What Semaglutide is
Semaglutide is a GLP-1 receptor agonist, FDA approved as Ozempic for type 2 diabetes (maximum 2.0 mg weekly) and Wegovy for weight management (maximum 2.4 mg weekly). With a half-life of about one week it is dosed once weekly, and a missed dose barely dents the steady-state level.
The doses in the table are the Wegovy escalation steps, the schedule most compounded semaglutide protocols mirror.
Reconstitution math
Concentration is everything: the same 5 mg vial gives a different draw for every amount of bacteriostatic water you add. The table uses the common 2 mL setup for each vial size, which puts every unit on a U-100 insulin syringe at 25 mcg for the default vial. Dashes mark draws too small to measure or larger than the syringe.
| Vial | BAC water | Concentration | 0.25 mg | 0.5 mg | 1 mg | 1.7 mg | 2.4 mg |
|---|---|---|---|---|---|---|---|
| 2 mg | 2 mL | 1 mg/mL | 25 u | 50 u | 100 u | - | - |
| 5 mg | 2 mL | 2.5 mg/mL | 10 u | 20 u | 40 u | 68 u | 96 u |
| 10 mg | 2 mL | 5 mg/mL | 5 u | 10 u | 20 u | 34 u | 48 u |
| 15 mg | 2 mL | 7.5 mg/mL | 3.3 u | 6.7 u | 13.3 u | 22.7 u | 32 u |
Dosing and protocol
Wegovy titration: 0.25 to 2.4 mg weekly, four weeks per step.
The 0.25 and 0.5 mg starting steps are small: on a 5 mg vial with 2 mL of water they come to 10 and 20 units on an insulin syringe. If your draws land under 5 units, add more water rather than eyeballing a 2-unit draw; the reverse calculator solves for the volume that puts your dose on a clean mark.
Pharmacokinetics
Semaglutide has published human pharmacokinetics: peak roughly 1 to 3 days after a subcutaneous dose. The curves below are normalized one-compartment models built from the cited half-life, the same math the Planner uses. They show shape and timing, not absolute blood levels.
Storage and handling
Lyophilized vials keep best cold, dark, and dry; refrigeration is the community default and freezing lyophilized powder is common for long holds. After reconstitution, refrigerate at 2 to 8 C, do not freeze the solution, and date the vial. Bacteriostatic water's preservative keeps multi-dose use practical for about 28 days by USP convention, though our 120-day stability study found the preservative itself outlasts that window.
Novo Nordisk labels the pens for refrigeration with defined in-use windows (up to 56 days for Ozempic). The same refrigerate-after-mixing rule applies to reconstituted vials.
Got a certificate of analysis with your vial? Run it through our COA Reader: it reads the report in plain English, checks purity and mass against the label claim, and links the testing lab’s own verification page. Our guide to reading a COA explains what the numbers do and do not tell you.
Sources
- Wegovy prescribing information (Novo Nordisk, 2023)
- Hall et al., Clinical pharmacokinetics of semaglutide: a systematic review, Drug Des Devel Ther 2024
- Wilding et al., Once-weekly semaglutide in overweight or obesity (STEP 1), NEJM 2021