Which route of medication administration involves injecting directly into the muscle?

The route of medication administration that involves injecting directly into the muscle is known as intramuscular (IM) injection. This method is particularly effective for delivering medications that need to be absorbed quickly into the bloodstream because muscles have a rich blood supply. When a medication is injected into the muscle tissue, it allows for a more rapid onset of action compared to subcutaneous injections, which are given into the fatty layer beneath the skin.

Intramuscular injections are commonly used for vaccines, hormones, and other medications that require deeper penetration into the body to ensure appropriate absorption and efficacy. This route is also advantageous for larger volumes of medication, as well as for formulations that are intended for slow release over time.

In contrast, intravenous administration involves injecting directly into a vein, which provides immediate delivery into the bloodstream. Subcutaneous injections are administered into the tissue layer between the skin and muscle, and intradermal injections are given just below the epidermis, into the dermal layer of the skin. Each of these routes serves different purposes and is chosen based on the specific medication, its intended effect, and how quickly it is required to act.