Semaglutide (5 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 5 mg vial.
⚡ Quickstart Highlights
Dosing & Reconstitution Guide
Route: Subcutaneous | Frequency: Once weekly | Half-life: ~7 days
Standard Approach (3 mL = 1.67 mg/mL)
Reconstituting with 3 mL bacteriostatic water produces a concentration of 1.67 mg/mL. Volume per dose changes with concentration; mg dose itself does not change between vial sizes.
| Phase / Protocol | Dose | U-100 Units | Volume | Doses per vial |
|---|---|---|---|---|
| Weeks 1–4 (titration) | 250 mcg | 15 units | 0.15 mL | 20 doses |
| Weeks 5–8 | 500 mcg | 30 units | 0.30 mL | 10 doses |
| Weeks 9–12 | 1 mg | 60 units | 0.60 mL | 5 doses |
| Weeks 13–16 | 1.7 mg | 102 units | 1.02 mL | 2 doses |
| Weeks 17+ (maintenance) | 2.4 mg | 144 units | 1.44 mL | 2 doses |
Reconstitution Steps
- Wipe the vial stopper and BAC water vial with alcohol; let dry.
- Draw 3 mL of bacteriostatic water into a sterile syringe.
- Inject slowly down the inside glass wall of the peptide vial. Do not aim at the powder.
- Gently swirl until fully dissolved. Do not shake.
- Label with reconstitution date. Refrigerate at 2–8°C; use within 28 days.
Supplies Needed
Estimates for an 8-week and 12-week cycle at 2.4 mg per dose, once weekly (1 dose/week).
| Item | 8-Week Cycle | 12-Week Cycle |
|---|---|---|
| Semaglutide (5 mg) vials | 4 vials | 6 vials |
| Insulin syringes (U-100) | 8 | 12 |
| Bacteriostatic water (10 mL) | 2 × 10 mL | 2 × 10 mL |
| Alcohol swabs | 1 × 100-pack | 2 × 100-pack |
Protocol Overview
The STEP-1 protocol — the original landmark obesity trial — uses a 4-step titration over 16 weeks before reaching the 2.4 mg maintenance dose. Semaglutide's once-weekly dosing and 7-day half-life make it forgiving on timing but slow to clear if side effects become a problem.
Most research protocols run 6–18 months. In STEP-1 the weight-loss curve was still trending downward at week 68 (final measurement), suggesting longer protocols may produce additional benefit.
Cycle length: Continuous use for 6–18 months in most protocols. Some users transition to a "maintenance" 1.0–1.7 mg weekly dose after reaching target, rather than the full 2.4 mg, to preserve results with reduced side-effect load.
What to expect by week: Weeks 1–4 — mild appetite suppression begins. Weeks 5–16 — titration phase, weight-loss curve gradually steepens. Weeks 17–32 — primary weight-loss phase. Weeks 32+ — gradual continued loss, plateau approach.
Dosing Protocol
Standard STEP-1 obesity protocol — 4-week titration intervals:
- Weeks 1–4: 0.25 mg once weekly. Tolerability assessment.
- Weeks 5–8: 0.50 mg once weekly.
- Weeks 9–12: 1.00 mg once weekly.
- Weeks 13–16: 1.70 mg once weekly. Optional intermediate step.
- Weeks 17+ (maintenance): 2.40 mg once weekly. STEP-1 maintenance dose.
SUSTAIN T2DM protocol: Same titration steps but maintenance often at 1.0 mg weekly, which produced the cardiovascular benefit in SUSTAIN-6.
Slower titration variant: Some research protocols hold each step for 6–8 weeks instead of 4 if GI tolerability is poor. This extends the time to maintenance but reduces dropout from side effects.
Day-of-week timing: Same day each week. Half-life ~7 days — the longest of the GLP-1 class. Doses can shift ±2 days without affecting steady state.
Missed dose: ≤5 days late, take when remembered. >5 days, skip and resume next scheduled day.
Maintenance reduction: Once at target weight, many users drop to 1.7 mg or 1.0 mg weekly indefinitely to maintain results with fewer side effects.
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.