Fundamentals of Nursing: Medication Administration
Fundamentals of Nursing, 2nd Edition
Chapter 35: Medication Administration
Key Terms, Definitions & Concepts
Absorption (p. 801)
Definition: The passage of a drug from the administration site into the bloodstream.
Key factors affecting absorption:
- Route of administration
- Ability of the drug to dissolve (become soluble)
- Blood flow to the administration site
- Body surface area
- Patient ageExample: An oral tablet must dissolve in the gastrointestinal tract and pass through the intestinal wall before entering the bloodstream. IV medications bypass absorption entirely and enter circulation immediately, making IV the fastest route, followed by IM (intramuscular), subcutaneous, and then oral.
Adverse Effects (p. 803)
Definition: Severe, unintended, unwanted, and often unpredictable drug reactions.
Example: A patient develops a severe allergic skin response (beyond a mild rash) after taking an antibiotic. Unlike side effects, adverse effects are serious and may require immediate intervention or discontinuation of the medication.
Allergic Reactions (p. 803)
Definition: Unpredictable immune responses caused by antibody reactions to antigens (the medication or one of its components).
Example: A patient receiving penicillin develops a rash, itchy skin, inflammation and swelling of the nasal passages, and raised skin eruptions (urticaria/hives). Severe allergic reactions are referred to as anaphylactic reactions.
Anaphylactic Reaction (p. 803)
Definition: A severe, life-threatening allergic reaction that is a medical emergency; characterized by sudden onset of bronchiolar constriction, edema of the pharynx and larynx, shortness of breath, acute hypotension, and tachycardia.
Example: A patient receives a dose of IV penicillin and within minutes develops swelling of the tongue, difficulty breathing, and a sudden drop in blood pressure. Treatment includes immediate discontinuation of the drug, administration of epinephrine, IV fluids, steroids, antihistamines, and respiratory support.
Antagonism (p. 803)
Definition: A drug interaction in which the effect of one drug is decreased or blocked by the presence of another substance, including herbs or other medications.
Example: Antibiotics can lessen the effectiveness of birth control pills. Grapefruit juice can alter the absorption of statins, acting as an antagonist by interfering with the drug's intended effect.
Buccal (p. 807)
Definition: A route of medication administration in which the medication is placed between the cheek and the gum (against the cheek), where it is absorbed through the mucous membrane.
Example: Certain testosterone or nitroglycerin preparations are placed in the buccal pouch. The medication dissolves slowly and is absorbed directly into the bloodstream without going through the digestive system.
Controlled Substances (p. 800)
Definition: Drugs that have the potential for abuse or dependency and are regulated under the Controlled Substances Act, classified into schedules I through V based on their potential for abuse and accepted medical use.
Example: Schedule I drugs (e.g., heroin) have no approved medical use in the U.S. Schedule II drugs (e.g., morphine, methylphenidate/Ritalin) have high abuse potential and require strict prescription controls. Nurses must count controlled substances at specific times (most commonly at shift change) and keep them under double lock or in a secured computerized medication cabinet.
Distribution (p. 802)
Definition: The process of delivering a medication to tissues and organs, and ultimately to the specific site of action, after it has been absorbed into the bloodstream.
Example: After a pain medication is absorbed into the bloodstream, it is distributed throughout the body - affecting the nervous system (sedation), respiratory system (changes in respiratory rate), and gastrointestinal system (constipation). Factors affecting distribution include blood flow, plasma protein binding, and the drug's ability to cross cell membranes.
Drug (p. 803)
Definition: Any substance that positively or negatively alters physiologic function.
Example: Alcohol is a drug because it alters physiologic function (CNS depression). Caffeine is a drug because it stimulates the central nervous system. Not all drugs are medications; a drug becomes a medication when it is specifically administered for a therapeutic (beneficial) purpose.
Drug Incompatibility (p. 804)
Definition: A chemical or physical reaction that occurs when medications are mixed together in a solution, causing precipitation, or when combining a drug with another drug causes an adverse chemical reaction, rendering one or both drugs ineffective or harmful.
Example: Mixing certain IV antibiotics with other IV solutions can cause them to precipitate (form particles), making them unsafe to administer. Nurses must check compatibility before combining any medications in a single syringe or IV bag.
Excretion (p. 802)
Definition: The process by which the body eliminates a drug and its metabolites, primarily through the kidneys via urine, but also through the lungs, skin, bile, or feces.
Example: Most medications are filtered by the kidneys and excreted in the urine. A patient with chronic kidney disease may not excrete drugs efficiently, causing the drug to accumulate in the body and potentially leading to toxicity. Nurses should assess renal function (BUN, creatinine) before administering medications.
Generic Name (p. 800)
Definition: The official, non-proprietary name of a drug assigned by the U.S. Adopted Names Council; it is not capitalized and often contains a prefix or suffix that helps identify the drug class.
Example: "ibuprofen" is the generic name. It is not capitalized and is used across all manufacturers. The generic name is typically based in part on the chemical name but is shortened for practical use.
Half-Life (p. 802)
Definition: The expected time it takes for the blood concentration of a drug to decrease to one-half of the original drug dose due to drug metabolism and excretion.
Example: If a medication has a half-life of 4 hours and a patient takes a 500 mg dose, then 4 hours later only 250 mg remains active in the bloodstream. A patient with liver or kidney damage may have an extended half-life because the drug is not being eliminated efficiently, increasing the risk of drug accumulation and toxicity.
Idiosyncratic Reaction (p. 803)
Definition: An unexpected, unusual, and unpredictable drug response that may be individual to a specific patient; it is not a typical side effect or known adverse effect.
Example: A patient is given a sedative (such as zolpidem/Ambien) to help with sleep, but instead becomes wide awake and agitated. This opposite-of-expected reaction is idiosyncratic, and these reactions are not predictable based on the drug's pharmacology.
Inhalation (p. 809)
Definition: A route of medication administration in which the drug is breathed into the lungs and bronchi through the mouth or nose, allowing rapid absorption through the respiratory mucosa.
Example: A patient with asthma uses an albuterol inhaler. The medication is inhaled as a fine mist, travels to the bronchioles, and causes rapid bronchodilation. This route allows for both local (lung) and systemic effects.
Intradermal (p. 809)
Definition: A route of parenteral medication administration in which a small amount of medication is injected between the layers of the skin (into the dermis), just below the epidermis.
Example: A tuberculosis (TB) skin test (Mantoux test) is administered intradermally, typically on the inner forearm. A small bleb (bubble) forms under the skin at the injection site. This route is used for allergy testing and certain vaccinations.
Intramuscular (IM) (p. 810)
Definition: A route of parenteral medication administration in which medication is injected directly into muscle tissue, allowing for relatively rapid absorption into the bloodstream.
Example: A flu vaccine is commonly given as an IM injection into the deltoid muscle of the upper arm. IM injections are absorbed faster than subcutaneous injections because muscle tissue has a greater blood supply. Common IM sites include the deltoid, vastus lateralis, and ventrogluteal muscles.
Intravenous (IV) (p. 810)
Definition: A route of parenteral medication administration in which medication is delivered directly into a vein, providing immediate access to the bloodstream and the fastest onset of action of all administration routes.
Example: A patient in severe pain receives IV morphine. Because the medication enters the bloodstream directly, pain relief begins within minutes. The IV route is also used for large fluid volumes and continuous medication infusions (e.g., antibiotics via IV piggyback).
Medication (p. 802)
Definition: A drug that is specifically administered for its therapeutic (beneficial) effect on physiologic function.
Example: Ibuprofen (Advil) is a medication when prescribed or taken for the therapeutic purpose of reducing pain and inflammation. All medications are drugs, but not all drugs are medications; the distinction lies in the intent of therapeutic benefit.
Medication Error (p. 812)
Definition: Any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of a health care professional, patient, or consumer.
Example: A nurse administers 10 mg of a medication instead of the prescribed 5 mg due to a decimal point error. Other examples include giving medication to the wrong patient, using the wrong route, or administering at the wrong time. Prevention strategies include the use of computerized order entry and bar-code scanning systems.
Medication Interactions (p. 803)
Definition: Alterations in a drug's action that occur when the drug is taken with another medication, food, herb, or supplement, which can increase or decrease the desired effect of one or both substances.
Example: Warfarin (a blood thinner) interacts with vitamin K found in leafy green vegetables - eating large amounts of spinach can decrease warfarin's effectiveness. Grapefruit juice interacts with statins by altering their absorption. The more medications a patient takes, the greater the risk of interactions.
Metabolism (p. 802)
Definition: The biochemical process by which the body breaks down (biotransforms) a drug, primarily in the liver, to create compounds that are more easily excreted from the body.
Example: When a patient takes acetaminophen (Tylenol) orally, the liver metabolizes it into compounds that can be excreted by the kidneys. In a patient with liver disease (e.g., cirrhosis), metabolism is impaired, so the drug remains in the body longer, increasing the risk of toxicity.
NPO (p. 820)
Definition: A Latin abbreviation for “nil per os,” meaning “nothing by mouth.” A patient designated NPO is not permitted to eat, drink, or take oral medications.
Example: A patient scheduled for surgery at 8 a.m. is placed on NPO status after midnight. The nurse must hold all oral medications and notify the prescribing provider, who may order alternative routes (IV, IM, or transdermal) for essential medications such as antihypertensives or cardiac drugs.
Onset of Action (p. 802)
Definition: The time it takes for the body to respond to a drug after it has been administered; influenced by the administration route, drug formulation, and pharmacokinetic factors.
Example: An IV medication may have an onset of action within seconds to minutes, while an oral medication may take 30-60 minutes. A patient in severe pain would benefit more from an IV analgesic (fast onset) than an oral one (slower onset).
Oral (p. 807)
Definition: A route of medication administration in which the drug is taken through the mouth and swallowed, making it the most common and convenient route of administration.
Example: A patient swallows a daily aspirin tablet with a glass of water. The tablet dissolves in the stomach, is absorbed in the small intestine, and enters the bloodstream. Oral medications are contraindicated in patients who are NPO, unconscious, vomiting, or unable to swallow.
Parenteral (p. 807)
Definition: A route of medication administration in which the drug is given by injection or infusion, bypassing the gastrointestinal tract; includes intradermal, subcutaneous, intramuscular, and intravenous routes.
Example: A diabetic patient administers insulin subcutaneously (under the skin) every morning. Because insulin is destroyed by stomach acid and cannot be absorbed orally, it must be given parenterally. Other parenteral examples include IM antibiotics and IV chemotherapy.
Peak Plasma Level (p. 803)
Definition: The highest serum (blood) concentration of a drug, reached when absorption is complete and the drug is at its maximum level in the bloodstream.
Example: When monitoring a patient on gentamicin (an antibiotic), the nurse draws a "peak" blood level 30-60 minutes after IV administration to ensure the drug has reached a therapeutic concentration. If the peak level is too high, it may indicate risk for toxicity (e.g., kidney or hearing damage with gentamicin).
Pharmacodynamics (p. 801)
Definition: The process by which a medication interacts with the body's cells to produce a biological response; the study of what the drug does to the body.
Example: Morphine binds to opioid receptors in the central nervous system, producing pain relief (analgesia), sedation, and slowed respiratory rate. The biochemical response can be systemic - a single drug affecting multiple body systems simultaneously.
Pharmacokinetics (p. 801)
Definition: The study of how a medication enters the body, moves through the body, and ultimately leaves the body; encompasses the four processes of absorption, distribution, metabolism, and excretion (ADME).
Example: When a patient takes an oral antibiotic: it is absorbed in the small intestine (absorption), carried through the bloodstream to the site of infection (distribution), broken down by the liver (metabolism), and finally eliminated through the kidneys in the urine (excretion). Understanding pharmacokinetics helps nurses anticipate drug actions, interactions, and appropriate dosing schedules.
Prescription (p. 805)
Definition: A written or electronic order from an authorized health care provider (physician, dentist, qualified nurse practitioner, or physician assistant) directing the preparation and administration of a medication for a specific patient.
Example: A physician writes: "Amoxicillin 500 mg PO every 8 hours for 10 days." A legally valid prescription must include the patient's name, date and time the order was written, the name of the drug, the dosage, the route of administration, the frequency, and the signature of the prescribing provider.
Side Effects (p. 803)
Definition: Predictable but unwanted and sometimes unavoidable reactions to a medication that occur even at therapeutic doses; may be minor, harmless, or harmful.
Example: A patient taking diphenhydramine (Benadryl) for allergies experiences drowsiness. This is a known, predictable side effect of the medication, not an allergic or adverse reaction. Nausea is another common side effect of many medications. Unlike adverse effects, side effects are expected and anticipated.
Six Rights of Medication Administration (p. 817)
Definition: A safety framework used by nurses to reduce medication errors, ensuring that the correct medication is given safely and appropriately every time.
The Six Rights are:
1. Right Patient - Verify patient identity using two identifiers (name and date of birth or medical record number)
2. Right Medication - Confirm the correct drug name matches the order
3. Right Dose - Verify the correct amount of medication
4. Right Route - Confirm the correct method of administration (oral, IV, IM, etc.)
5. Right Time - Administer at the correct scheduled time
6. Right Documentation - Record the medication given immediately after administrationExample: Before giving a patient their 8 a.m. medications, the nurse scans the patient's armband (right patient), checks the medication name on the MAR (right medication), confirms the dose calculation (right dose), verifies the route (right route), checks the time (right time), and documents after giving (right documentation).
Subcutaneous (p. 810)
Definition: A route of parenteral medication administration in which medication is injected into the subcutaneous tissue (the fatty layer just beneath the skin), allowing for slower, sustained absorption compared to IM injection.
Example: Insulin is commonly administered subcutaneously into the abdomen, upper arm, or thigh. A patient with diabetes uses a short needle inserted at a 45-90 degree angle to deliver insulin into the subcutaneous fat layer. Absorption is slower than IM but faster than oral.
Sublingual (p. 807)
Definition: A route of medication administration in which the drug is placed under the tongue, where it dissolves and is rapidly absorbed directly into the systemic circulation through the mucous membranes, bypassing the liver's first-pass metabolism.
Example: A patient experiencing chest pain places a nitroglycerin tablet under the tongue. The tablet dissolves quickly, and the medication enters the bloodstream within minutes, providing rapid relief of angina. The sublingual route is more potent than the oral route because the drug bypasses the digestive system and liver.
Synergistic Effect (p. 803)
Definition: A drug interaction in which the combined effect of two or more substances taken together is greater than the sum of their individual effects (1 + 1 = more than 2).
Example: Alcohol combined with a central nervous system (CNS) depressant (such as a benzodiazepine like lorazepam) produces a synergistic effect - the combined CNS depression is far greater than either substance alone, potentially causing life-threatening respiratory depression. Physicians may intentionally use synergistic effects to achieve a greater therapeutic response (e.g., combining two pain medications).
Therapeutic Effect (p. 801)
Definition: The intended, desired result or action of a medication; the reason the drug was prescribed.
Example: A patient is prescribed lisinopril (an ACE inhibitor) for hypertension. The therapeutic effect is a reduction in blood pressure to a normal range. The nurse evaluates whether the therapeutic effect has been achieved by monitoring the patient's blood pressure after administration.
Topical (p. 807)
Definition: A route of medication administration in which the drug is applied directly to the skin or mucous membranes, producing primarily a local effect at the site of application.
Example: A patient with a skin infection applies a prescription antibiotic cream (mupirocin/Bactroban) directly to the wound. Eye drops, ear drops, vaginal creams, and rectal suppositories are also considered topical medications. Transdermal patches are a specialized form of topical medication that produces systemic effects.
Toxic Effects (p. 803)
Definition: Serious physiologic effects that result from a medication overdose or the buildup of medication in the blood due to impaired metabolism and excretion; can affect any body system and may be life-threatening.
Example: A patient with kidney disease taking digoxin (a cardiac medication) develops nausea, visual disturbances, and dangerous heart rhythm changes due to the drug accumulating in the bloodstream because it cannot be adequately excreted. Toxic effects are monitored through drug serum levels (e.g., digoxin levels, lithium levels).
Trade Name (p. 800)
Definition: The registered, proprietary brand name assigned to a medication by the pharmaceutical manufacturer; it is capitalized and owned by the company that produced the drug.
Example: "Tylenol" is the trade (brand) name for the generic drug acetaminophen. "Advil" is the trade name for ibuprofen. Multiple manufacturers may produce the same generic drug under different trade names. Trade names are always capitalized, while generic names are not.
Transdermal Patch (p. 809)
Definition: A specialized topical medication delivery system in which a drug-containing adhesive patch is applied to the skin, allowing the medication to be absorbed slowly and continuously through the skin into the systemic circulation over an extended period.
Example: A patient with chronic pain wears a fentanyl transdermal patch on their upper arm, which delivers a continuous dose of the opioid pain medication over 72 hours. Other examples include nicotine patches (for smoking cessation) and nitroglycerin patches (for angina prevention). Nurses must rotate patch sites and remove old patches before applying new ones.
Trough (p. 803)
Definition: The lowest serum (blood) concentration of a medication, measured just before the next scheduled dose is given; used to monitor drug levels and ensure the medication has not dropped below therapeutic range.
Example: For a patient receiving gentamicin (an antibiotic), the nurse draws a trough blood level 30 minutes before the next dose is due. If the trough level is too high, it may indicate the drug is accumulating and not being cleared, increasing the risk of kidney or hearing damage. Trough levels are commonly monitored for aminoglycoside antibiotics and vancomycin.