Unit 2: Pharmocokinetics & Pharmacodynamics

Question 1

Define pharmacokinetics.

Answer 1

Pharmacokinetics: study of drug movement throughout the body; describes how the body handles medications

Question 2

What is the greatest barrier of most medications?

Answer 2

The greatest barrier is crossing membranes that separate drug from its target cell.

Question 3

Define absorption.

Answer 3

Absorption: process involving the movement of a substance from its site of administration, across body membranes, to circulating fluids. Most drugs must be absorbed to produce an effect.

Question 4

Describe the permeability of the lipid bilayer.

Answer 4

The lipid bilayer is relatively impermeable to large membranes, ions, and polar molecules and permeable to small, unionized, lipid soluble molecules.

Question 5

What does degree of ionization depend on?

Answer 5

Degree of ionization depends on surrounding pH.

*Acids are absorbed in acids; bases are absorbed in bases.

Question 6

What is the purpose of enteric coated drug products?

Answer 6

For oral consumption, drug products may be enteric coated so it will be absorbed in small intestine.

Question 7

Regular uncoated?

Answer 7

Absorption in stomach.

Question 8

Buffered?

Answer 8

Contains ions that decrease gastric acidity and slow absorption of acidic drugs.

Question 9

Define distribution.

Answer 9

Distribution: involves how pharmacological agents are transported throughout the body.

Question 10

Where in the body gets the most / least blood flow?

Answer 10

Most: heart, liver, kidney, brain
Least: skin, bone, adipose tissues

Question 11

What are drug-protein complexes?

Answer 11

Drug-protein complexes are drugs that have bound reversibly to plasma proteins and are too large to cross capillary membranes.

Question 12

What is metabolism / biotransformation and what is the primary site?

Answer 12

Metabolism / biotransformation is the process of chemically converting a drug to a form that is more easily removed by the body. Most metabolism occurs in the liver.

Question 13

What are Phase I and II metabolism?

Answer 13

Phase I: hydrolysis, oxidation, and reduction in liver

Phase II: addition of side chain conjugates (to make drugs more water soluble and easily excreted by kidneys)

Question 14

What is the hepatic microsomal enzyme system for?

Answer 14

The hepatic microsomal enzyme system inactivates drugs to accelerate their excretion.

Question 15

Define prodrug.

Answer 15

A prodrug is a biologically inactive compound that can be metabolized to produce a drug.

Question 16

What is enzyme induction?

Answer 16

Enzyme induction is the drugs’ ability to increase metabolic activity in the liver.

Question 17

What are the isoenzymes responsible for the majority of drug metabolism?

Answer 17

CYP3A4: 34%
CYP2C: (subfamily) 25%
CYP2D6: 19%
CYP1A2

Question 18

What happens if CYP enzymes are induced?

Answer 18

If CYP enzymes are induced, plasma concentrations may fall below minimum effective concentration and higher doses will be needed. Barbiturates induce their own metabolism.

Question 19

Define loading and maintenance dose.

Answer 19

Loading dose: repeated doses or higher amount of drug given to quickly achieve therapeutic range.
Maintenance dose: given to keep drug in therapeutic range.

Question 20

What is steady state modelling?

Answer 20

Steady state modelling is the state where drug concentration stays approximately the same (AD=ME).

Question 21

Define pharmacodynamics.

Answer 21

Pharmacodynamics: refers to how a drug changes the body, concerned with mechanisms of drug action and the relationships between drug concentration and responses in the body.

Question 22

Define therapeutic window.

Answer 22

Therapeutic window: lies between ED50 and TD50.

Question 23

Define potency.

Answer 23

Potency: a drug that is more potent will produce a therapeutic effect at a lower dose compared to another drug of the same class.

Question 24

Define efficacy.

Answer 24

Efficacy: the magnitude of maximal response that can be produced from a particular drug (more important than potency)

Question 25

Differentiate between agonist and antagonist.

Answer 25

Agonist: produces the same type of response as an endogenous substance.
Antagonist: will occupy receptor and prevent endogenous chemicals from acting.
Agonists have affinity and efficacy; antagonists only have affinity.

Question 26

What is an inhibitor?

Answer 26

Inhibitors bind to sites on other proteins that stop activity of that protein.

Question 27

In relation to pharmacodynamics, what four things do proteins do?

Answer 27

1) receptor
2) enzymes
3) tranport
4) ion channels