retatrutide vs tirzepatide, one is approved and one isn't, why do people compare them like peers?
This comparison gets made constantly and the single most important fact usually gets buried.
Tirzepatide is approved for specific indications and has completed phase 3.
Retatrutide is investigational. Not through phase 3, not approved anywhere, for anything.
Mechanistically reta adds glucagon receptor agonism to the GLP-1/GIP combo, so it's a triple agonist. The glucagon part is counterintuitive (glucagon raises blood sugar) but the proposed rationale is energy expenditure rather than glycemic control alone.
The phase 2 results got a lot of attention and the reported weight reduction was large. Two things that matter enormously:
1. Phase 2 results routinely attenuate in phase 3. Bigger, longer, messier populations. This happens over and over and is the norm, not the exception. 2. Safety signals emerge with scale. A phase 2 population isn't big enough to characterize uncommon events.
Comparing them as if they were peers is the mistake I see most.