Pharmacokinetics

Question 1

what is pharmacokinetics?

Answer 1

the study of what the body does to a drug

Question 2

What does ADME stand for?

Answer 2

A - absorption (how drug gets into body)
D - distribution
M - metabolism (how body chemically modifies drug)
E - excretion (how the body removes drug)

Question 3

What is the C-MAX?

Answer 3

Maximum concentration of drug in body = top point of the graph

This can help predict therapeutic benefits and the likelihood of side effects

Question 4

What is T-MAX

Answer 4

The time in which C-MAX occurred

Question 5

What is the half life of a drug

Answer 5

time it takes to remove half of the current concentration of drug from the body

Question 6

What is the area under the curve on a drug graph

Answer 6

total exposure to drug that the body receives

Question 7

What is the definition of absorption?

Answer 7

movement of a drug across a biological membrane from
the site of administration to the systemic circulation

Question 8

what is absorption dependent on

Answer 8

-Lipid
solubility/ionisation
-Solubility
-Concentration gradient
-Bioavailability
-Molecular size
-Blood flow
-Membrane surface area
-Membrane permeability

Question 9

What is ionisation?

Answer 9

atom or molecule with a net charge

ionisation = adding H+

Question 10

Drugs exist in BOTH ionised and unionised forms (often weak base or weak acid)

more H+ = more acidic

Answer 10

Ionised cannot pass through phospholipid bilayer as they have a ‘shell’ of water molecules

Question 11

Water soluble drugs = ionised

Answer 11

Lipid soluble = unionised drug

*drugs are only absorbed if they are unionised

Question 12

What is bioavailability?

Answer 12

the proportion of the unchanged drug that passes into the systemic circulation

Question 13

what is first-pass metabolism

Answer 13

orally administered drugs undergo pre-systemic metabolism in the liver

Question 14

what is distribution?

Answer 14

reversible transfer of a drug between one location to another

as most drugs are very small molecular size, they leave the circulation capillary filtration to act on the tissue

Question 15

What affects drug distribution?

Answer 15

-Blood supply
-Capillary permeability
-Lipid solubility
-Tissue binding
-Tissue-specific barriers

-Protein binding

Question 16

What protein is the primary protein involved in plasma protein binding of drugs

Answer 16

Albumin

Question 17

Drugs bound to albumin cannot pass through vascular wall

Answer 17

Correct

*see notes for further details

Question 18

FACT

Answer 18

less albumin = more free drug = increased pharmacological effect

Question 19

FACT

Answer 19

there is a condition called hypoalbuminaemia = low levels of albumin = increased pharmacological effect of drugs

Question 20

Why do you have to be careful with hepatic impairment with certain drugs?

Answer 20

increased risk of accumulation and toxicity due to decreased protein binding in hepatic impairment

Question 21

When drug is not highly bound to plasma proteins

Answer 21

= more is eliminated

Question 22

What is half life?

Answer 22

time it takes for one half of the drug to be
eliminated by the body

Drug half life is variable and can be long or short

 Subsequent doses are given to raise the
concentration levels to a peak
 In theory, the optimal dosage interval between
drug administration is equal to the half-life of the
drug

Question 23

What is the therapeutic threshold?

Answer 23

minimal amount of drug required to produce the desired response