Routes of administration

A route of administration is the path a medication takes into the body. Routes are broadly grouped as enteral (through the gastrointestinal tract — oral, sublingual, buccal, rectal), parenteral (bypassing the GI tract by injection — intravenous, intramuscular, subcutaneous, intradermal), and topical or other routes applied to a body surface (skin creams, transdermal patches, eye and ear drops, nasal sprays, and inhalation into the lungs).

The route shapes both the speed and extent of drug action. Oral dosing is the most common and convenient, but absorbed drug passes through the liver before reaching circulation — the first-pass effect — which can inactivate much of the dose. Sublingual tablets like nitroglycerin absorb directly into the bloodstream and bypass first-pass metabolism, which is why they act within minutes. Intravenous administration delivers 100 percent bioavailability immediately, intramuscular and subcutaneous injections absorb more gradually, and transdermal patches release drug slowly for extended, steady effect.

Choosing a route depends on the drug's chemistry, the desired onset, and the patient: a vomiting patient may need a rectal or parenteral form, an unconscious patient cannot swallow tablets, and inhaled medications target the lungs directly for asthma while minimizing systemic exposure. Each route also carries handling implications — parenteral products must be sterile, and certain forms (enteric-coated or extended-release tablets) must not be crushed.

The PTCE tests routes of administration alongside dosage forms and special handling requirements, while the CCMA exam covers administering medications by each route as part of clinical duties. Know the enteral versus parenteral distinction, the first-pass effect, and which routes act fastest.