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👩‍⚕️Foundations of Nursing Practice

Medication Administration Routes

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Why This Matters

Medication administration is one of the most fundamental—and most tested—nursing competencies you'll encounter. Understanding routes isn't just about memorizing where a drug goes; you're being tested on your ability to select the appropriate route based on patient condition, drug characteristics, and therapeutic goals. Every route decision involves weighing onset of action, bioavailability, patient status, and safety considerations.

The NCLEX and your nursing exams will challenge you to think critically about why one route is preferred over another in specific clinical scenarios. A patient who's vomiting can't take oral meds—what's your alternative? A patient needs immediate drug effects in an emergency—which route delivers? Don't just memorize the routes—know what clinical situations call for each and understand the pharmacokinetic principles that make each route unique.


Enteral Routes: Through the GI Tract

Enteral administration delivers medications through the gastrointestinal system. These routes rely on absorption through the GI mucosa and are subject to first-pass metabolism in the liver, which can significantly reduce the amount of active drug reaching systemic circulation.

Oral Administration

  • Most common and convenient route—includes tablets, capsules, liquids, and sustained-release formulations
  • First-pass metabolism reduces bioavailability; absorption affected by food, gastric pH, and GI motility
  • Contraindicated in patients who are NPO, vomiting, unconscious, or have impaired swallowing

Rectal Administration

  • Alternative enteral route when oral is contraindicated—medication absorbed through rectal mucosa
  • Bypasses upper GI tract but still subject to partial first-pass metabolism; unpredictable absorption rates
  • Dual purpose—provides local effects (hemorrhoid treatment) or systemic effects (fever reduction with acetaminophen suppositories)

Compare: Oral vs. Rectal—both are enteral routes subject to some first-pass metabolism, but rectal bypasses the upper GI tract and works for patients who can't swallow or are vomiting. If an exam question presents an unconscious patient needing fever reduction, rectal is your answer.


Mucosal Routes: Rapid Absorption, Bypassing First-Pass

These routes deliver medication through highly vascularized mucous membranes, allowing drugs to enter the bloodstream directly. By bypassing the GI tract and liver, these routes avoid first-pass metabolism and achieve faster onset.

Sublingual Administration

  • Placed under the tongue for rapid absorption through the sublingual mucosa into systemic circulation
  • Bypasses first-pass metabolism—ideal for drugs like nitroglycerin that would be extensively metabolized if swallowed
  • Quick onset (1-2 minutes); patient must not swallow medication or drink water until dissolved

Intranasal Administration

  • Absorbed through nasal mucosa directly into bloodstream—highly vascularized tissue enables rapid uptake
  • Bypasses GI tract and first-pass metabolism—used for naloxone (Narcan) in opioid overdose emergencies
  • Non-invasive alternative to injection; also used for migraine medications and certain vaccines

Inhalation

  • Delivered directly to respiratory tract via metered-dose inhalers (MDIs), dry powder inhalers (DPIs), or nebulizers
  • Rapid onset for respiratory conditions—bronchodilators reach target tissue within minutes
  • Technique-dependent effectiveness—improper use significantly reduces drug delivery; always assess and teach proper technique

Compare: Sublingual vs. Intranasal—both bypass first-pass metabolism for rapid systemic effects, but sublingual requires patient cooperation (no swallowing), while intranasal can be administered to unresponsive patients (think naloxone in overdose). Know which scenarios call for each.


Parenteral Routes: Injection-Based Delivery

Parenteral routes bypass the GI tract entirely through injection. These routes offer predictable absorption and are essential when oral administration is impossible or when precise drug levels are required.

Intravenous Administration

  • Direct bloodstream delivery—100% bioavailability with immediate onset of action
  • Precise control over drug concentration; allows titration and is essential for emergency situations and critical care
  • Highest risk route—requires sterile technique; monitor for complications including phlebitis, infiltration, and air embolism

Intramuscular Injection

  • Injected into muscle tissue—good blood supply allows faster absorption than subcutaneous
  • Appropriate sites: deltoid (small volumes), vastus lateralis (infants), ventrogluteal (preferred for adults), dorsogluteal (avoid if possible)
  • Accommodates larger volumes (up to 3-5 mL depending on site) and depot formulations; common for vaccines and certain antibiotics

Subcutaneous Injection

  • Injected into adipose tissue just beneath the dermis—slower, more sustained absorption than IM
  • Ideal for medications requiring gradual release—insulin, heparin, and certain biologics
  • Common sites: abdomen (fastest absorption), thigh, upper arm; rotate injection sites to prevent lipodystrophy

Compare: IV vs. IM vs. Subcutaneous—all bypass first-pass metabolism, but onset differs dramatically: IV is immediate, IM is moderate (10-30 minutes), and subcutaneous is slowest. Volume capacity also varies—IV unlimited, IM up to 3-5 mL, subcutaneous typically 1 mL or less. Match route to urgency and drug characteristics.


Topical and Transdermal Routes: Through the Skin

These routes deliver medication to or through the skin. The key distinction is intent: topical aims for local effects at the application site, while transdermal delivers systemic effects through controlled absorption.

Topical Application

  • Applied directly to skin or mucous membranes for localized therapeutic effects
  • Minimal systemic absorption—includes creams, ointments, gels, and lotions for conditions like dermatitis or localized pain
  • Assess skin integrity before application; wear gloves to prevent nurse absorption of medication

Transdermal Patches

  • Delivers medication systemically through intact skin via adhesive patch with controlled-release technology
  • Steady drug levels over extended periods (hours to days)—improves compliance for chronic conditions
  • Common uses: fentanyl for pain, nitroglycerin for angina, nicotine for smoking cessation, estrogen for hormone replacement

Compare: Topical vs. Transdermal—both go on the skin, but the therapeutic goal differs entirely. Topical treats the local area (think hydrocortisone cream for a rash), while transdermal delivers systemic medication (think fentanyl patch for chronic pain). Exam questions often test whether you understand this distinction.


Quick Reference Table

ConceptBest Examples
Fastest onset (emergency use)IV, Inhalation, Intranasal, Sublingual
Bypasses first-pass metabolismIV, IM, Subcutaneous, Sublingual, Intranasal, Transdermal
Subject to first-pass metabolismOral, Rectal (partial)
Requires sterile techniqueIV, IM, Subcutaneous
Alternative when patient can't swallowRectal, Sublingual, Intranasal, Parenteral routes
Sustained/controlled releaseTransdermal patches, Subcutaneous, IM depot
Local effects onlyTopical application
Technique-dependent effectivenessInhalation (MDIs, nebulizers)

Self-Check Questions

  1. A patient is experiencing an acute angina attack and needs immediate relief. Which two routes would provide the fastest onset, and why are they preferred over oral administration?

  2. Compare and contrast subcutaneous and intramuscular injection routes in terms of absorption rate, volume capacity, and appropriate clinical uses.

  3. A patient is vomiting and cannot take oral medications but needs systemic fever reduction. Which routes could you consider, and what factors would influence your choice?

  4. Why do sublingual and intranasal medications often have higher bioavailability than oral medications of the same drug? Explain the pharmacokinetic principle involved.

  5. An FRQ asks you to explain why transdermal fentanyl patches are appropriate for chronic pain but not for acute pain management. What key characteristics of this route support your answer?