Pharmacology

Question 1

Pros and cons of IV drug administration.

Answer 1

Pros
Rapid immediate onset
Permits titration

Cons
Infection
Pain
Risk of adverse effects

Question 2

Pros and cons of IM drug administration.

Answer 2

Pros
Rapid onset
Shorter duration

Cons
Neurovascular damage
Pain
Infection

Question 3

Pros and cons of subcut drug administration.

Answer 3

Pros
Prolonged effect
Constant slow absorption

Cons
Pain
Infection
Delayed absorption in shock

Question 4

Pros and cons of enteral (oral/rectal) drug administration.

Answer 4

Pros
Convenient
Safe
Cheap

Cons
Absorption influenced by stomach contents
Gastric acid interferes with absorption
Uncooperative patients may not take

Question 5

Define bioavailability. What symbol expresses bioavailability?

Answer 5

Fraction of the administered drug which reaches systemic circulation.

Expressed as letter F
F=1 for IV drugs

Question 6

Describe factors affecting bioavailability

Answer 6

Molecular weight
Gastric pH
Grapefruit juice may increase bioavailability

Question 7

Define volume of distribution.

Answer 7

The apparent volume into which a known amount of drug must be dispersed to give the measured plasma volume

Question 8

What factors does the volume of distribution depend on?

Answer 8

Plasma protein and tissue binding
Molecular weight
Lipid solubility

Question 9

What is the volume of distribution used to determine?

Answer 9

Loading dose amount

Elimination half life, dosage interval

Question 10

Define clearance

Answer 10

Theoretical volume of plasma (blood etc) cleared of drug per unit time (mlmin-1)

Question 11

What is the half-life of a drug?

Answer 11

Time taken for serum plasma concentration to decrease by half

Question 12

What determines half-life?

Answer 12

Clearance and volume of distribution

VofD/clearance

Question 13

How many half lives does it usually take to clear a drug?

Answer 13

4-5

Question 14

What is the maintenance dose?

Answer 14

When rate in=rate out

Question 15

What is steady state?

Answer 15

The amount of drug administered is equal to the amount of drug eliminated within one dosing interval.

Question 16

How are half life and steady state related?

Answer 16

Drugs with a short half life reach steady state rapidly

Drugs with a long half life can take days to reach steady state.

Question 17

Name the 4 common signal transduction methods of action with regards to drugs.

Answer 17

Enzyme linked
G protein linked
Ion channel
Nuclear

Question 18

Define affinity.

Answer 18

Measure of propensity of a drug to bind to the receptor.

Question 19

Define potency.

Answer 19

Amount required to produce an effect of given intensity

Relative position of the dose-effect curve along the dose axis

Question 20

Define efficacy

Answer 20

Ability of a bound drug to change the receptor in a way that has an effect.

Question 21

Describe an agonist.

Answer 21

Drug which bind to a receptor and activated the receptor to produce a biological response

Has affinity and intrinsic action

Question 22

Describe an antagonist.

Answer 22

A drug which blocks a biological response by binding to a receptor.

Has affinity but no intrinsic activity

Question 23

Describe therapeutic index.

Answer 23

A comparison of the amount of a drug that causes a therapeutic effect to the amount that is toxic.