Semaglutide GLP-1 SM (20 mg Vial) Dosage Protocol
Semaglutide is a long-acting GLP-1 receptor agonist studied in landmark Phase 3 trials (STEP, SUSTAIN). Standard maintenance for weight protocols is 2.4 mg weekly. This page covers the 20 mg vial.
⚡ Quickstart Highlights
Dosing & Reconstitution Guide
The same published weekly escalation schedule converted for a 20 mg vial
Standard Weekly Escalation Schedule (3 mL = 6.67 mg/mL)
| Study Phase | Weekly Amount | U-100 Units | Volume |
|---|---|---|---|
| Weeks 1 to 4 | 0.25 mg | 3.75 units | 0.0375 mL |
| Weeks 5 to 8 | 0.5 mg | 7.5 units | 0.075 mL |
| Weeks 9 to 12 | 1 mg | 15 units | 0.15 mL |
| Weeks 13 to 16 | 1.7 mg | 25.5 units | 0.255 mL |
| Weeks 17+ | 2.4 mg | 36 units | 0.36 mL |
Frequency: Once weekly by subcutaneous administration. The current injectable semaglutide schedule starts at 0.25 mg for four weeks, then increases at four-week intervals to 0.5 mg, 1 mg, and 1.7 mg. The usual recommended adult weight-reduction maintenance amount is 2.4 mg once weekly.
Reconstitution Steps
- Clean the vial stopper and gather the sterile supplies required by the research procedure.
- Add 3 mL of the documented sterile diluent slowly down the vial wall.
- Gently swirl or roll until dissolved. Do not shake.
- Label the vial 6.67 mg/mL with the preparation date and follow the exact formulation storage and discard instructions.
The weekly amounts remain identical across the Semaglutide family. The 20 mg vial changes only concentration, U-100 units, volume, and supply calculations.
Supplies Needed
Clear 12-week and 24-week planning for a 20 mg vial at 6.67 mg/mL.
| Item | 12-week schedule | 24-week schedule |
|---|---|---|
| Semaglutide vials (20 mg each) | 1 vial needed. Total scheduled amount: 7 mg. | 2 vials needed. Total scheduled amount: 33 mg. |
| U-100 insulin syringes (1 mL capacity) | 12 new syringes needed. | 24 new syringes needed. |
| Documented sterile diluent (10 mL bottles) | 1 bottle needed. Total diluent volume: 3 mL. | 1 bottle needed. Total diluent volume: 6 mL. |
| Alcohol swabs | 24 swabs minimum. 1 box of 100 covers this minimum. | 48 swabs minimum. 1 box of 100 covers this minimum. |
Sharps disposal: One appropriately sized container for used syringes.
Stability planning: Vial, syringe, swab, and diluent totals are minimum arithmetic quantities for the standard schedule shown. Follow the exact product documentation for sterility, storage, handling loss, and discard timing.
Storage Instructions
| State | Temperature | Duration |
|---|---|---|
| Lyophilized | −20°C (−4°F) | Up to 24 months, dry & dark |
| Reconstituted | 2–8°C (35–46°F) | Up to 28 days, protect from light |
Important Notes
How This Works
Semaglutide is a 31-amino-acid synthetic analog of native GLP-1. Two modifications give it a half-life of ~7 days vs minutes for native GLP-1: substitution of alanine at position 8 (preventing DPP-4 degradation) and a fatty-acid linker that binds albumin.
It activates GLP-1 receptors in pancreatic beta cells (enhancing insulin secretion), the hypothalamus (suppressing appetite), and the gut (slowing gastric emptying). Insulin response is glucose-dependent, so hypoglycemia risk is low as monotherapy.
Potential Benefits & Side Effects
Potential Benefits
- STEP-1: 14.9% body-weight reduction at 2.4 mg weekly over 68 weeks vs 2.4% placebo.
- SUSTAIN-6: 26% reduction in major cardiovascular events in T2DM with established CVD.
- HbA1c reductions of 1.5–1.8% across SUSTAIN program.
- Improvements in blood pressure and lipid profile.
Side Effect Profile
- Nausea (most common — usually mild during titration).
- Vomiting and diarrhea, particularly during dose escalation.
- Constipation in some users.
- Decreased appetite (intended).
- Rare: pancreatitis, gallbladder events.
Lifestyle Factors
- Hydrate aggressively — GLP-1 agonists blunt thirst.
- Protein 1.0–1.6 g/kg/day to preserve lean mass.
- Resistance training 2–3×/week.
- Limit high-fat meals during the first 24 hours after dosing.
- Smaller, more frequent meals; avoid eating to fullness.
Injection Technique
- Inject subcutaneously into abdomen, outer thigh, or upper arm — rotate weekly.
- Avoid 2-inch radius around navel.
- 90° angle with short (4–8 mm) insulin needles.
- Bring vial to room temperature 15 min before injecting.
- Hold 5–10 seconds after full plunger depression.