Semaglutide, Tirzepatide, Retatrutide: The GLP-1 Family Side by Side

Metabolic research is dominated by the GLP-1 family right now. Three compounds lead the discussion: semaglutide, tirzepatide and retatrutide. The quickest way to tell them apart is to count the receptors each one activates.

Below we set out those receptors, put the three compounds next to each other, and state plainly which are licensed medicines and which is still under clinical study.

Three receptors to know

The discussion centres on three receptors in the gut and metabolic system. GLP-1 and GIP belong to the incretin system. Research links them with lower appetite and slower gastric emptying. Glucagon is linked with energy expenditure. In general, a molecule that engages more of these receptors is described as having a wider metabolic effect.

One, two or three targets

Semaglutide, the molecule in Ozempic and Wegovy, is a single agonist. It activates GLP-1 and nothing else. Tirzepatide, the molecule in Mounjaro, is a dual agonist covering GLP-1 and GIP. Retatrutide is a triple agonist covering GLP-1, GIP and glucagon. That third target is why it is often called a “next-generation” candidate. It has also been linked with the biggest weight changes recorded in its trials.

The state of the evidence

In Phase 2, retatrutide produced large reductions in body weight. Phase 3 trials were still running, and their first readouts began to arrive in December 2025. Retatrutide is the youngest of the three compounds and has the least research behind it. So its early results look the strongest, yet its evidence base is the smallest. Read trial numbers as research background, not as results anyone should anticipate.

Further resources

The retatrutide product page lists the compound's specification. Our calculator handles reconstitution arithmetic. Whatever the work, check the CoA for material quality first.