What is the route of medication administration that involves injecting under the skin?

The route of medication administration that involves injecting under the skin is subcutaneous. This method involves delivering the medication into the fatty tissue layer just beneath the skin, allowing for slow and steady absorption into the bloodstream. Subcutaneous injections are commonly used for administering vaccines, insulin, and heparin.

The technique involves using a short needle to penetrate the skin and deposit the medication in areas such as the outer aspect of the upper arms, abdomen, or thighs, where there are adequate fatty tissue deposits. This method is preferred for certain medications because it is less invasive and can be performed quickly by healthcare professionals or even by patients themselves with appropriate training.

In contrast, intramuscular injections require penetration into muscle tissues, which has a different absorption profile and is used for medications requiring rapid onset. Intradermal injections are administered directly into the dermis layer of the skin, primarily for allergy tests and tuberculosis screening. Intravenous injections involve delivering medication directly into the bloodstream through a vein, providing immediate effects but requiring more technical skills and equipment. Thus, subcutaneous injections are the correct choice for the described route.