Tirzepatide

Definition

Tirzepatide is a 39-amino-acid synthetic peptide that activates both the GIP and GLP-1 receptors, the first dual incretin agonist approved in the United States; it is marketed for type 2 diabetes and for chronic weight management.

Engaging two incretin receptors rather than one produces larger average weight reductions than GLP-1 agonism alone, at the cost of a similar gastrointestinal tolerability profile.

Evidence

In SURMOUNT-1, 2,539 adults with obesity received weekly tirzepatide or placebo for 72 weeks; mean weight change was −15.0 percent at 5 mg, −19.5 percent at 10 mg, and −20.9 percent at 15 mg, against −3.1 percent with placebo ^[1].

As with semaglutide, the open questions are durability and long-term safety in broad use; efficacy against placebo is settled.

Lawful access

The approved products are the lawful supply route. The FDA declared the tirzepatide shortage resolved in October 2024, ending shortage-based compounding; the April 2026 proposal to exclude it from the 503B bulks list closes the outsourcing route, and patient-specific 503A compounding requires documented clinical need ^[2].

Telehealth programs in the supply panel provide prescriber-led GLP-1 treatment; molecule and formulation vary by provider and should be confirmed on the provider's own site.

Related molecules

The class comparison with semaglutide is drawn on the GLP-1 receptor agonists page; the approved status page lists the index's approved molecules.