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Tirzepatide

GIP / GLP-1 dual receptor agonist

Also known as: Mounjaro, Zepbound

Tier 1, Approved, characterised

Approved by at least one major regulator for a defined indication, with published human pharmacokinetics and a prescribing label. Well-characterised does not mean risk-free, read the label warnings.

Half-life
5.0 days · human data · subcutaneous

Approximately 5 days, supporting weekly dosing. Median tmax 24 h (range 8-72 h). Absolute bioavailability ~80%. Steady state reached after ~4 weeks of weekly dosing.

Model a dosing schedule →
Dosing
2500 - 15000 mcg

Label doses 2.5 mg (starting) to 15 mg maximum. 2.5 mg is a tolerability step, not a maintenance dose.

Titration
Start 2.5 mg weekly x4 weeks, increase to 5 mg. Thereafter increase in 2.5 mg increments after at least 4 weeks at the current dose. Maximum 15 mg weekly.
Frequency
Once weekly
Timing
Any time of day, with or without food; same day each week.
Regulatory status
FDA approved (type 2 diabetes as Mounjaro; chronic weight management as Zepbound).
Evidence base
human clinical · confidence: high
Storage

Reconstituted: Commercial pens/vials: refrigerate 2-8°C. See label for permitted room-temperature window.

Safety

BOXED WARNING: thyroid C-cell tumours in rodents; contraindicated with personal or family history of medullary thyroid carcinoma or MEN 2. Risks include pancreatitis, gallbladder disease, hypoglycaemia when combined with insulin/sulfonylureas, and acute kidney injury from dehydration. Delays gastric emptying, which is largest after the first dose and may affect absorption of oral medications.

Sources