Understanding Medication Routes
The route of medication administration affects how quickly the drug takes effect, how much of the drug reaches its target, and the potential side effects. Choosing the correct route is as important as choosing the correct medication. EMS providers must understand the advantages, disadvantages, and indications for each route, as this knowledge is tested extensively on the NREMT exam and is essential for safe field practice.
Key concepts include onset of action (how quickly the drug begins working), bioavailability (the percentage of the administered dose that reaches systemic circulation), and duration of action (how long the effects last). These factors vary dramatically by route: IV medications have nearly immediate onset and 100% bioavailability, while oral medications may take 30 to 60 minutes to take effect and have variable bioavailability due to first-pass metabolism in the liver.
Routes Available to EMTs
Oral (PO)
The oral route is the simplest but slowest route. The patient must be conscious, able to swallow, and have no nausea or vomiting. Onset is typically 30 to 60 minutes. EMT-level oral medications include aspirin (chewed for faster absorption in suspected ACS), oral glucose (for hypoglycemia in conscious patients), and activated charcoal (for certain poisonings per medical direction). Always verify the patient's ability to protect their airway before administering oral medications.
Sublingual (SL)
Medications placed under the tongue are absorbed directly into the bloodstream through the sublingual mucosa, bypassing first-pass metabolism. Onset is 1 to 5 minutes. Nitroglycerin is the primary sublingual medication in EMS, administered as a 0.4 mg tablet or spray for chest pain (after confirming systolic BP above 100 and no recent phosphodiesterase inhibitor use).
Inhaled
Inhaled medications are delivered directly to the lungs via nebulizer or metered-dose inhaler (MDI). This route provides rapid onset (1 to 5 minutes) with minimal systemic side effects. Albuterol is the primary inhaled medication in EMS, administered via nebulizer (2.5 mg) or MDI (typically 4 to 8 puffs with spacer) for bronchospasm.
Routes Available to Paramedics
Intramuscular (IM)
IM injections are administered into muscle tissue (deltoid, vastus lateralis, or gluteus). Onset is 5 to 15 minutes. Common IM medications include epinephrine (for anaphylaxis), glucagon (for hypoglycemia when IV access is not available), and midazolam (for seizures). The autoinjector (EpiPen) is designed for IM injection into the lateral thigh.
Intravenous (IV)
IV administration provides the fastest onset (seconds to minutes) and allows precise dose titration. Virtually all paramedic-level medications can be administered IV. The disadvantage is the requirement for IV access, which may be difficult in patients with poor veins, dehydration, or shock.
Intranasal (IN)
The intranasal route uses a mucosal atomizer device (MAD) to deliver medication as a fine spray into the nasal mucosa. Onset is 2 to 5 minutes. Commonly used for naloxone (for opioid overdose, 2 mg per nostril), midazolam (for seizures), and fentanyl (for pain management). The IN route is particularly valuable when IV access is difficult or dangerous (combative patients, pediatric patients).
Intraosseous (IO)
IO access provides a route to the vascular system through the bone marrow. It is used when IV access cannot be established in critically ill patients (cardiac arrest, severe shock). Common insertion sites include the proximal tibia and the proximal humerus. Any medication or fluid that can be administered IV can be administered IO. Onset is comparable to IV administration. IO access is typically established using a battery-powered drill device (EZ-IO) with the appropriate needle size for the patient.