Semaglutide (SEMA) 5 mg

At a Glance

Semaglutide is a synthetic GLP-1 receptor agonist that suppresses appetite, slows gastric emptying, and improves glucose regulation, achieving a mean 14.9% body-weight reduction over 68 weeks in the STEP 1 trial.[1] Research-grade semaglutide is used as a once-weekly subcutaneous injection following a slow titration schedule to minimise gastrointestinal side effects.

• Reconstitute: Add 2.0 mL bacteriostatic water → 2.5 mg/mL concentration.
• Starting dose: 0.25 mg once weekly (10 units / 0.10 mL) for the first 4 weeks.
• Easy measuring: At 2.5 mg/mL on a U-100 syringe, 1 unit = 0.01 mL ≈ 25 mcg.
• Storage: Lyophilised: freeze at −20 °C; reconstituted: refrigerate at 2–8 °C; use within 4 weeks; never freeze reconstituted solution.

Overview

• Goal: Progressive weight loss via GLP-1 receptor agonism — appetite suppression, reduced caloric intake, and improved glycaemic control.[1]
• Schedule: Once-weekly subcutaneous injection; dose escalated every 4 weeks.
• Dose range: 0.25 mg (initiation) → 2.4 mg (maintenance target).
• Reconstitution: 2.0 mL BAC water per 5 mg vial → 2.5 mg/mL.
• Storage: Lyophilised at −20 °C; reconstituted at 2–8 °C; use within 4 weeks.

What You’ll Need

Plan based on a 16-week titration to maintenance (Weeks 1–4: 0.25 mg; 5–8: 0.5 mg; 9–12: 1.0 mg; 13–16: 1.7 mg). Total dose = 14.0 mg.

• Semaglutide Vials (5 mg each): 14 mg cumulative → 3 vials.
• Insulin Syringes (U-100, 1 mL): 16 weekly injections → 16 syringes.
• Bacteriostatic Water (10 mL bottles): 2.0 mL per vial → 1 × 10 mL bottle per vial (3 bottles).
• Alcohol Swabs: 2 per injection → 32 swabs per 16-week course.

How to Reconstitute

1. Allow frozen lyophilised vial to reach room temperature (10–15 minutes).
2. Draw 2.0 mL bacteriostatic water with a sterile syringe.
3. Inject slowly down the inner vial wall; do not inject directly onto the powder cake.
4. Gently swirl or roll until fully dissolved — do not shake. Solution should be clear and colourless.
5. Label with reconstitution date; refrigerate at 2–8 °C, protected from light. Use within 4 weeks.

Dosing Schedule

Frequency: Inject once weekly on the same day each week. Slow titration minimises nausea, vomiting, and diarrhoea — the most common adverse effects.[1] At 2.5 mg/mL, the 5 mg vial provides approximately 2 doses at the 2.4 mg maintenance level or 20 doses at the 0.25 mg initiation level. Plan to purchase additional vials for the full titration course.

Protocol Details

• Weeks 1–4: 0.25 mg (10 units / 0.10 mL) once weekly — initiation and tolerability assessment.
• Weeks 5–8: 0.5 mg (20 units / 0.20 mL) once weekly.
• Weeks 9–12: 1.0 mg (40 units / 0.40 mL) once weekly.
• Weeks 13–16: 1.7 mg (68 units / 0.68 mL) once weekly.
• Weeks 17+: 2.4 mg (96 units / 0.96 mL) once weekly — maintenance.[2]

Storage

• Lyophilised: Store at −20 °C (−4 °F) or below; protect from moisture and light.
• Reconstituted: Refrigerate at 2–8 °C. Do not freeze. Use within 4 weeks.
• Appearance: Clear and colourless. Discard if cloudy, coloured, or particulate.

How Semaglutide Works

Semaglutide is a synthetic analogue of native GLP-1 with a C18 fatty-diacid side chain that promotes albumin binding, extending its half-life to approximately 7 days and enabling once-weekly dosing.[3]

Binding to GLP-1 receptors in the hypothalamus and brainstem reduces appetite and energy intake. In the pancreas, semaglutide augments glucose-dependent insulin secretion and suppresses glucagon. Delayed gastric emptying prolongs satiety. Collectively these effects produce the sustained caloric deficit that drives the clinical weight-loss outcomes observed in the STEP trials.[1]

Good to Know

• Inject on the same day each week to maintain consistent plasma levels (half-life ≈ 7 days).
• If a dose is missed by ≤5 days, administer as soon as possible; otherwise skip and resume the next scheduled day.
• Do not advance to the next dose tier if GI side effects are poorly tolerated — hold at the current dose for an additional 4 weeks.
• Monitor blood glucose when used alongside other glucose-lowering agents.
• Use a 1 mL (100-unit) syringe for doses above 0.50 mL (weeks 9+) for accurate measurement.
• Weight reduction: STEP 1 (n=1961): 14.9% mean weight loss vs. 2.4% placebo at 68 weeks with 2.4 mg/week semaglutide.[1]
• Cardiovascular protection: SELECT trial: 20% relative reduction in MACE in adults with obesity and established cardiovascular disease.[2]
• Glycaemic improvement: Significant HbA1c reductions across STEP and SUSTAIN trial series.
• GI side effects: Nausea (44%), diarrhoea (30%), vomiting (24%) — dose-dependent and typically transient; slow titration mitigates severity.
• Contraindications: History of medullary thyroid carcinoma, MEN2, or pancreatitis warrants particular caution.
• For background on Semaglutide's mechanism, evidence, and safety profile, see What Is Semaglutide?.

Tips for Best Results

• Pair with a reduced-calorie diet and regular physical activity to maximise and sustain weight-loss outcomes.
• Eat smaller, more frequent meals to minimise nausea — particularly during early titration phases.
• Stay well hydrated; GI side effects can increase dehydration risk.
• Track weekly body weight, waist circumference, and fasting glucose to assess response.

Injection Tips

• Clean the vial stopper and injection site with separate alcohol swabs; allow both to air-dry fully before proceeding.
• Using a 29–31 gauge insulin syringe (5/16″ to 1/2″ needle), draw the calculated dose precisely.
• Pinch a fold of skin and insert the needle at 45° into subcutaneous fat (90° is acceptable with a short needle into a well-pinched fold).
• Inject slowly over 2–3 seconds; do not aspirate. Withdraw the needle, apply gentle pressure, and do not rub the site.
• Rotate injection sites (abdomen, thighs, upper arms) and dispose of each syringe in a sharps container immediately after use.