Fast Routes
Intravenous administration delivers the drug directly to the bloodstream with immediate effect. Intraosseous access offers similar speed when IV access fails, using the proximal tibia or humeral head. Endotracheal administration is no longer preferred and has been replaced by IV or IO.
Intermediate and Slow Routes
Intramuscular and subcutaneous injections absorb more slowly, with muscle absorbing faster because of greater blood flow. Intranasal delivery is a useful needle-free route for naloxone, midazolam, and fentanyl, using a mucosal atomizer. Sublingual and buccal routes bypass first-pass liver metabolism.
Choosing the Route
Match the route to urgency, patient condition, and drug properties. Shock patients absorb poorly from muscle and skin because of peripheral vasoconstriction. Always follow the six rights: patient, drug, dose, route, time, and documentation.