Pharmacokinetics, Pharmacodynamics, and Pharmacogenomics Flashcards

Flashcards covering key concepts from the introductory lecture on pharmacokinetics, pharmacodynamics, and pharmacogenomics, focusing on ADME processes, drug distribution, metabolism, elimination, and rates/orders of reactions.

What does ADME stand for?

Absorption, Distribution, Metabolism, and Elimination

What is pharmacokinetics?

The study of drug disposition or drug behavior over time, often involving concentration-time relationships.

Following oral administration, what must a drug do to reach its target site?

Dissolve and enter the blood to move to tissues including the effect compartment.

In pharmacokinetics, what does absorption specifically refer to?

How the drug penetrates into the blood.

Where does metabolism primarily occur, and why is it a form of elimination?

Primarily in the liver, conversion of the drug to a different chemical form, a form of elimination.

What is excretion, and what is the primary organ involved?

Elimination via primarily the kidneys.

What happens to a drug in the stomach after oral administration?

Breakdown of the drug, disintegration, and going into solution in an acidic environment.

What is first-pass metabolism?

When the drug moves from the gastrointestinal tract to the liver.

How does the IV route of drug administration differ from the oral route?

The drug is going directly into the blood, bypassing obstacles, so you require a smaller dose.

What constitutes pre-systemic metabolism, also known as first-pass metabolism?

Everything before the drug reaches systemic circulation, including breakdown in the GI tract and metabolism in the liver.

Why is the concept of free drug important in pharmacokinetics?

The drug resides in an equilibrium state between bound and unbound forms; it is the free drug that can move to the target site.

What does pharmacodynamics study?

The drug effect, focusing on drug receptors, ion channels, enzymes, and the immune system.

What is pharmacogenomics and how does it relate to pharmacokinetics and pharmacodynamics?

Genetic determination of how an individual absorbs, distributes, metabolizes, and eliminates drugs, influencing drug response.

What is the pharmaceutical process primarily concerned with?

Dosage form design to ensure the drug can get into the patient and ultimately reach its target site.

What is enterohepatic recycling?

Some parent drug can recycle from the liver back into the GI tract to undergo subsequent metabolism.

What question does the pharmacodynamic process address?

The drug producing the required pharmacological effect (what the drug does to the body).

What question does the pharmacokinetic process address?

Is the drug getting to the site of action (what the body does to the drug).

What is the definition of drug absorption?

The process by which unchanged drug moves from the site of administration to the site of measurement (blood or plasma).

What is bioavailability (F)?

The fraction of drug that reaches systemic circulation following drug administration.

What two factors does bioavailability depend on?

The extent of the drug absorbed and the speed with which that happens.

What is drug distribution?

After absorption, the drug goes via systemic circulation into blood, tissue, fat, bone, etc., distributing to target and non-target sites.

What are some determinants of drug distribution?

The extent to which the drug binds to plasma proteins, drug properties (lipid solubility, size, charge), and the need for carriers.

What is the volume of distribution?

An imaginary volume used to gauge the extent with which a drug distributes, calculated as the total amount of drug in the body over the amount in blood plasma.

What are the two main phases of drug metabolism in the liver?

Phase one reactions (oxidation, reduction, hydrolysis) via cytochrome P450 enzymes and phase two reactions (conjugation reactions).

What is drug elimination?

The irreversible removal of the parent drug from the body, either through chemical conversion (metabolism) or excretion by the kidneys.

What are the different types of metabolizers?

Ultra-rapid, extensive (normal), and poor metabolizers, based on genetic variations in liver enzymes.

What is drug clearance?

The volume of fluid cleared of drug from the body per unit time (e.g., mL/min, L/hr).

What is half-life?

The time it takes for the plasma drug concentration to reduce by 50%, determining drug administration frequency.

What does pharmacodynamics primarily involve?

Drug-receptor interactions and dose-response curves.

What is pharmacogenomics?

Genetics that determine how an individual responds to a particular drug or drug class, the underlying reason for inter-individual variability.

In pharmacokinetics, what order do most drugs behave as?

Most drugs behave by this order.

Give an example of a zero order drug

Phenytoin.

Why is a first order drug very safe?

Because it prevents drug accumulation.

What is the key pharmacokinetic parameter when talking about elimination?

The elimination rate constant.