A quiet analytical research laboratory at night, racks of glass vials along a dim bench.

Tirzepatide

Tirzepatide is an approved once-weekly injectable peptide that activates both GIP and GLP-1 receptors. Like semaglutide, it relies on a fatty acid chain and albumin binding for a multi-day half-life, and there is no approved oral form. Vegalab does not make or sell tirzepatide.

Molecule and mechanism

Tirzepatide is a 39-amino-acid linear peptide of about 4.8 kDa based on the GIP sequence, with a C20 fatty diacid attached through a linker to lysine 20. It binds albumin, giving a half-life of about five days. It is an agonist at the GIP receptor with lower, biased agonism at the GLP-1 receptor. Its effects on weight exceed those of selective GLP-1 agonists in head-to-head and cross-trial comparisons, though the contribution of GIP agonism is still debated.

Approved products

FDA approved tirzepatide as Mounjaro for type 2 diabetes in 2022 and as Zepbound for chronic weight management in 2023, with a later approval for moderate to severe obstructive sleep apnea in adults with obesity. The EMA has authorized Mounjaro. Tirzepatide is not on the WADA Prohibited List. FDA has issued warnings about unapproved and counterfeit tirzepatide sold online. Vegalab does not supply any tirzepatide product. Compounded versions are not FDA-approved products.

Delivery characteristics

Tirzepatide is given by weekly subcutaneous injection from prefilled pens or vials. At nearly 5 kDa, with multiple protease-sensitive sites and an acyl chain, it faces the same oral barriers as semaglutide: gastric pepsin, pancreatic proteases, the mucus layer and tight epithelial junctions. Its larger size makes passive permeation even less favorable. Lilly's oral incretin strategy uses small molecules such as orforglipron instead. Transdermal and pulmonary routes face similar size barriers.

What this means for delivery research

Tirzepatide illustrates that in the incretin field, the oral route is being pursued mainly with small molecules rather than oral peptide formulations. Oral delivery of a dual agonist peptide remains a research question. For delivery partners, dual and triple agonists raise an additional requirement: any formulation must preserve the intended ratio of receptor activities, which can shift if part of the peptide is degraded or modified. Analytical methods for intact peptide and degradation products therefore matter as much as release data. That makes tirzepatide a useful reference for method development.

Key facts

In SURMOUNT-1, weekly tirzepatide 15 mg produced a mean 20.9% body weight reduction at 72 weeks versus 3.1% with placebo (Jastreboff et al. 2022, N Engl J Med 387:205)
Tirzepatide half-life is approximately 5 days, supporting once-weekly dosing (FDA label, Mounjaro 2022)
Zepbound was approved by FDA for chronic weight management in adults with obesity or overweight with a weight-related condition (FDA label, Zepbound 2023)

How our delivery technology applies

Tirzepatide is a reference molecule for feasibility work, not a product target. Larger acylated peptides test every layer of an oral delivery system: acid shielding, protease resistance, mucus penetration and epithelial permeation. Vegalab's multi-layer particles let those functions be assigned to separate layers and measured separately in vitro. Human oral bioavailability for peptides of this size is expected to be very low, and our program is exploratory.

Discuss peptide delivery feasibility studies with Vegalab's partnership team.