Pharmacology: Key Concepts (PAT201 FALL 2025 WEEK 2)

Vocabulary flashcards covering key concepts in pharmacology, pharmacokinetics (absorption, distribution, metabolism, excretion), pharmacodynamics, and specific drug examples.

Pharmacokinetics

How the body handles medication, involving the movement of a drug through the body to reach target tissue at a sufficient concentration to produce a therapeutic effect.

Absorption

How a drug reaches circulation from its site of administration, across membranes.

Distribution

How a drug reaches target tissue after it has been absorbed or injected.

Metabolism

How a drug is altered by the body, usually making it more water soluble and excretable.

Excretion

How a drug is removed or eliminated from the body.

Bioavailability

The amount of drug absorbed into systemic circulation that is physiologically available to reach target cells and produce an effect, expressed as a percentage.

Enteral Route

A route of drug administration involving the gastrointestinal tract (e.g., oral, sublingual, rectal).

Parenteral Route

A route of drug administration that bypasses the gastrointestinal tract, typically via injection (e.g., intravenous, intramuscular, subcutaneous).

Topical Route

A route of drug administration applied to the skin or mucous membranes for local or systemic effect.

First-Pass Effect/Metabolism

The process by which an oral drug passes through the liver via portal circulation, where it is metabolized to less active forms before reaching systemic circulation.

IV Bioavailability

Intravenous drugs have 100% bioavailability because they are delivered directly to the bloodstream.

Drug Ionization

How a drug's absorption is influenced by the pH of the surrounding fluid; acids are absorbed in acids (e.g., stomach), and bases are absorbed in bases (e.g., small intestine).

Lipid-Soluble (Lipophilic) Drugs

Drugs that cross membranes more easily than hydrophilic drugs and are more completely distributed to body tissues.

Hydrophilic Drugs

Drugs that are water-soluble and cross membranes less easily than lipid-soluble drugs.

Drug-Protein Binding

The reversible binding of some drugs to plasma proteins; only unbound (free) drugs can reach target cells.

Cytochrome P450 (CYP) Enzymes

Microsomal enzymes in the liver that carry out most metabolic activities for many drugs, determining the speed at which a drug is metabolized.

Enterohepatic Recirculation

The process where lipid-soluble drugs are reabsorbed with bile, decreasing their rate of excretion.

Plasma Drug Levels

The concentration of a drug in the blood, used to monitor therapeutic response.

Minimum Effective Concentration

The plasma drug level below which therapeutic effects will not be observed.

Toxic Concentration

The plasma drug level above which adverse effects are likely to occur.

Therapeutic Range

The plasma drug concentration between the minimum effective concentration and the toxic concentration, where desired effects are produced with minimal toxicity.

Onset of Action

The time required for a drug to exert its therapeutic effect after administration.

Duration of Action

The length of time a drug's therapeutic effect lasts.

Drug Half-Life

The time it takes for the plasma concentration of a drug to be reduced by 50%, providing an estimate of its duration of action.

Loading Dose

A larger initial dose of a drug given to achieve a therapeutic range quickly.

Maintenance Dose

Repeated doses given to maintain a drug within its therapeutic range and sustain steady plasma concentrations.

Pharmacodynamics

How a drug changes the body, related to its mechanism of action, interaction with target tissue, and concentration-response relationships.

Receptor

A cellular molecule to which a drug binds to produce its effects, typically enhancing or inhibiting existing physiological processes.

Therapeutic Index (TI)

The ratio of a drug's lethal dose to its effective dose, describing its margin of safety (larger difference equals safer drug).

Contraindication

Conditions under which a drug absolutely should not be given (e.g., pregnancy, hypersensitivity).

Drug Interaction

When a substance (another drug, food, or natural health product) decreases or increases a drug's actions.

Agonist Drug

A drug that mimics or enhances the action of a receptor, producing a response that may be greater than endogenous substances.

Partial Agonist Drug

A drug that displays both agonistic and antagonistic effects, producing weaker responses than endogenous substances.

Antagonist Drug

A drug that prevents action by competing with an endogenous substance or drug agonist for a receptor site, acting as an inhibitor or blocker.

Additive Effect

When two drugs from similar therapeutic classes create a summative response, where the total effect equals the sum of each drug's individual effect (1+1=2).

Synergistic Effect

When the effect of two drugs is greater than expected from simply adding their individual responses, enhancing each other (1+1=3).

Indications

The reasons why a particular drug is used or prescribed.

Mechanism of Action

How a drug produces its physiological or biochemical effects in the body.

Desired Effects

The intended therapeutic outcomes or what is expected to happen from drug administration.

Adverse Effects

Undesirable side effects or reactions caused by a drug.

Morphine

An opioid agonist indicated for severe pain, MI pain, and cancer pain, which binds with mu and kappa receptors to produce profound analgesia and euphoria.

Naloxone

An opioid antagonist indicated for acute opioid intoxication or overdose, which competes with opioids at mu and kappa receptor sites to reverse opioid-induced respiratory depression.