Pharmacokinetics

Question 1

Four components of pharmacokinetics

Answer 1

ADME

Absorption

Distribution

Metabolism

Excretion

Question 2

Distribution

Answer 2

Question 3

Parenteral

Answer 3

Avoiding the epithelial barrier

Question 4

Bioavailability

Answer 4

Question 5

Absorption pH dependency

Answer 5

Question 6

Weak acids are better absorbed in the ____. Weak bases are better absorbed in the ____.

Answer 6

Weak acids are better absorbed in the stomach. Weak bases are better absorbed in the duodenum.

Question 7

Common drug barriers

Answer 7

Question 8

Effects of chemical affinity on biodistribution

Answer 8

Question 9

Drug halflife

Answer 9

Question 10

Volume of distribution

Answer 10

Question 11

Vd is calculated by ____.

Answer 11

Vd is calculated by dividing the administered dose by the plasma concentration at time zero

Question 12

Calculating a loading dose

Answer 12

C₀ x V_D

Question 13

Clearance

Answer 13

Where elimination is the sum of metabolic and excretory elemination.

Question 14

Calculating dose/time

Answer 14

Clearance x Target concentration

Question 15

phase I and phase II hepatic metabolism

Answer 15

Question 16

Excretion by kidney

Answer 16

Question 17

Glomerular filtration

Answer 17

Drugs enter the kidney through renal arteries, which divide to form a glomerulus. Free drug (not bound to albumin) flows through the capillary slits into Bowman’s space as part of the glomerular filtrate. Since polar molecules are less likely to be bound to albumin, they are more likely to be filtered, which will help them to be excreted in the urine.

Question 18

Proximal tubular secretion

Answer 18

Drugs that were not transferred into the glomerular filtrate leave the glomeruli through efferent arterioles, which divide to form a capillary plexus surrounding the nephric lumen in the proximal tubule. Drugs may then be actively secreted back into the glomerular filtrate in the proximal tubule. There are pumps that can move highly charged molecules (the result of phase 2 metabolism) into the proximal tubule.

Question 19

Distal tubular reabsorption

Answer 19

As a drug moves toward the distal convoluted tubule, its concentration increases and exceeds that of the perivascular space. The drug, if uncharged, may diffuse out of the nephric lumen, back into the systemic circulation. In contrast, charged metabolites will remain in the urine, again indicating the importance of phase 2 drug metabolism that makes molecules more polar.

Question 20

First vs Second Order Elimination Kinetics

Answer 20

Question 21

Elimination Kinetics Equations

Answer 21

Question 22

Zero-order kinetics occurs when ___. First-order kinetics occurs when ___.

Answer 22

Zero-order kinetics occurs when the enzyme is saturated with substrate and is working at V_max. First-order kinetics occurs when the enzyme is not satuated and reaction rate falls as substrate concentration falls.

Question 23

Clearance can best be defined as. . .

Answer 23

The volume of plasma that is cleared of drug per unit time