Which type of injection is administered into the fatty tissue beneath the skin?

The correct answer is subcutaneous injection, which is specifically administered into the fatty tissue located beneath the skin. This method allows for the slow absorption of medications into the bloodstream, making it ideal for substances that require gradual release, such as insulin or some vaccines.

Subcutaneous injections are typically given using a short needle at a 45 to 90-degree angle, depending on the patient's body type, and are often administered in areas such as the abdomen, thigh, or back of the upper arm where there is a sufficient layer of fat. This route is preferred for its ease of administration and comfort for the patient.

Intravenous injections involve delivering medication directly into the bloodstream via a vein, allowing for rapid effect, which is not what occurs with subcutaneous injections. Intramuscular injections are delivered deep into a muscle, providing a faster absorption time than subcutaneous injections but requiring a different technique and equipment. Intradermal injections are given into the dermal layer of the skin, primarily for allergy testing or tuberculosis screening, which again is distinct from the subcutaneous route. Therefore, the subcutaneous route is uniquely suited to specific medications that benefit from slower absorption.