OK I feel really dumb asking this but I just received my compounded semaglutide vial and I'm completely lost on the reconstitution math. The vial says 5mg lyophilized semaglutide. My provider told me to start at 0.25mg per week.

I have bacteriostatic water and insulin syringes (1mL / 100 unit syringes). How much BAC water do I add, and then how many units do I draw up for each dose? I've been staring at this for an hour and I'm terrified of getting it wrong. Please help!! 😰

Don't feel dumb at all — this is legitimately confusing and the compounding pharmacies don't always explain it well. Let me walk you through it step by step.

Step 1: Choose your concentration. You get to decide how concentrated to make it based on how much BAC water you add. Common choices for a 5mg vial:

• Add 2mL BAC water → concentration = 5mg / 2mL = 2.5mg/mL
• Add 2.5mL BAC water → concentration = 5mg / 2.5mL = 2mg/mL
• Add 5mL BAC water → concentration = 5mg / 5mL = 1mg/mL

Step 2: Convert mL to insulin syringe units. On a standard U-100 insulin syringe, 1mL = 100 units. So:

• 0.1mL = 10 units
• 0.01mL = 1 unit

Step 3: Calculate your dose volume. If you add 2mL of BAC water (making 2.5mg/mL):

• 0.25mg dose = 0.25 / 2.5 = 0.1mL = 10 units
• 0.5mg dose = 0.5 / 2.5 = 0.2mL = 20 units
• 1.0mg dose = 1.0 / 2.5 = 0.4mL = 40 units

For a starting dose of 0.25mg, I'd recommend adding 2mL of BAC water, which gives you nice round numbers. You'd draw up to the 10-unit mark on your syringe.

That 5mg vial at 0.25mg/week gives you 20 weeks of doses. Make sure to store in the refrigerator after reconstitution.

Previously posted:

Add 2mL BAC water → concentration = 5mg / 2mL = 2.5mg/mL

OK this makes so much more sense now. So I literally just inject 2mL of bacteriostatic water into the vial, swirl gently, and then when it's dissolved I draw up 10 units on the insulin syringe for my 0.25mg dose?

And just to be triple sure — "10 units" on an insulin syringe is the same as 0.1mL right? The markings on my syringe go 10, 20, 30... up to 100.

Yes, exactly right on all counts! 10 units = 0.1mL on a U-100 syringe. You've got it.

Two important tips on the reconstitution process:

1. Inject the BAC water slowly down the side of the vial — don't spray it directly onto the powder. Peptides are delicate and direct force can denature them.
2. Swirl, don't shake. Gently roll the vial between your palms until the powder is fully dissolved. It should be clear and colorless. If it's cloudy or has particles floating around, don't use it.

The solution should dissolve within 1–3 minutes with gentle swirling. Some people leave it in the fridge for 10 minutes and come back — it'll often be fully dissolved by then.

One thing I'll add for anyone reading this later — if you're going to be titrating up through the standard doses (0.25 → 0.5 → 1.0 → 1.7 → 2.4mg), think ahead about your reconstitution volume.

With a 5mg vial reconstituted at 2.5mg/mL (2mL BAC water):

Notice that 2.4mg is almost a full 1mL syringe. That's a lot of volume for a subQ injection. If you're planning to go to higher doses, you might want to reconstitute with 1mL of BAC water instead (making 5mg/mL), which halves all those volumes. Tradeoff is the markings are tighter and you need to be more precise.