Route of Administration

The path by which a drug is delivered into the body, fundamentally determining its rate and extent of absorption, onset of action, and bioavailability. Routes are classified as enteral (oral, sublingual, rectal), parenteral (intravenous, intramuscular, subcutaneous), or topical/transdermal. Selection depends on drug properties, clinical urgency, patient compliance, and therapeutic goals.

Examples

• IV bolus for immediate 100% bioavailability (emergency)
• Oral route for chronic daily dosing (most common)
• Intrathecal methotrexate for CNS leukemia (bypasses BBB)