Tirzépatide
Double agoniste des récepteurs GIP / GLP-1
Tirzepatide is a dual GIP and GLP-1 receptor agonist, two incretin hormones involved in regulating blood glucose and appetite. It acts on satiety, glucose-dependent insulin response, and energy metabolism.
Chemical identity
- Sequence
- 39-mer modifié (2× Aib, Lys20 acylée C20 diacide ; amide C-terminal)
- Molecular formula
- C225H348N48O68
- Molecular weight
- 4813.53 g/mol
- CAS no.
- 2023788-19-2
Purity (HPLC) measures the absence of related impurities; it is distinct from net peptide content, since salts and counter-ions (acetate, TFA) count toward the vial mass. Account for this when computing the real concentration at reconstitution.
Potential benefits
Reduced appetite
Acts on central satiety signals to naturally decrease hunger.
Stabilized blood glucose
Improves glucose-dependent insulin secretion and insulin sensitivity.
Prolonged satiety
Slows gastric emptying, extending the feeling of fullness.
Body composition
Promotes fat mass reduction as part of a caloric deficit.
Mechanism of action
- GLP-1: activates POMC/CART neurons (satiety), inhibits NPY/AgRP (hunger), slows gastric emptying.
- GIP: enhances glucose-dependent insulin response and modulates lipid metabolism.
- Dual GIP + GLP-1 activation creates a synergy on glycemic control and appetite that is superior to a GLP-1 agonist alone.
- Long half-life (~5 days) → gradual accumulation; steady state reached after about 4 weeks at a stable dose.
- Glucose-dependent insulin secretion: the action is modulated according to blood glucose levels, limiting the risk of hypoglycemia in monotherapy.
Historical milestones
Research milestones, clinical trials and regulatory steps.
- 2019
Phase 3 trials begin
The SURPASS (diabetes) and SURMOUNT (obesity) programs start, evaluating tirzepatide over 72 weeks.
- May 2022
FDA approval (diabetes)
The FDA approves tirzepatide as Mounjaro for type 2 diabetes on 13 May 2022.
- 2022
SURMOUNT-1 results
The SURMOUNT-1 obesity trial shows up to about 21% body-weight loss on the 15 mg dose over 72 weeks.
- Nov 2023
FDA approval (obesity)
The FDA approves the same molecule as Zepbound for weight management on 8 November 2023.
- 2024
Indication expansion
New indications are approved, including obesity-related obstructive sleep apnea.
Evolution over time
Initial adaptation (2.5 mg): reduced appetite, possible early digestive effects.
Dose increase: more pronounced satiety, more stable energy, onset of fat mass loss.
Progression: more steady weight loss, better management of portions and cravings.
Dosages & protocol
Reference dosages
12 wk
Fixed day each week (evening for tolerability)
~5 days (~120 h) — compatible with a single weekly injection
Titration protocol
Stay on one step and let natural accumulation work. Progress slowly.
Accumulation logic
Tirzepatide has a long half-life (~5 days). The overall effect builds gradually over several weeks at a constant dose. It is essential to progress in steps, allow the body to adapt, and avoid rapid increases that worsen digestive effects.
Signs to watch
- Positive: natural satiety, stable energy, proper digestion, gradual weight loss.
- To adjust: significant fatigue, dizziness / headaches, muscle cramps, persistent nausea, total loss of appetite.
Golden rule
Daily consistency matters more than occasional intensity. Adjustments are made based on data (weight, waist circumference, hunger, energy), not emotions.
Suggested adjustment scale (for guidance)
- Insufficient loss / plateau → move up to the next step (generally +2.5 mg) after about 4 weeks of tolerance.
- Loss too fast (> 1%/week) → maintain the dose or increase calories.
- Bothersome side effects → stay at the current step longer, or even step back down.
Usage tips
- Progress slowly: respect roughly 4-week steps before any dose increase.
- Inject on the same day each week to maintain stable levels.
- Optimal hydration and electrolyte intake (sodium, potassium, magnesium).
- Split meals: 4 to 6 small meals to limit nausea.
- Prioritize adequate protein intake (1.6 to 2.2 g/kg) to preserve lean mass.
- Keep a journal: symptoms, meals, hydration, weight, sleep.
Good to know / effects to watch
- Nausea (the most common effect, especially at the start of the protocol or after a dose increase).
- Diarrhea or constipation, bloating, early satiety, burping.
- Headaches, transient fatigue, significant loss of appetite.
- Most digestive effects ease within a few days to weeks as the body adapts.
- To monitor (consult a doctor if severe/persistent): repeated vomiting, intense abdominal pain, signs of pancreatitis, severe hypoglycemia (especially in combination with other treatments).
Storage
- Before reconstitution (lyophilized powder): refrigerated (2-8 °C), away from light; tolerates short periods at room temperature during shipping.
- After reconstitution: refrigerated (2-8 °C), typically use within ~4 weeks (28 days).
- Do not freeze, do not shake vigorously, avoid heat and direct light.
Contraindications
- Pregnancy and breastfeeding: avoid.
- Personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia type 2 (MEN 2): contraindication.
- History of pancreatitis; gallbladder disease; gastroparesis or severe GI disorder: caution.
- Interactions: hypoglycemia risk with insulin or sulfonylureas; delayed gastric emptying may reduce oral contraceptive efficacy and alter absorption of other drugs.
- Known hypersensitivity to tirzepatide or any excipient.
Possible synergistic combinations
Sodium, potassium, magnesium — prevent fatigue, cramps, and headaches.
Preserves lean mass during the caloric deficit.
Sources & references
Links to external sources (scientific databases, trial registries, authorities). RAL Peptides is not responsible for their content.
⚠ For research use only. NOT intended for use on humans or animals. The values shown are indicative and for informational purposes ; each person reacts differently. This guide does not replace medical advice — consult a healthcare professional if in doubt.