How to reconstitute Semaglutide — visual step-by-step

What is reconstitution and why it matters for Semaglutide

Semaglutide is a GLP-1 receptor agonist — a 31-amino-acid peptide with a C-18 fatty acid chain that extends its half-life to approximately one week in human studies. Research vials ship as lyophilized powder, typically in 2 mg, 5 mg, or 10 mg quantities. The fatty diacid modification that gives semaglutide its long half-life also affects its solubility: the peptide may require slightly longer dissolution time than shorter, unmodified peptides. Accurate reconstitution is essential for reproducible research outcomes, especially for weekly dosing protocols where even small errors compound over multiple weeks.

Internal links: see the Semaglutide peptide profile at /peptides/semaglutide, the dosage guide for research-dose reference ranges, and /methodology.

Materials required

Gather: (1) Semaglutide research vial — commonly 2–10 mg lyophilized powder. (2) Bacteriostatic water for injection, 30 mL multi-dose vial. (3) Two 1 mL U-100 insulin syringes. (4) Two 70% isopropyl alcohol swabs. (5) Clean, flat workspace. (6) Sharps disposal container. (7) Permanent marker and label. Note: some researchers prefer a 3 mL syringe for larger volume draws (>1 mL) with 5 mg or 10 mg vials.

Step-by-step reconstitution protocol

Step 1 — Verify materials (see Diagram 1)

Confirm the semaglutide vial has white lyophilized powder. The BAC water should be clear and within its use-by date. Syringes should be sealed. Wash hands thoroughly.

Step 2 — Swab both septa

Swab the rubber septum of the BAC water vial with a 70% IPA swab in a single outward stroke. Allow 10–15 seconds to dry. Repeat with a fresh swab on the semaglutide vial. Do not touch the swabbed surfaces.

Step 3 — Draw bacteriostatic water (see Diagram 2)

Insert a fresh needle into the BAC water vial, invert, and draw the required volume. Common reconstitution volumes: For a 2 mg vial: 1.0 mL gives 2,000 mcg/mL; 2.0 mL gives 1,000 mcg/mL. For a 5 mg vial: 2.0 mL gives 2,500 mcg/mL; 5.0 mL gives 1,000 mcg/mL. Select a volume that yields a dose draw of at least 10–20 units on the syringe for accuracy. Confirm no air bubbles.

Step 4 — Introduce water against the glass wall (see Diagram 3)

Tilt the semaglutide vial at 45 degrees. Insert the needle through the septum and angle the tip toward the inner glass wall. Introduce the bacteriostatic water slowly down the wall. Due to semaglutide’s fatty acid modification, the powder may initially form a small layer at the liquid surface — this is normal and resolves with gentle swirling.

Step 5 — Gently swirl — allow up to 2 minutes

Gently roll the vial between your palms for up to 2 minutes. Semaglutide’s lipidated structure may dissolve more slowly than unmodified peptides. Do not shake. The finished solution should be clear and colorless. A very faint yellow tint is acceptable; cloudiness or particulates indicate a problem.

Step 6 — Label and refrigerate (see Diagram 4)

Label with peptide name, concentration, reconstitution date, and 28-day expiry. Refrigerate at 2–8°C. Do not freeze reconstituted semaglutide. For the commercially approved Ozempic pen, Novo Nordisk specifies 56 days of use after first use under refrigeration; for research vials in BAC water, the conservative 28-day guideline applies.

Dose math: translating research doses to U-100 syringe units

Example — 2 mg vial in 2.0 mL BAC water: 1,000 mcg/mL = 10 mcg per unit on a U-100 syringe. A 250 mcg research dose = 25 units. A 500 mcg dose = 50 units. A 1,000 mcg (1 mg) dose = 100 units (full 1 mL syringe). Example — 5 mg vial in 2.0 mL BAC water: 2,500 mcg/mL = 25 mcg per unit. A 500 mcg dose = 20 units. A 1,000 mcg dose = 40 units. Always verify your reconstitution volume before computing syringe draws.

Storage post-reconstitution

Reconstituted semaglutide in bacteriostatic water: refrigerate at 2–8°C for up to 28 days. Protect from light. Do not freeze. Inspect before each use — discard if any cloudiness or particulate matter develops. Semaglutide’s lipid modification makes it somewhat more stable in solution than shorter peptides, but the benzyl alcohol in BAC water is still the primary sterility preservative.

Common mistakes to avoid

Frequently asked questions