Retatrutide Glossary

Short, plain definitions of the words that come up most.

Bacteriostatic water (BAC water)

Sterile water with a small amount of benzyl alcohol that slows bacterial growth, used to dissolve freeze-dried powder in a vial.

GIP

Glucose-dependent insulinotropic polypeptide, a gut hormone released after eating that helps the body release insulin. Tirzepatide and retatrutide both act on its receptor.

GLP-1

Glucagon-like peptide 1, a gut hormone that increases fullness, slows stomach emptying and helps control blood sugar. Semaglutide acts only on this receptor.

Glucagon

A hormone made by the pancreas that acts mainly on the liver. Retatrutide is unusual in also activating the glucagon receptor.

GLP-3

An informal nickname for retatrutide used online. It is not an official drug class or hormone name.

HbA1c

A blood test that reflects average blood sugar over roughly the previous three months, used to track diabetes.

LY3437943

Eli Lilly's development code for retatrutide.

MASLD and MASH

Metabolic dysfunction-associated steatotic liver disease and its inflammatory form, metabolic dysfunction-associated steatohepatitis. These are the current names for what used to be called NAFLD and NASH.

Phase 2 and Phase 3

Stages of clinical testing. Phase 2 trials test doses and early effectiveness in a few hundred people; Phase 3 trials confirm benefits and safety in thousands before a company can apply for approval.

Placebo

An inactive treatment given to a comparison group in a trial so the real effect of the medicine can be measured.

Reconstitution

Adding liquid, usually bacteriostatic water, to a freeze-dried powder so it can be drawn into a syringe.

Subcutaneous injection

An injection into the fat layer just under the skin, usually in the stomach, thigh or upper arm.

Titration

Starting a medicine at a low dose and raising it in steps, which gives the body time to adjust and reduces side effects.

Topline results

The first headline results a company announces from a trial, before the full data is published in a journal.

Triple agonist

A single molecule that activates three different hormone receptors. Retatrutide activates the GIP, GLP-1 and glucagon receptors.

U-100 syringe

An insulin syringe marked so that 100 units equal 1 millilitre.