The route of administration determines how quickly a medication takes effect, how completely it is absorbed, how long it lasts, and how safely it can be given — which is why route is one of the foundational rights of medication administration. This lesson introduces the major routes the registered nurse uses every shift: oral, subcutaneous, intramuscular, intravenous, and topical, along with related enteral and mucosal routes. Each route reflects a trade-off between speed and safety. The oral route is the most common, safest, and least expensive, but it has the slowest, least predictable absorption because the drug must survive the gastrointestinal tract and first-pass liver metabolism. The subcutaneous route deposits small volumes into fatty tissue for slow, steady absorption, as with insulin and enoxaparin. The intramuscular route allows somewhat larger volumes and faster absorption into well-perfused muscle. The intravenous route places the drug directly into the bloodstream for the fastest, most complete effect — and therefore the least margin for error, since there is no way to retrieve a dose once given. Topical and transdermal routes act locally on skin...