Subcutaneous Injection
Definition
An injection into the fatty layer between the skin and the muscle, from which the drug is absorbed slowly and steadily into the blood.
Subcutaneous Injection
A subcutaneous injection delivers medicine into the layer of fatty tissue (adipose tissue) just under the skin and above the muscle. It is widely used for biologics, peptides and proteins, which would be broken down in the gut if swallowed. The tissue under the skin acts as a depot, so the drug is absorbed slowly and steadily into the blood through nearby capillaries. Common sites are the abdomen, thigh and upper arm, and most people can be taught to inject themselves at home.
Injection under the skin is the standard route for incretin-based drugs, including retatrutide. Retatrutide is made for a once-weekly injection. Slow absorption from the depot, combined with the peptide’s engineered long half-life, keeps drug levels effective across the whole week. In clinical trials, participants injected retatrutide themselves with prefilled syringes or autoinjectors, and injection site reactions were usually mild and uncommon.
Compared with injection into a vein, this route has practical advantages. You do not need a health professional for each dose, the schedule can fit your routine, and you avoid the sharp peaks and troughs in drug levels that come with a single intravenous dose. That makes a once-weekly injection under the skin easy on patients and helps people stay on treatment long term, which matters for chronic conditions like type 2 diabetes and obesity where treatment may last indefinitely.