Retatrutide, tirzepatide, semaglutide: how the three differ
A plain-language comparison of the three GLP-1 class molecules we carry — receptor targets, titration rhythm, cold-chain handling and what each pen actually contains.
22 July 2026 · 8 min read
The three molecules people ask about most sit on the same family tree but pull different levers. Here is the short version, with links to each item in the peptide library.
Semaglutide — the single agonist
Semaglutide acts on the GLP-1 receptor alone. It is the most studied of the three and the most familiar titration pattern: small starting dose, slow step-ups, weekly cadence. We stock it as 4mg and 12mg cartridges.
If needles are the objection rather than the molecule, Foundayo is the oral route with no cold chain to manage.
Tirzepatide — dual agonist
Tirzepatide engages both GIP and GLP-1 receptors. Research literature reports a stronger effect on appetite signalling than single agonism, and users typically describe a smoother appetite curve between doses.
Retatrutide — triple agonist
Retatrutide adds a glucagon receptor to the same pair. It is the newest of the three and the most active area of published research. It is also the one where careful, unhurried titration matters most.
Cagrilintide sits slightly aside from all three — an amylin analogue often studied alongside semaglutide rather than instead of it.
What arrives, and how
Every cartridge is ready-mixed, sealed and batch-coded — no reconstitution, no vials, no guesswork. They ship cold, in an insulated mailer with a cold pack, Monday to Saturday. The handling detail is on our shipping page, and batch documents live under certificates.
New to the format? The starter setup guide covers pens, needles and clicks.
