diluent volume, using the math below or the reconstitution calculator.
3. Wipe the rubber stopper with an alcohol swab and use a sterile needle and syringe. The Bacteriostatic Water for Injection label calls for aseptic technique at every entry into and withdrawal from a container.¹⁵
4. Draw the measured diluent, aim the stream at the inside wall of the vial rather than onto the solid, and swirl gently until it dissolves. The label of one approved freeze-dried product, ZOMACTON (somatropin), gives this method and says not to shake, because shaking or vigorous mixing makes the solution cloudy.¹⁶
5. Check the solution: the diluent's label says to inspect dissolved drugs for clarity and for unexpected particles or discoloration.¹⁵
6. Label the vial with its concentration in mg/mL and the date it was first entered.
7. Store it as described in the storage section below.

The general method, with more detail on technique, is in How to reconstitute a peptide vial.

Concentration math

Concentration (mg/mL) = semaglutide in the vial (mg) ÷ diluent added (mL).

Amount in a volume (mg) = concentration (mg/mL) × volume (mL).

More diluent makes a weaker solution; the total amount in the vial stays the same. The labeled mg may not all be peptide: Bachem notes that peptide powders also hold counter-ions and water, so peptide content may be 70 to 90% even at high purity, and says this must be taken into account when preparing a solution of defined concentration.¹³ The peptide calculator and the units converter run the same arithmetic for other numbers.

Where vial measuring errors come from

FDA has received reports of people taking five to 20 times the intended amount of semaglutide from compounded vials, and some needed hospital care.¹⁰¹¹ It traced the errors to self-measured doses and to confusion between milliliters, milligrams and 'units', and it urged that patients get the right syringe size and instruction on measuring.¹⁰ In the lab, writing the concentration in mg/mL on the vial and recording every volume in mL keeps the units consistent.

Storage

No FDA-reviewed storage instructions exist for research-labeled semaglutide.³ No stability data specific to it were found in the sources used for this page, so these are reference points, not tested limits:

• Freeze-dried peptides in general: Bachem advises a tightly closed container below -15 °C for longer storage, or a refrigerator at 4 °C for short-term use.¹²
• Dissolved peptides: Bachem advises against storing peptides in solution, even sterile solution, because they slowly break down, and the diluent's label says to use dissolved drugs promptly.¹²¹⁵
• Opened multiple-dose vials: CDC guidance is to date the vial when it is first punctured and discard it within 28 days unless the manufacturer states another date.¹⁴
• Ozempic pens: refrigerated at 2°C to 8°C (36°F to 46°F) before first use, then up to 56 days at 15°C to 30°C (59°F to 86°F). They are never frozen and are kept from excessive heat and sunlight.⁵
• Wegovy pens: refrigerated at 2°C to 8°C, or kept at 8°C to 30°C (46°F to 86°F) in the original carton for up to 28 days, and never frozen.⁶
• Compounded multiple-dose GLP-1 vials: FDA says to discard them within 28 days after first use, even if some remains, and not to use any that arrive warm or poorly refrigerated.⁸

General guidance is in How to store peptides.

Supplies

Bacteriostatic water is the diluent listed for semaglutide vials. Hospira's label for Bacteriostatic Water for Injection describes sterile water with 0.9% or 1.1% benzyl alcohol as a preservative in a multiple-dose vial, and warns that it is not for use in newborns.¹⁵ A 3 mL Luer-Lok syringe with an 18G 1-inch needle draws and transfers diluent, insulin syringes measure small volumes, and alcohol swabs clean the stopper. Peptide supplies explained describes each item.

Related pages

Back to What is Semaglutide?. See also Semaglutide dosage, Semaglutide side effects and Semaglutide benefits and uses.