route of administration

The route of administration is simply how a medicine gets into or onto the body: swallowed, injected, breathed in, applied to skin, placed under the tongue, or inserted into the rectum. Each route is a different door into the body, with its own speed, convenience and limits.

The route profoundly shapes both the dosage form and the drug's fate. An oral tablet must survive stomach acid and pass the liver's first-pass metabolism, which can destroy much of the dose; an intravenous injection delivers the full dose straight into the blood but demands sterility and a clinician. The lungs, skin, nose and eyes each offer their own opportunities and constraints.

Choosing a route balances onset, bioavailability, safety and patient acceptability. The oral route is preferred for being painless and convenient, but is unsuitable for drugs destroyed in the gut or needed instantly in an emergency, where injection or inhalation wins.