🚧 Under construction — VoTechWorks is being built. A free tech program — complimentary, as our commitment to get America working.
voTechWorksGrade 13 · a vocational technology learning center, by urbanicity
newSchoolWorks.com › VoTechWorks › Health & Personal Services › EMT / Paramedic › Pharmacology for Emergency Medical Services › Lesson 3
HLT-EMT39-05 · Lesson 3 · 22 clock hours · demo

Routes of Administration: Anatomy, Technique, and Drug Delivery Principles

Objective. Students will identify the anatomical landmarks, advantages, disadvantages, and absorption characteristics of each medication route used in prehospital EMS, including IV, IO, IM, SQ, SL, IN, ET, and oral routes.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Routes of Administration: Anatomy, Technique, and Drug Delivery Principles

Every medication a paramedic gives must travel from the point of administration into the bloodstream and then to target tissues. The path it takes — the route of administration — determines how quickly the drug works, how reliably it is absorbed, and what risks it carries. Choosing the right route is a clinical decision that balances the patient's condition, vascular access, available equipment, and time.

Intravenous (IV) Route

The IV route delivers medication directly into a peripheral vein, bypassing absorption entirely. Onset is fastest — typically within one circulation time. Common peripheral sites include the antecubital fossa, forearm, and dorsum of the hand. The cephalic, basilic, and median cubital veins are reliable landmarks. Select the largest, straightest vein appropriate to the situation. Catheter gauge matters: larger-bore catheters (14–16 gauge) support rapid fluid delivery; smaller gauges (18–22 gauge) are suitable for routine medication administration.

Safety points: Confirm patency before every push by checking for blood return and absence of infiltration. Never infuse vesicant or high-concentration drugs through a compromised line. Maintain aseptic technique to prevent catheter-related bloodstream infection.

Intraosseous (IO) Route

When IV access fails or is too slow to establish — particularly in cardiac arrest, status epilepticus, or severe shock — IO access provides a non-collapsible vascular channel through the medullary cavity of a long bone. Drug onset and distribution are comparable to IV. Approved prehospital sites include the proximal tibia (flat anteromedial surface, approximately two finger-widths below the tibial tuberosity), the distal tibia (medial surface above the medial malleolus), and the proximal humerus. IO access requires a powered or manual IO drill and appropriate needle length based on tissue depth.

Safety points: Confirm placement by aspirating marrow and flushing with saline — watch for swelling suggesting extravasation. IO access is a temporary bridge; convert to IV as soon as practical. Avoid sites with fractures, previous IO attempts in the same bone within 24 hours, or overlying infection.

Intramuscular (IM) Route

IM injection delivers medication into muscle tissue, where a rich capillary network supports absorption. Onset is slower than IV/IO (typically several minutes) but faster than subcutaneous. Preferred prehospital sites are the deltoid (small-volume injections, 1–2 mL maximum) and the vastus lateralis (mid-outer thigh, useful in infants and when deltoid is inaccessible). Use a 1–1.5 inch needle (21–23 gauge) for most adults; adjust for obesity or pediatric patients. Aspirate per local protocol; current evidence and many protocols no longer require aspiration for most IM sites.

Safety points: Avoid the gluteal region prehospitally due to risk of sciatic nerve injury. Rotate sites for repeated injections. Do not inject into edematous or poorly perfused tissue, as absorption will be erratic.

Subcutaneous (SQ) Route

SQ injection places medication into the fatty layer just beneath the skin, where absorption is slower and more sustained than IM. The anterior thigh and outer upper arm are common sites. Use a short needle (3/8–5/8 inch, 25–27 gauge) at a 45-degree angle. Volume per site is generally limited to 1 mL or less.

Safety points: Avoid SQ in patients with poor perfusion (shock, hypothermia) because absorption becomes unpredictable. Epinephrine for anaphylaxis is now more commonly given IM for faster absorption.

Sublingual (SL) Route

SL medications dissolve under the tongue and absorb directly into the sublingual venous plexus, bypassing first-pass hepatic metabolism. Onset is rapid — often within minutes. The patient must be conscious, cooperative, and able to hold the drug in place. Nitroglycerin is the classic prehospital SL drug.

Safety points: Confirm the patient is not hypotensive before administering SL nitroglycerin. Instruct the patient not to swallow or chew the tablet/spray.

Intranasal (IN) Route

IN administration delivers atomized medication onto the highly vascular nasal mucosa. A mucosal atomizer device (MAD) is attached to a syringe and converts liquid to fine droplets. Absorption is rapid and avoids IV access — valuable for pediatric patients or combative subjects. Naloxone and midazolam are commonly given IN in prehospital care.

Safety points: Divide doses greater than 1 mL total between both nares to improve absorption. Nasal trauma, congestion, or active epistaxis reduces drug uptake.

Endotracheal (ET) Route

Certain drugs can be instilled through an endotracheal tube when no vascular access exists. The mnemonic NAVEL (Naloxone, Atropine, Vasopressin, Epinephrine, Lidocaine) lists agents with some ET evidence. Doses given ET are generally higher than IV doses, diluted in saline and followed by several ventilations to distribute the drug.

Safety points: ET is a last resort — IO access is preferred over ET when vascular access is unavailable. Drug absorption via ET is less reliable and more variable than IV or IO.

Oral (PO) Route

Oral administration is rarely used in active prehospital emergencies because onset is slow (30 minutes or more), and patients are often unable to swallow safely. Activated charcoal and glucose gel are examples of orally administered EMS agents. The oral route is subject to first-pass metabolism, which reduces bioavailability of many drugs.

Safety points: Never give oral medications to unconscious patients or those with an unprotected airway — aspiration risk is significant.

Comparing Routes: A Clinical Summary

When choosing a route, consider: (1) Speed needed — cardiac arrest demands IV or IO immediately; (2) Patient condition — poor perfusion impairs IM and SQ absorption; (3) Available access — failed IV shifts the decision to IO or IN; (4) Drug formulation — not every drug can be given by every route. Always follow your local EMS protocols and medical director guidance.

Key terms9

BioavailabilityThe fraction of an administered drug dose that reaches systemic circulation in an active form; IV administration gives 100% bioavailability because absorption is bypassed entirely.
First-pass metabolismThe reduction in drug concentration that occurs when an orally absorbed drug passes through the liver before entering systemic circulation, lowering the effective dose.
Intraosseous (IO) accessA route of vascular access that delivers fluids and medications into the medullary cavity of a bone; used when IV access cannot be rapidly established.
VesicantA drug or solution capable of causing severe tissue damage and necrosis if it extravasates outside a vein into surrounding tissue.
Mucosal atomizer device (MAD)A syringe attachment that converts liquid medication into fine droplets for intranasal delivery, maximizing contact with the nasal mucosa for rapid absorption.
ExtravasationThe unintended leakage of IV or IO fluid and medication into surrounding tissue, which can cause pain, swelling, and tissue injury.
NAVEL mnemonicA memory aid listing medications that can be administered via the endotracheal route: Naloxone, Atropine, Vasopressin, Epinephrine, and Lidocaine.
Sublingual venous plexusThe dense network of veins beneath the tongue that rapidly absorbs sublingual medications directly into systemic circulation, bypassing first-pass metabolism.
Vastus lateralisThe muscle of the mid-outer thigh; a preferred intramuscular injection site in infants, young children, and adults when the deltoid is inaccessible.
In class: Instructor demonstration on anatomical models and task trainers of each route; students annotate a body-diagram worksheet labeling preferred injection sites, needle gauge and length, and expected onset time. · Video analysis: students watch a recorded paramedic skill video for IV and IO access, then complete a structured observation checklist identifying correct and incorrect technique. · Think-pair-share: given four patient scenarios (pediatric, obese adult, burned extremity, arrest), student pairs select and justify the best administration route and share reasoning with the class.
Materials: IV/IO task trainers, anatomical diagrams, body-diagram worksheet, observation checklist, video recording, needle/catheter samples (capped, for demonstration), EMS pharmacology textbook
Check: Oral question-and-answer: instructor presents five patient scenarios; student must correctly identify the appropriate route and rationale for each. Pass mark: correct route with full justification on 4 of 5 scenarios.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Pharmacology and Medication Administration
1. A paramedic attempts IV access twice on a patient in cardiac arrest and fails. Which route should be established next according to current EMS practice?
Pharmacology and Medication Administration
2. Which of the following best explains why the oral route is rarely used in active prehospital emergencies?
Pharmacology and Medication Administration
3. A paramedic is administering intranasal naloxone to an unresponsive adult. The calculated dose requires 2.5 mL total. What is the correct technique?
Pharmacology and Medication Administration
4. A patient in severe anaphylaxis is in compensated shock with a BP of 88/60 mmHg. The paramedic plans to give epinephrine. Why is the intramuscular route preferred over subcutaneous in this situation?
Pharmacology and Medication Administration
5. When confirming IO needle placement in the proximal tibia, which finding is most reassuring that the needle is correctly positioned in the medullary cavity?
Pharmacology and Medication Administration
6. A paramedic needs to give a small-volume IM injection to a conscious adult patient with no IV access. Which site is most appropriate in the prehospital setting?
Pharmacology and Medication Administration
7. A paramedic administers sublingual nitroglycerin to a patient with chest pain. Before administration, which assessment finding is most critical to verify?
Pharmacology and Medication Administration
8. During a pediatric seizure, IV access cannot be established. Which combination of route and drug is most appropriate for rapid benzodiazepine delivery in the prehospital setting?
Record this lesson on my transcript. Sign in with your key and enrollment email to record lessons (enroll free if you have no key). This page stays open to read and practise.
← Previous lessonProgram planNext lesson →