PAT201 Pathotherapeutics I - Week 2 Pharmacology Key Concepts

Vocabulary flashcards covering core pharmacokinetic, pharmacodynamic, pharmacogenetic, and clinical concepts from PAT201 Week 2 lecture notes.

Pharmacokinetics

The study of processes that determine how much drug reaches the target site and for how long.

Pharmacodynamics

The study of processes that determine what a drug does at its target site.

ADME

The four pharmacokinetic processes—absorption, distribution, metabolism, and excretion—that determine drug movement through the body and the concentration available to act.

Absorption

The pharmacokinetic process describing how a drug gets from its administration site into systemic circulation.

Bioavailability

The fraction of an administered dose that reaches systemic circulation.

First-pass metabolism

Presystemic metabolism in the liver that occurs after gastrointestinal absorption as drugs travel through portal circulation, reducing the amount of active drug available.

IV bioavailability

Intravenous drug administration that places the drug directly into systemic circulation, bypassing absorption and providing $100\%$ bioavailability.

Distribution

The pharmacokinetic process determining whether a drug reaches intended tissues and how much remains available to act once inside systemic circulation.

Unbound fraction

The free portion of a drug not bound to plasma proteins, which is available to leave circulation and reach targets.

Metabolism

The process that changes drug structure, often making it more water-soluble and easier to eliminate.

Excretion

The process that removes drugs or metabolites from the body, helping determine drug concentration and duration of effect.

Enterohepatic recirculation

A process where drug-related substances enter bile, reach the intestine, and are reabsorbed into circulation, delaying elimination.

Minimum effective concentration

The drug concentration threshold below which the drug may not produce its intended effect.

Toxic concentration

The drug concentration level where excessive exposure increases the risk of harmful effects.

Therapeutic range

The concentration interval used to balance drug effectiveness and toxicity.

Half-life

The time required for drug concentration to decrease by $50\%$, which helps estimate drug accumulation and elimination.

Loading dose

A larger initial dose administered to achieve a target drug concentration more quickly.

Maintenance doses

Repeated doses administered to replace eliminated drug and maintain therapeutic concentrations.

Steady state

A stable concentration pattern generally approached after approximately $4$ to $5$ half-lives when dosing and clearance remain stable.

Agonist

A drug that activates a receptor and produces a biological response.

Partial agonist

A drug with lower maximal activity than a full agonist that can reduce a full agonist's effect when competing at the same receptor.

Antagonist

A drug that blocks receptor activation by an agonist rather than producing the agonist response.

Therapeutic index

A ratio comparing harmful or lethal doses to effective doses, describing a drug's margin of safety.

Additive effect

A drug combination effect that equals the exact sum of the individual drug effects.

Synergistic effect

A drug combination effect that is greater than the expected sum of the individual drug effects.

Pharmacogenetics

The study of how inherited genetic differences affect a person's response to drugs.

Contraindication

A patient condition or circumstance in which a drug should not be used.

Interaction

An occurrence where another drug, food, or natural health product changes a drug's action or exposure.

Indication

The clinically defined reason why a drug is used.

Mechanism of action

The specific process through which a drug produces its effect.

Desired effect

The intended beneficial response produced by a drug.

Adverse effect

An unwanted or harmful response produced by a drug.

Morphine

An opioid receptor agonist indicated for severe pain and breathlessness that produces analgesia, with potential adverse effects including sedation, constipation, dizziness, orthostatic hypotension, and respiratory depression.

Naloxone

A competitive opioid receptor antagonist indicated for suspected opioid toxicity and respiratory depression, having a half-life of approximately $1.5\,\text{hours}$.