Semaglutide
GLP-1 Receptor AgonistAlso known as: Ozempic · Wegovy · Rybelsus
A once-weekly GLP-1 analog with FDA approval for type 2 diabetes & obesity. The most widely verified peptide in the Certipep ledger.
Typical Dose
0.5–2.4 mg once weekly (subcutaneous); 7–14 mg daily (oral)
Route
Subcutaneous injection (once weekly); oral tablet
Cycle
Continuous; dose escalation over 16–20 weeks to maintenance
Half-life
~7 days
Storage
Reconstituted: 2–8°C, use within 28 days. Pen devices: 2–8°C (unused), room temp up to 56 days (in-use).
Overview
Semaglutide is a synthetic analog of glucagon-like peptide-1 (GLP-1) with 94% sequence homology to the native hormone. Fatty acid modification & minor substitutions extend its half-life from ~2 minutes (native GLP-1) to approximately 7 days, enabling once-weekly subcutaneous administration or daily oral use.
It acts on GLP-1 receptors in the pancreas (glucose-dependent insulin secretion, glucagon suppression), hypothalamus (appetite reduction, delayed gastric emptying), & cardiovascular system (demonstrated MACE reduction in SUSTAIN-6 & SELECT trials). The result is significant weight loss (15–17% of body weight in STEP trials) & improved glycemic control.
Compounded semaglutide is widely circulated as a research peptide. Certipep testing has confirmed identity via ESI-TOF-MS across multiple manufacturers, with purity variance being the primary quality differentiator.
Quick Start Guide
Reconstitute compounded lyophilized semaglutide with the included diluent or bacteriostatic water.
Start at 0.25 mg subcutaneously once weekly for 4 weeks (dose escalation reduces GI side effects).
Escalate by 0.25–0.5 mg every 4 weeks to a target of 1–2.4 mg/week based on tolerance.
Inject into abdomen, thigh, or upper arm. Rotate sites weekly.
Refrigerate after reconstitution. Allow to reach room temperature before injecting.
Research Indications
Weight loss / obesity
Most EffectiveSTEP trials: 15–17% mean body weight reduction vs 2.4% placebo at 68 weeks. STEP 1 showed ~15% loss at 2.4 mg/week.
Type 2 diabetes (glycemic control)
Most EffectiveFDA approved; reduces HbA1c by 1.5–2%. SUSTAIN trial program across 7 trials.
Cardiovascular risk reduction
EffectiveSELECT trial (2023): 20% reduction in MACE in overweight/obese adults without diabetes.
Non-alcoholic fatty liver disease (NASH)
ModerateNASH resolution in 59% vs 17% placebo in Phase II. Phase III trials ongoing.
Research Protocols
Weight loss (standard escalation)
16–20 week escalation; then maintain at highest tolerated doseDose
0.25 mg → 0.5 mg → 1 mg → 1.7 mg → 2.4 mg
Frequency
Once weekly SubQ
Route
SubQ abdomen/thigh
Increase dose every 4 weeks. Stop escalation if tolerability is poor; stay at current dose for another 4 weeks before trying again.
Glycemic control (T2D)
ContinuousDose
0.5–1 mg once weekly
Frequency
Once weekly SubQ
Route
SubQ abdomen/thigh
Peptide Interactions
Do not combine; both are injectable GLP-1 agonists. Switching from one to the other requires a washout given the 7-day half-life.
Same class; do not combine.
Side Effects & Safety
Common
- Nausea (most common, especially during escalation; typically subsides within 4–8 weeks)
- Vomiting
- Diarrhea or constipation
- Decreased appetite
- Injection site redness or bruising
Uncommon
- Pancreatitis (rare; discontinue if suspected)
- Gallbladder disease / cholelithiasis
- Tachycardia (small increase in resting heart rate)
- Hypoglycemia (rare without concomitant insulin/sulfonylurea)
When to Stop
- Personal or family history of medullary thyroid carcinoma or MEN2 (black box warning)
- Signs of pancreatitis: severe persistent abdominal pain radiating to back
- Diabetic retinopathy complications
- Signs of allergic reaction
How to Reconstitute
Wipe the vial stopper with an alcohol swab & allow to dry.
Draw the prescribed volume of bacteriostatic water or supplied diluent into a syringe.
Inject slowly down the inner wall of the vial. Gently swirl; do not shake.
Allow to sit for 2–3 minutes if powder does not dissolve immediately; semaglutide can take slightly longer than smaller peptides.
Solution should be clear & colorless. Label & refrigerate.
Dosing math: Concentration varies by compounding pharmacy. Common: 5 mg/mL (0.25 mg = 0.05 mL) or 2.5 mg/mL (0.25 mg = 0.1 mL). Confirm concentration on your vial label before drawing.
Quality Indicators
Good — use as normal
- Crystal clear, colorless solution
- No particulate after reconstitution
Acceptable
- Very faint yellowish tint consistent across the batch
Discard immediately
- Persistent cloudiness
- Visible particulate
- Brown or strong yellow discoloration
- Any doubt about storage integrity
What to Expect
Weeks 1–4 (0.25 mg)
Most users experience nausea in week 1–2. Appetite suppression begins. Weight loss of 0.5–1 kg is typical at this low dose.
Weeks 5–8 (0.5 mg)
GI side effects usually improving. Appetite suppression is more pronounced. 2–4 kg total loss expected.
Weeks 9–16 (1–1.7 mg)
The majority of weight loss occurs in this range. Energy & satiety improvements are stable. Many users notice significant improvement in food noise (intrusive food thoughts).
Weeks 17+ (maintenance)
At 2.4 mg, studies show continued slow loss through 68 weeks. Weight plateaus at a new set point & regain occurs if discontinued.
Community Insights
Self-reported. Reflects user experience, not clinical outcomes.
Research References
New England Journal of Medicine · 2021
Phase III RCT; 2.4 mg semaglutide produced 14.9% mean weight loss vs 2.4% placebo at 68 weeks.
doi:10.1056/NEJMoa2032183 →New England Journal of Medicine · 2023
20% reduction in MACE in 17,604 overweight/obese adults without diabetes over 3.3 years.
doi:10.1056/NEJMoa2307563 →Verify what you have
Information on this page applies to pharmaceutical-grade peptides. Purity & identity of research-grade products vary. Certipep provides independent ESI-TOF-MS & HPLC analysis with a signed analytical report.
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