What route of medication administration is characterized by delivery into the skin layers?

Intradermal administration involves delivering medication into the layers of the skin, specifically the dermis, which is situated just beneath the outer layer, or epidermis. This route is often used for allergy testing or vaccinations, such as the tuberculin skin test (Mantoux test). The technique typically involves a very small needle that creates a small bleb under the skin.

Choosing intradermal over the other routes is appropriate because subcutaneous administration delivers medication into the fatty tissue just beneath the skin, while intramuscular administration involves injecting medication deep into a muscle. Intravenous administration entails delivering medication directly into the bloodstream through a vein, allowing for immediate effect and high bioavailability. Each of these other routes involves different depths and techniques, making intradermal distinct in its application and purpose.