Pharmacology Lecture Notes: Introduction, Pharmacokinetics, and Pharmacodynamics

Comprehensive practice flashcards defining foundational concepts, legal classifications, pharmacokinetics, and pharmacodynamics from introductory pharmacology lectures.

Drug

Any chemical substance that brings about a change in the body and is defined or recognized as such by the federal government, specifically the Food and Drug Administration (FDA).

Generic Name

The official, single universal name assigned to a drug (such as acetaminophen or midazolam); it is considered safer than brand names because each drug has only one generic name and it is the primary nomenclature tested on licensing exams.

Brand Name

The proprietary commercial trade name chosen by a drug manufacturer (such as Tylenol for acetaminophen or Versed for midazolam); a single drug can have multiple brand names depending on the manufacturer.

United States Pharmacopeia (USP)

A comprehensive national reference book (encyclopedia) listing all FDA-approved medications, formulations, dosages, and permissible excipients.

Excipients

Inactive chemical additives (such as binding agents or silica dioxide) combined with active drug powders to form stable, intact dosage forms like tablets.

Over-the-Counter (OTC) Drugs

Medications that do not require a prescription; having OTC status does not guarantee safety, as patients can easily overdose or experience toxicity if labels are not read carefully.

Controlled Substances

Prescription medications with high potential for abuse, misuse, or dependence that require strict legal safety and handling procedures (such as witnessing and documenting medication wasting in the electronic medical record).

Schedule I Controlled Substances

Drugs categorized by the federal government as having the highest abuse potential and no accepted medical use, precluding them from routine prescription (e.g., heroin and federally regulated marijuana).

Schedule II Controlled Substances

Medications with high potential for abuse but recognized medical utility that can be prescribed under strict guidelines (e.g., cocaine, methadone, hydromorphone, meperidine, oxycodone, and fentanyl).

Acetaminophen (APAP)

An analgesic and antipyretic drug that can cause severe liver damage in excessive doses; the maximum recommended aggregate dose for an average healthy adult is $4\,\text{g}$ ($4{,}000\,\text{mg}$) in a $24\text{-hour}$ period.

Aspirin (ASA)

A nonsteroidal anti-inflammatory drug (NSAID) and analgesic that can cause kidney damage and gastrointestinal ulceration/bleeding when taken in excess.

Therapeutic Class

A drug classification based on the clinical benefit or function the medication produces for the patient (e.g., antihypertensive, antipyretic, analgesic, antiemetic).

Pharmacologic Class

A drug classification based on the specific physiological mechanism of action or chemical structure (e.g., NSAID, opioid, dopamine antagonist); drugs in the same class share similar effects, mechanisms, and adverse reactions.

Indication

The clinical reason or underlying medical condition for which a physician prescribes and a patient receives a medication.

Contraindication

A specific clinical condition or circumstance indicating that a medication must be withheld because administration would cause harm (e.g., respiratory rate of $6$ breaths per minute for morphine).

Reye's Syndrome

A severe, potentially fatal condition involving brain damage that develops when aspirin is administered to young children presenting with fever or a viral illness.

Prophylactic Use

The administration of a drug to prevent a medical complication or symptom before it actually occurs (e.g., prescribing docusate sodium concurrently with opioids to avert constipation).

Off-Label Use

The clinical practice wherein a licensed prescriber uses an FDA-approved drug to treat a disease, population, or condition for which the medication was not formally tested or approved.

Drug Interaction

An alteration in the normal pharmacological activity or absorption of a drug caused by concurrent administration with another chemical, drug, or food (e.g., calcium binding tetracycline and blocking absorption).

1 C and 4 Gs Supplements

Common dietary herbal supplements (cinnamon, garlic, Ginkgo biloba, ginger, ginseng) that are not FDA-regulated and can substantially increase bleeding risk.

Pharmacokinetics

The study of how a drug enters, travels through, and exits the body, encompassing four distinct phases: absorption, metabolism, distribution, and excretion.

Absorption

The pharmacokinetic movement of a drug from its site of administration across biological membranes into the bloodstream; for oral medications, the major organ of absorption is the gastrointestinal tract.

Do-Not-Crush Drug Formulations

Medication formulations designed for gradual release that must never be crushed—indicated by abbreviations such as CR (controlled release), ER/EX/XR/XT/XL (extended release), and SR (sustained release).

Enteric-Coated (EC) Tablet

A tablet with a barrier coating that prevents dissolution and absorption in the acidic stomach so it dissolves in the small intestine; crushing an EC tablet constitutes a medication error.

Transdermal Route

Medication delivery through a skin patch that allows slow, steady, continuous absorption to maintain stable blood drug levels; contraindicated on broken skin, excessively hairy sites, paper-thin skin, or in patients with poor peripheral circulation.

First-Pass Effect

The initial hepatic metabolism of an orally absorbed drug arriving via the portal circulation, which deactivates a significant portion of the dose before it reaches systemic circulation.

Bioavailability

The percentage of an administered drug dose that successfully reaches the systemic circulation intact; intravenous (IV) push and intramuscular (IM) medications exhibit $100\%$ bioavailability.

Distribution

The pharmacokinetic transport of a drug throughout the body via the cardiovascular system to its target tissues and cells once it enters the systemic circulation.

Blood-Brain Barrier (BBB)

A protective cellular lining within brain capillaries that prevents many circulating chemicals and medications from passing into the central nervous system.

Teratogen

A chemical or pharmacological agent capable of crossing the placenta to cause physical or functional birth defects in a developing fetus.

Protein Binding

The reversible attachment of drug molecules to circulating plasma proteins (such as albumin); the bound fraction of the drug is pharmacologically inert and unavailable to body tissues.

Excretion

The pharmacokinetic elimination of drug metabolites or parent compounds from the body, primarily performed by the kidneys through urine filtration.

Start Low and Go Slow

A clinical dosing rule of thumb used for geriatric patients, initiating medications at approximately half ($50\%$) the standard adult dose and titrating upward gradually due to reduced organ clearance.

Half-Life ($t_{1/2}$)

The duration of time required for the circulating concentration of a drug currently in the body to be reduced by half ($50\%$) via excretion and elimination.

Pharmacodynamics

The study of how a drug exerts biochemical and physiological effects within the body and the mechanisms by which those actions occur.

Minimum Effective Concentration (MEC)

The lowest plasma drug concentration required to produce a discernible therapeutic response; blood levels below the MEC yield no therapeutic effect.

Onset of Action

The time elapsed from drug administration until the plasma concentration crosses the MEC to initiate a therapeutic response.

Peak Concentration

The maximum plasma drug level achieved in the bloodstream following complete absorption.

Trough Concentration

The lowest drug concentration in the bloodstream, measured immediately prior to administering the next scheduled dose.

Therapeutic Range (Therapeutic Index)

The plasma concentration interval between the MEC and the toxic level; drugs with a narrow therapeutic range have a slim safety margin and require frequent serum monitoring.

Peak and Trough Monitoring Timing

Diagnostic blood sampling performed to verify safe dosing; trough levels are drawn within the $30\text{-minute}$ window before the next dose, and peak levels are drawn within the $30\text{-minute}$ window after an infusion finishes.

Loading Dose

An initial larger-than-normal drug dose administered to rapidly raise plasma concentrations above the MEC into the therapeutic range.

Maintenance Dose

Smaller, consistent doses administered at regular intervals to maintain drug concentration within the therapeutic window after target levels are achieved.

Tachyphylaxis

A rapid, acute decrease in drug responsiveness occurring over hours to days after administration, requiring drug-free intervals (such as removing a nitroglycerin patch for $8$ to $12\,\text{hours}$ overnight).

Tolerance

A gradual reduction in drug responsiveness developing over months to years of continued use, necessitating progressively higher doses to achieve the same initial effect.

Additive Effect

A combined drug action occurring when two medications are given together and produce a total response equal to the sum of their individual actions ($2 + 2 = 4$).

Synergistic Effect

A combined drug response occurring when two medications act together to produce an effect dramatically greater than the sum of their separate actions ($2 + 2 = 7$, e.g., alcohol combined with lorazepam).

Receptor Agonist

A chemical or medication that binds to and activates a specific receptor, stimulating the characteristic cellular response associated with that receptor.

Receptor Antagonist (Blocker)

A drug that binds to a receptor without activating it, physically preventing endogenous ligands or agonist drugs from stimulating the site.

Adrenergic Receptors

Receptors associated with the sympathetic fight-or-flight response; agonist stimulation induces tachycardia, hypertension, bronchodilation, tachypnea, pupillary dilation, and reduced GI motility.

Mydriasis

Pupillary dilation triggered by adrenergic agonist stimulation of the sympathetic nervous system.

Cholinergic Receptors

Receptors (also termed muscarinic or acetylcholine receptors) associated with the parasympathetic rest-and-digest response; agonist stimulation increases bodily secretions and decreases cardiopulmonary activity.

SLUDGE and the Killer B's

A clinical mnemonic for cholinergic agonist effects: Salivation, Lacrimation, Urination, Diarrhea, GI upset/motility, Emesis, accompanied by Bradycardia, Bronchoconstriction, and Bronchorrhea.

Miosis

Pupillary constriction caused by cholinergic receptor stimulation.

Anticholinergic Drugs

Medications that block cholinergic receptors, resulting in inhibition of secretions (producing dry mouth, dry eyes, and reduced sweating) and preventing bradycardia and bronchoconstriction.

Efficacy

The magnitude of maximal therapeutic response that a drug can achieve, reflecting how well the medication works regardless of dose.

Potency

The concentration or dosage amount of a drug required to produce a given magnitude of biological effect.

Naloxone

The specific reversal agent (antidote) administered to reverse life-threatening respiratory depression caused by an opioid overdose.

Flumazenil

The specific reversal agent (antidote) administered to treat central nervous system and respiratory depression resulting from benzodiazepine toxicity.

Vitamin K

The specific antidote administered to counteract excessive anticoagulation and bleeding caused by warfarin toxicity by promoting clotting factor synthesis.