Nurses don't prescribe or fill prescriptions, but understanding what happens to a medication after administration drives correct assessments, client education, and evaluation of effectiveness.

Pharmacokinetics (PK) — "the body acting on the drug"

Who Decides What a Medication Can Be Sold As

The Center for Drug Evaluation and Research (CDER), part of the FDA, polices prescription & OTC medications (incl. generics, biologics, sunscreens, antiperspirants, dandruff shampoo, fluoride toothpaste). Manufacturers must submit testing evidence; CDER licenses a medication only if benefits outweigh known risks.

What Makes Up a Pharmacological Class

A pharmacological class = a group of agents sharing any combination of these 3 attributes. Development order: identify mechanism (transport/digestion/expulsion/absorption) → dosage/route → side/adverse effects & contraindications → population impact & interactions → compare efficacy to similar medications.

Quick Reference — Common Prescription Abbreviations

Absorption = moving a medication into systemic circulation. Gastric routes absorb the smallest amount — this is why oral doses of the same drug are often higher than IV doses.

Three Ways Medications Cross Membranes

Route-by-Route Absorption Outcomes

Think of the circulatory system as the train track and plasma as the train carrying medication to its site of action. Goal: achieve a therapeutic concentration at the site of action.

Protein Binding

• Medications bind to plasma proteins (mainly albumin) or stay free — only free medication can act at receptor sites.
• High protein-binding affinity → slow, sustained release, longer half-life, less toxicity while bound.
• Malnutrition/hypoproteinemia → less albumin available → more free (active) drug → ↑ toxicity risk.
• Displacement risk: a 2nd medication with higher binding affinity can knock a 1st medication off albumin — dangerous if the displaced drug has a narrow therapeutic index.

Blood-Brain Barrier (BBB) — What's Behind the Checkpoint

Two Other Barriers Worth Knowing

Tissue Permeability: Kidney & liver membranes are easily permeated; CNS tissue is not. Medications that can't permeate readily need transporter assistance.

Metabolism (biotransformation) chemically alters a medication so it can be excreted — mainly in the liver, but also kidneys, GI tract, skin, plasma, lungs.

The 3 Phases of Metabolism

What Alters the Rate of Metabolism

CYP450 — Induction vs. Inhibition

Clinical relevance: meds with a high first-pass effect + liver disease → watch for decompensation signs (jaundice, confusion, ascites, edema, spontaneous bleeding) and hold meds if present. Lipid-lowering drugs metabolized by the liver can cause rhabdomyolysis in hepatic decompensation.

Excretion = the final PK step — removing the medication/metabolites from the body. Primarily renal (glomerular filtration, tubular secretion/reabsorption); also lungs, skin, GI tract.

Two Excretion Pathways

GFR — The Best Indicator of Clearance

↑ GFR → ↑ filtration/excretion. ↓ GFR → ↓ excretion → toxicity risk. Monitor urine output (min. 30 mL/hr), serum creatinine, and creatinine clearance.

pH of Urine — Opposing Effect

Therapeutic effect (desired effect) = the client experiences the intended result once PK is complete. Insulin → lowered glucose, confirmed by fingerstick + s/s of hyper/hypoglycemia.

Common Lab Tests Tied to Specific Medications

Half-Life (t½) — % of Drug Remaining

Time for plasma concentration to drop by 50% — driven by clearance (renal/hepatic function).

4–8 hr short half-life — leaves the body fast, MEC can dip between doses. >24 hr long half-life — dosed less often, but higher accumulation/toxicity risk.

Peak, Trough & Random Levels

Gentamicin example: narrow range 5–10 mcg/mL; >12 mcg/mL risks ototoxicity/nephrotoxicity.

Therapeutic Range vs. Therapeutic Index

Receptors bind ligands (neurotransmitters, hormones, medications). The reaction can increase or decrease cell function — the effect depends on binding length & strength.

The 3 Receptor Actions — Lock & Key

3 Types of Antagonism

Factors Influencing Receptor Interactions

A medication interacting with its particular receptor sites to achieve an intended effect is called selective medication action.

Drug Tolerance — Needing More for the Same Effect

Prevention: start at the lowest effective dose; for opioids, add non-opioid analgesics + nonpharm pain strategies.

Withdrawal

• Abrupt removal of a tolerated substance → physical response as the body seeks homeostasis.
• Severity/timing depends on length of exposure, amount, and the drug's half-life.
• Common culprits: opioids, benzodiazepines, SSRIs, glucocorticoids.
• Clonidine (alpha-2 blocker) stopped abruptly → hypertensive crisis (life-threatening).
• Tapering + a sedation vacation reduce withdrawal risk in critical care.

Drug-Drug Interactions — PK vs. PD Impact

Medication Classification Example — Lisinopril

Pharmacological classification ties to mechanism of action; therapeutic classification ties to what condition it's used to treat. Evidence of an ineffective ACE inhibitor: BP stays the same or rises.

3 Levels of "Site of Action" — Zooming In

Other antihypertensive pharmacological classes that share the same therapeutic effect but different mechanisms: ACE inhibitors, ARBs, calcium channel blockers, beta-blockers — all grouped therapeutically under "antihypertensives," but each its own pharmacological class.

Indications for Use & Line of Therapy

An indication is a signal, manifestation, or condition that prompts a recommendation for therapy. One medication can carry several: furosemide is classified as a diuretic to treat a hypertension diagnosis, but is also indicated to help the body shed fluid/edema from heart failure.

Off-Label Use

Prescribing a medication for a purpose, dose, frequency, route, or population not on the FDA-approved label. The FDA approves the medication itself, not how providers choose to use it — off-label prescribing is legal as long as it's backed by sound evidence and documented.

Side Effect → Adverse Effect → Anaphylaxis

Antibiotics are the most common class for adverse effects — mostly immune hypersensitivity reactions. A reaction is "significant"/reportable if it causes death, a life-threatening state, hospitalization, permanent impairment, or birth defects.

Common Side Effects (across ages/medications)

Some side effects are serious despite being "expected" (major bleeding, kidney/liver damage). Mitigation: change medications, adjust dose, or take with food to ↓ GI effects.

Risks to the Client — Worked Examples

Anaphylaxis — The Deadliest Adverse Effect

• Onset: minutes to hours after administration
• Manifestations: hives, pruritus, lip/tongue/uvula swelling, ↓ BP, airway narrowing → possible respiratory failure
• ↑ death risk with COPD, asthma, coronary artery disease
• ~10% of all ADRs are immune-related — mild up to severe (angioedema, Stevens-Johnson syndrome, anaphylaxis, cardiovascular collapse)

Nursing Response Sequence

High-Alert Medications (HAMs)

Boxed Warnings

• The FDA's highest safety warning — over 400 medications currently carry one
• Usually applies to a whole medication cohort/class, not a single drug
• Meant to notify of serious risk — not an automatic contraindication
• Metoprolol: boxed warning against abrupt cessation → rebound sympathetic activation → ↑ BP/HR/cardiac event risk
• ACE inhibitors: pregnancy is an absolute contraindication

Three Words for "Meds Affecting Each Other"

DDI Categories — Pharmacodynamic vs. Pharmacokinetic

Common Drug-Food Interactions

Food can help bioavailability too — bile salts improve solubilization of poorly water-soluble drugs. Strategies: avoid the trigger food, time meds around meals, keep intake consistent (vitamin K + warfarin), or reduce amount consumed. Formulation fixes include enteric-coated, delayed-release, and modified-release products.

Drug-Condition Interactions (DDSIs)

DDSIs are unidirectional — disease affects the drug's action, not the reverse. Most common in older adults (multiple comorbidities). Product labels don't always cover every possible condition.

Anatomy of a Medication Prescription

Four Types of Prescriptions

Common Order Abbreviations

12-Hour ↔ 24-Hour (Military) Time

Military time uses 4 digits, no colon, no a.m./p.m. — it eliminates the "is that 5 a.m. or 5 p.m.?" ambiguity. Runs from 0001 (1 min after midnight) to 2400 (midnight).

Three Systems, One Bridge

Metric Prefix Ladder

Standard Conversion Factors — Memorize These

Enteral — Oral / Sublingual / Buccal

Topical & Transdermal

Mucous Membrane Instillation

Inhalation

Both: rinse mouth/brush teeth after a corticosteroid inhaler (↓ oral fungal infection risk).

MDI With a Spacer — Step Sequence

Enteral Tube (NG / Gastrostomy)

Parenteral

IM Site Selection — Safe Volume by Site

Same Problem, Three Roads — Phenytoin 0.2 g PO q8h · Available: 100 mg/capsule

Rounding by Device in Hand

Worked Examples — Solid, Liquid, Injectable & Weight-Based

Body Surface Area (BSA) — Two Formulas

Quick-Answer Drill Grid

Weight-Based Heparin — Convert Weight First, Round Last

Quick-Answer Drill Grid

Access Type & Catheter Gauge

Four Complications to Catch Early

4 Sources of Medication Errors

History → Technology — How the System Learned to Catch Errors

"Do Not Use" Abbreviations

Near Miss vs. Sentinel Event — Same Slip, Different Path

The Swiss Cheese Model — Organizational Version (Reason)

A different lens than a single practice slip: 4 organizational layers, each a slice of cheese with its own holes. Example — a heparin adverse drug event:

Why Errors Go Unreported — & What Fixes It

Clinical judgment is the process of using critical thinking and decision-making to assess, plan, and provide appropriate care. It blends knowledge, experience, intuition, and client-specific factors — letting nurses adapt care to each client rather than applying one script to everyone. It's built from the same bones as the nursing process, but is explicitly framed as an ongoing, circular cycle, not a line with an end.

The Six-Step Cycle — Richard's Asthma Exacerbation

A client's stage of life significantly changes how medications are absorbed, distributed, metabolized, and excreted. Understanding age-related PK/PD changes lets nurses recognize the need for an individualized regimen — proper dosage adjustments and monitoring based on these factors minimize the risk of adverse drug reactions.

Pediatric, Older Adult & Pregnancy/Lactation

Applying Clinical Judgment — Formulations

• Recognize Cues: collaborate with client/provider to spot data suggesting an alternate formulation is needed
• Analyze Cues: determine the client's ability to take the medication as prescribed (e.g., swallowing difficulty)
• Prioritize Hypotheses: select the formulation matching the client's specific needs
• Generate Solutions → Take Action → Evaluate Outcomes: build the medication plan, implement/teach it, then monitor for effectiveness and tolerance

Polypharmacy is the concurrent use of multiple medications — often defined as 5 or more. It's common in older adults with several chronic conditions, and it can even be intentional (a laxative prescribed to offset an opioid's constipating side effect). Other drivers: multiple prescribers, multiple diagnoses. Risks: adverse effects, drug-drug interactions, nonadherence, and higher healthcare costs. The nurse's role — regularly reassess the med list for appropriateness, educate the client, watch for ADRs, and evaluate regimen effectiveness.

Management Strategies

• Frequent medication reconciliation — update & verify the list at every transition of care
• Providers evaluate the need for each medication and consider deprescribing (tapering/discontinuing unnecessary meds)
• Layer in nonpharmacological interventions (lifestyle modification) alongside medications where possible
• Simplify regimens — pill organizers/boxes help clients navigate numerous medications and stay adherent

Beers Criteria vs. KIDs List

Pregnancy and lactation require careful consideration of medication safety for both the client and the fetus/infant — use varies widely based on the client's health conditions. The FDA built a labeling system to help providers and clients make informed decisions.

Two Kinds of Incompatibility

Both types alter a medication from its original form. Effects range from mild (↓ efficacy) to severe adverse drug events — pulmonary embolus, shock, organ failure. Drug interaction tools, medication guides, package inserts, and nursing expertise all help catch incompatibilities before they happen.

Drug-Drug Interactions — Two Mechanisms

Identify interactions using the Drug Interaction Database, EHR built-in interaction alerts, or by consulting the pharmacist. Effects on the client can include ↑ ADR risk (synergistic/antagonistic/additive), toxic elevated levels, ↓ effectiveness (worsening or prolonging illness), and generally more complicated treatment adherence.

Match the Statement to the Interaction Type

The Engage video "Clinical Judgment and SBAR: Addressing Medication Adverse Reactions" reinforces that the SBAR framework is the standard way to hand off a suspected drug-drug interaction or ADR to the provider.

Medication reconciliation is a systematic safety process comparing a client's current medication list against new prescriptions, hospital orders, or discharge instructions — catching omissions, duplications, and dosing errors. Its purpose is fundamentally to identify duplicate medications (not to discourage OTC use, save the nurse time, or cut costs). It should happen during every transition of care — between medical settings (including home health), when providers change, and at individual office visits.

Building the Reconciled List

The Four Steps

Applying Clinical Judgment — Newly Prescribed Medications

• Recognize Cues: collect client + record data; update the record with newly prescribed medications
• Analyze Cues: check the full list for duplicates/omissions; compare current vs. newly prescribed meds
• Prioritize Hypotheses: identify potential interactions between new and current medications
• Generate Solutions → Take Action → Evaluate Outcomes: plan client education, implement teaching (ADRs to report, administration method), then follow up on efficacy

A Medication's Dossier — Built From Jo's Case

Applying Clinical Judgment — Administration

• Recognize Cues: client identifiers, allergy/history review, compare medication to the prescription, needed assessments
• Analyze Cues: determine whether a contraindication exists (allergy, anomalous finding)
• Prioritize Hypotheses: if administration is indicated, prioritize monitoring, follow-up assessment & teaching needs
• Generate Solutions → Take Action → Evaluate Outcomes: plan administration + supplies + education, administer & teach, then evaluate response and understanding

The 10 Rights — Quick Recap

• Right Client — two identifiers, every time.
• Right Medication — confirm the label matches the order/prescription.
• Right Dose — verify against a safe-range reference; double-check high-alert meds.
• Right Time — within 30 minutes of the scheduled time.
• Right Route — matches the prescription; appropriate for the client's condition.
• Right Documentation — record immediately after giving, never before.
• Right Education — clear, concise teaching reinforced with teach-back/return demonstration.
• Right to Refuse — respect it, document it, notify the prescriber.
• Right Assessment — e.g., assess pain level with a pain scale before an opioid.
• Right Evaluation — did the client get the intended therapeutic effect, without an undesired response?

Routes — Quick Map by Category

Full nursing steps, positioning & angles for every route → Reading 3.

Before / During / After

Indications of a therapeutic effect vary by medication — reduced/resolved manifestations, increased functionality, stabilization, or prevention. Nurses assess this via vitals, labs, and client-reported change, then document and communicate findings, while also evaluating adherence to the regimen.

Adverse effects can stem from client factors, drug-drug interactions, medication errors, or incorrect dosing. Nursing responsibilities: ongoing assessment before/during/after administration; client education on what to report; prompt, accurate documentation (informs the whole care team and tracks safety); reporting significant ADRs through appropriate channels/safety databases; and regular follow-up reassessment.

Applying Clinical Judgment — Monitoring Effects

• Recognize Cues: monitor the client during/after administration, including vitals and physical condition
• Analyze Cues: determine whether findings indicate an adverse reaction
• Prioritize Hypotheses: rank findings by relative risk to decide which intervention comes first
• Generate Solutions: for an ADR, plan interventions in priority order — stop the medication, notify the provider, give reversal agents if applicable
• Take Action → Evaluate Outcomes: implement interventions in order, document once stable, report serious events, then evaluate the client's response

Medication administration is a major nursing responsibility — a high-frequency skill reported to make up up to 40% of the nurse's workload. Oral medications are the most commonly prescribed type; buccal and sublingual forms are not swallowed — they absorb directly through the oral mucosa into systemic circulation, fast. An enteral feeding tube (EFT) — a surgically placed gastric tube or a nasogastric tube — is used when a client can't absorb nutrition/medications normally through the GI tract or can't take them by mouth; the nurse must verify medication compatibility with the EFT and confirm tube placement before giving anything through it. An RN can delegate either skill to another RN or a competency-verified LPN, per facility policy and the state Nurse Practice Act — never to assistive personnel, and the delegating nurse remains responsible for the outcome.

Oral vs. Enteral Tube

Documentation & Equipment