Pharmacology - Drug Action, Pharmacokinetics & Pharmacodynamics Flashcards

Question 1

What is Pharmacology?

Accepted Answer

The scientific study of drugs, encompassing their origins, chemical properties, mechanisms of action, uses, and adverse effects on living systems.

Question 2

What is Bioavailability?

Accepted Answer

The fraction of an administered drug dose that reaches the systemic circulation in an unchanged form and is available to produce its pharmacological effect. It is often expressed as a percentage.

Question 3

Differentiate between Pharmacokinetics and Pharmacodynamics.

Accepted Answer

**Pharmacokinetics** describes "what the body does to the drug" (ADME processes). **Pharmacodynamics** describes "what the drug does to the body" (mechanism of action, therapeutic effects, adverse effects).

Question 4

What does the acronym ADME represent in pharmacokinetics?

Accepted Answer

ADME stands for **A**bsorption, **D**istribution, **M**etabolism, and **E**xcretion, which are the four fundamental processes governing a drug's fate in the body.

Question 5

Define Drug Absorption.

Accepted Answer

The process by which an unchanged drug moves from its site of administration into the systemic circulation (bloodstream).

Question 6

List key factors influencing drug absorption.

Accepted Answer

Factors include drug solubility (lipid vs. water), concentration at the absorption site, route of administration, blood flow to the absorption site, surface area of absorption, and drug formulation.

Question 7

Explain the First-Pass Effect (or Pre-systemic Metabolism).

Accepted Answer

The phenomenon where a drug is extensively metabolized in the liver or gut wall before reaching systemic circulation, significantly reducing its bioavailability, especially after oral administration.

Question 8

Define Drug Distribution.

Accepted Answer

The reversible transfer of a drug from the systemic circulation into the interstitial and intracellular fluids of tissues.

Question 9

What factors influence drug distribution?

Accepted Answer

Factors include blood flow to tissues, tissue permeability (e.g., blood-brain barrier), plasma protein binding, and the drug's lipid solubility and ionization state.

Question 10

What is the significance of plasma protein binding in drug distribution?

Accepted Answer

Only unbound (free) drug can cross membranes and exert pharmacological effects. High protein binding can reduce the amount of free drug available, potentially prolonging its duration of action or leading to drug interactions.

Question 11

Define Drug Metabolism (Biotransformation).

Accepted Answer

The process by which the body chemically alters drugs, primarily in the liver, to facilitate their excretion. This often converts lipid-soluble drugs into more water-soluble metabolites.

Question 12

What is the primary site of drug metabolism, and which enzyme system is crucial?

Accepted Answer

The liver is the primary site. The **Cytochrome P450 (CYP450)** enzyme system is a superfamily of enzymes responsible for the majority of drug metabolism.

Question 13

Differentiate between Phase I and Phase II metabolic reactions.

Accepted Answer

**Phase I reactions** (e.g., oxidation, reduction, hydrolysis) introduce or expose polar groups, often making the drug more reactive. **Phase II reactions** (conjugation) involve attaching endogenous polar molecules (e.g., glucuronic acid) to the drug or its Phase I metabolite, making it more water-soluble for excretion.

Question 14

Define Drug Excretion.

Accepted Answer

The irreversible removal of drugs or their metabolites from the body, primarily via the kidneys in urine, but also through bile, feces, sweat, breath, or breast milk.

Question 15

What is the primary route of drug excretion?

Accepted Answer

Renal excretion (via the kidneys into urine) is the most common and important route for the elimination of many drugs and their metabolites.

Question 16

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

Accepted Answer

The time required for the concentration of a drug in the plasma to decrease by 50%. It is a key pharmacokinetic parameter determining dosing frequency and time to reach steady state.

Question 17

How many half-lives does it typically take for a drug to reach steady-state concentration or be almost completely eliminated from the body?

Accepted Answer

Approximately **4 to 5 half-lives** are generally required for a drug to reach steady-state concentration during continuous dosing or to be considered almost completely eliminated after a single dose.

Question 18

What is a Drug-Receptor Interaction?

Accepted Answer

The binding of a drug molecule to a specific biological macromolecule (receptor), usually a protein, leading to a change in cellular function and a pharmacological effect.

Question 19

Define an Agonist in pharmacology.

Accepted Answer

A drug that binds to a receptor and activates it, producing a pharmacological response similar to that of the endogenous ligand. Agonists can be full or partial.

Question 20

Define an Antagonist in pharmacology.

Accepted Answer

A drug that binds to a receptor but does not activate it. Instead, it blocks the binding of agonists (endogenous ligands or other drugs), thereby preventing or reversing their effects.

Question 21

Differentiate between Competitive and Non-Competitive Antagonists.

Accepted Answer

**Competitive antagonists** bind reversibly to the same site as the agonist, competing for binding. Their effects can be overcome by increasing agonist concentration. **Non-competitive antagonists** bind irreversibly or to an allosteric site, reducing the maximal response of the agonist regardless of its concentration.

Question 22

What is a Dose-Response Relationship?

Accepted Answer

The relationship between the dose of a drug and the magnitude of the pharmacological effect it produces. It is often depicted graphically and helps characterize drug efficacy and potency.

Question 23

Define Efficacy in the context of drug action.

Accepted Answer

The maximal pharmacological effect (response) that a drug can produce, regardless of the dose. It reflects the drug's ability to activate a receptor and elicit a response.

Question 24

Define Potency in the context of drug action.

Accepted Answer

The amount of drug required to produce a given effect. A drug with high potency produces a significant effect at a lower dose compared to a drug with lower potency. It is often represented by $EC_{50}$ (effective concentration for 50% maximal effect).

Question 25

What is the Therapeutic Index (TI)?

Accepted Answer

A measure of drug safety, calculated as the ratio of the dose that produces toxicity in 50% of the population ($TD_{50}$) to the dose that produces a therapeutic effect in 50% of the population ($ED_{50}$). A higher TI indicates a wider margin of safety. ($TI = \frac{TD_{50}}{ED_{50}}$)

Pharmacology - Drug Action, Pharmacokinetics & Pharmacodynamics

Card Preview

Related Flashcard Sets

French A1/A2 - Core Vocabulary & Beginner Grammar

SQL Performance Tuning - Indexing, Query Optimization & Execution Plans

AWS Solutions Architect Associate (SAA-C03) - Core Services & Architecture

CHEM204 - Organic Chemistry II: Spectroscopic Analysis & Synthesis