A 39-amino acid synthetic peptide that activates both GLP-1 and GIP receptors — the first dual incretin agonist. Its ~5-day half-life supports once-weekly subcutaneous administration with a broad dose titration range.
Tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. It is the first approved peptide to simultaneously activate both incretin receptor pathways — a pharmacological approach distinct from single-agonist GLP-1 compounds like semaglutide.
The 39-amino acid peptide is engineered with a C-20 fatty diacid moiety that enables albumin binding, extending its circulating half-life to approximately 120 hours (~5 days). While shorter than semaglutide's ~7-day half-life, this duration is sufficient for once-weekly dosing with acceptable peak-to-trough variation.
Tirzepatide's dose range is significantly broader than semaglutide's — spanning from 2.5 mg to 15 mg per week across the full titration. This wider range reflects the compound's dual-receptor pharmacology and allows for more granular dose optimization. Many protocols maintain users at intermediate doses (5–10 mg) rather than always escalating to the maximum.
Tirzepatide's dual agonism represents a distinct pharmacological approach compared to single-pathway GLP-1 compounds. Both receptor targets contribute to the compound's overall pharmacological profile.
Like semaglutide, tirzepatide activates GLP-1 receptors, potentiating glucose-dependent insulin secretion and slowing gastric emptying. The GLP-1 component is pharmacologically similar to established GLP-1 agonists.
The GIP component is what distinguishes tirzepatide. GIP (glucose-dependent insulinotropic polypeptide) is the other major incretin hormone. GIP receptor activation has been observed to influence adipose tissue metabolism and enhance beta-cell sensitivity in preclinical and clinical data.
The combination of GLP-1 and GIP receptor activation creates a pharmacological profile that differs from either pathway alone. Clinical trial data suggest the dual mechanism produces effects that exceed what either receptor activation achieves independently — a synergistic rather than simply additive interaction.
Tirzepatide's pharmacokinetic profile has been characterized across multiple Phase 2 and Phase 3 clinical trials, providing robust data on its absorption, distribution, and elimination parameters.
| Parameter | Value |
|---|---|
| Half-Life | ~120 hours (~5 days) |
| Bioavailability (SubQ) | ~95% |
| Time to Peak (Tmax) | ~48 hours (8–72 h range) |
| Duration of Activity | ~336 hours (~14 days) |
| Time to Steady State | 3.5–4 weeks |
| Route | Subcutaneous |
| Molecular Weight | ~4,810 Da |
Tirzepatide's 120-hour half-life is approximately 30% shorter than semaglutide's 161 hours. In practical pharmacokinetic terms, this means tirzepatide has a slightly wider peak-to-trough ratio within each weekly dosing interval. The trough level (day 7) is approximately 60–70% of the peak level (day 2), compared to semaglutide's ~70–80%.
The higher bioavailability (95% vs. semaglutide's 89%) means more of each injected dose reaches systemic circulation. Combined with the broader dose range, this gives tirzepatide protocols more pharmacokinetic flexibility for dose adjustment.
Tirzepatide reaches steady state faster (~3.5 weeks vs ~4.5 weeks) due to its shorter half-life, but has slightly more intra-week level fluctuation. Both compounds maintain therapeutically relevant levels throughout the 7-day dosing interval at steady state.
Tirzepatide follows a gradual dose titration. The 6-step escalation schedule is more granular than semaglutide's, with each step lasting approximately 4 weeks.
Unlike semaglutide where most protocols escalate toward the maximum dose, tirzepatide's wider dose range means many protocols plateau at intermediate levels (5–10 mg/week). The broader range allows for more individualized dose optimization based on observed response at each titration step.
Pre-filled pens (branded tirzepatide) do not require reconstitution. Compounded lyophilized tirzepatide requires the following preparation.
Compounded tirzepatide vials vary in total content — common sizes include 5 mg, 10 mg, 15 mg, and 30 mg. Note the exact mg on the vial label before proceeding.
Clean the rubber stoppers on both the tirzepatide vial and bacteriostatic water vial with alcohol swabs. Allow to air dry for 10–15 seconds.
Use the Milligram calculator for precise volumes. Example: a 30 mg vial + 3 mL bac water = 10 mg/mL. For a 5 mg weekly dose, draw 0.5 mL (50 units on a U-100 insulin syringe).
Draw the calculated volume of bacteriostatic water. Insert the needle into the tirzepatide vial and release the water slowly against the inside glass wall. Do not jet directly onto the powder cake.
Gently swirl the vial until the powder is completely dissolved into a clear solution. Tirzepatide may take slightly longer to dissolve than smaller peptides. Never shake the vial aggressively.
Store at 2–8°C. Reconstituted tirzepatide with bacteriostatic water is generally stable for up to 28 days refrigerated. Write the reconstitution date and concentration on the vial.