Pharmacology

Question 1

What is pharmacodynamics?

Answer 1

What a drug does to the body (biological effects and mechanism of action)

Question 2

What is pharmacokinetics?

Answer 2

What the body does to a drug (absorption, distribution, metabolism and excretion of drugs and their metabolites)

Question 3

What kinds of regulatory proteins do drugs bind to?

Answer 3

Enzymes
Carrier molecules (transporters and pumps)
Ion channels
Receptors
RNA & DNA

Question 4

What is an agonist?

Answer 4

A drug that binds to a receptor to produce or enhance a cellular response

Question 5

What is an antagonist?

Answer 5

A drug that blocks the actions of an agonist

Question 6

What is affinity?

Answer 6

The strength of association between ligand and receptor

Question 7

What is efficacy?

Answer 7

The ability of an agonist to evoke a cellular resonse

Question 8

What is the relationship/shape of the graph between concentration of agonist and % response? (On a linear plot)

Answer 8

Hyperbolic

Question 9

What is EC50 or ED50?

Answer 9

The concentration of agonist that elicits a half maximal response

Question 10

What is the relationship/shape of the graph between concentration of agonist and % response? (On a semi-logarithmic plot)

Answer 10

Sigmoidal

Question 11

Why is it useful to plot concentration against response graphs on a semi-logarithmic plot?

Answer 11

To get a more accurate determination of ED50

Question 12

What are the four factors which control drug absorption?

Answer 12

Solubility
Chemical stability
Lipid to water partition coefficient (rate of diffusion increases with the lipid solubility of the drug)
Degree of ionisation

Question 13

Many drugs exist as weak acids or weak bases existing in both ionised (A-, BH+) and unionised (AH, B) forms. Which forms diffuse readily across the lipid bilayer?

Answer 13

Only unionised forms

Question 14

What is the pKa of a drug?

Answer 14

The pH at which 50% of the drug is ionised

Question 15

How can the proportion of unionised drugs be determined?

Answer 15

Henderson-Hasselbalch equation

Question 16

Where could weak acids be absorbed?

Answer 16

Stomach - pH of stomach lumen facilitates absorption

Question 17

Where are bases absorbed?

Answer 17

Small intestine

Question 18

Are weak or strong acids and bases absorbed better?

Answer 18

Weak acids and bases are absorbed better

Question 19

Where does the majority of absorption occur?

Answer 19

Small intestine 
(Even weak acids despite pH of stomach lumen being ideal for absorption)

Question 20

What is the definition of systemic availability?

Answer 20

Amount of drug in systemic circulation/amount absorbed

Question 21

What is the systemic availability of IV drugs?

Answer 21

100%

Question 22

What are the enteral routes of drug administration?

Answer 22

Oral
Sublingual
Rectal

Question 23

What are the parenteral routes of drug administration?

Answer 23

Intravenous
Intramuscular/subcutaneous
Inhalational
Topical

Question 24

Drugs administered by which routes pass through the liver?

Answer 24

Oral

Some of the drug administered in rectal route will pass through liver

Question 25

Drugs administered by which routes enter the systemic circulation?

Answer 25

``` Buccal/sublingual Transdermal/subcutaneous Intravenous Rectal Intramuscular ```

Question 26

Which kind of drugs move between fluid compartments/across membranes readily?

Answer 26

Unionised

Question 27

Are drugs able to move freely by diffusion bound to protein?

Answer 27

No

Question 28

What is the volume of distribution (Vd)?

Answer 28

The apparent volume in which a drug is dissolved | Dose/plasma concentration

Question 29

What does a Vd of <5L imply?

Answer 29

The drug is retained in the vascular compartment

Question 30

What does a Vd of <15L imply?

Answer 30

The drug is restricted to extracellular water?

Question 31

What does a Vd of >15L imply?

Answer 31

The drug has been distributed throughout total body water e.g. highly lipid soluble drugs like ethanol

Question 32

What kind of drugs will not cross the phospholipid bilayer?

Answer 32

Polar

Question 33

What is the equation for initial concentration (Co)?

Answer 33

D/Vd (Dose, D Volume of distribution, Vd)

Question 34

What is first order kinetics?

Answer 34

Where the rate of elimination is directly proportional to drug concentration

Question 35

What is zero order kinetics?

Answer 35

The rate of elimination remains constant, independent of plasma concentration

Question 36

How can the rate of elimination be calculated?

Answer 36

Cp x Cl (Plasma concentration, Cp Clearance, Cl)

Question 37

How can the rate of elimination be calculated from a graph?

Answer 37

Given by the tangent to the curve | The higher the plasma concentration, the steeper the curve

Question 38

What are the units for rate of elimination?

Answer 38

mg/min

Question 39

What is CSS?

Answer 39

Plasma steady-state concentration

Question 40

How many half lives (roughly) does it take for a drug to reach CSS?

Answer 40

5

Question 41

Which surface of the cell membrane has a negative potential?

Answer 41

Inner surface

Question 42

Which direction does sodium move across a membrane?

Answer 42

Into the cell

Question 43

Which direction does potassium move across a membrane?

Answer 43

Out of the cell

Question 44

What is the resting potential of the cell membrane?

Answer 44

-70mV

Question 45

What causes the upstroke of the neuronal action potential?

Answer 45

Opening of Na+ channels causing influx of Na+ and rapid depolarisation

Question 46

What causes the downstroke of the neuronal action potential?

Answer 46

K+ opening and Na+ closing

Question 47

What is the absolute refractory period?

Answer 47

The period of the action potential in which no stimulus, however strong, can illicit a second action potential

Question 48

What is the relative refractory period?

Answer 48

The period in which a stronger than normal stimulus may illicit a second action potential

Question 49

How does the action potential move along an unmyelinated nerve fibre?

Answer 49

Smoothly & continuously

Question 50

How does the action potential move along a myelinated nerve fibre?

Answer 50

Jumps from one node of Ranvier to the next along the myelinated sheath