drug absorption

Question 1

what are the four basic factors determining drug pharmacokinetics?

Answer 1

Absorption
Distruption
Metabolism
Elimination

Question 2

define the process of absorption

Answer 2

movement of unchanged drug from the site of administration to the systemic circulation.

Question 3

true or false : There is always a correlation between plasma concentration of a drug and the therapeutic response.

Answer 3

true

Question 4

what is important when considering oral absorption

Answer 4

Amount of drug which enters the systemic circulation

Speed at which this happens

Question 5

what is Tmax

Answer 5

time to peak concentration

Question 6

what is Cmax

Answer 6

peak conc

Question 7

what is the AUC

Answer 7

area under the drug concentration- time curve

Question 8

what does increasing the dose do in regards to tmax and max

Answer 8

does not affect the time at which peak concentration is reached but does increase the peak concentration

Question 9

The more rapid the rate of absorption, the ……. the drug concentration peak.

Answer 9

earlier

Question 10

what is therapeutic range

Answer 10

A drug is active over a range of concentrations

Question 11

what is the therapeutic index

Answer 11

measure of the range at which a drug is safe and active.

Question 12

what allows us to estimate the amount of drug which reaches the circulation and which is available for action

Answer 12

AUC

Question 13

what are the factors affecting oral absorption?

Answer 13

Formulation
-Slow release preparations

Ability of drug to pass -physiological barriers

• Particle size
• Lipid solubility
• pH and ionisation

Gastrointestinal effects

• Gut motility
• Food
• Illness

First pass metabolism

Question 14

what is bioavailability?

Answer 14

the proportion of a drug or other substance which enters the circulation when introduced into the body and so is able to have an active effect.

Question 15

what are the different types of transport across membranes?

Answer 15

Passive diffusion
Filtration
Bulk flow
Active transport
Facilitated diffusion
Ion-pair transport
Endocytosis

Question 16

what is lipid-water partition coefficient

Answer 16

The ability of a drug to diffuse across a lipid barrier

Question 17

A drug that is highly lipid soluble will ……. diffuse across a cell membrane.

Answer 17

rapidly

Question 18

for active absorption what uptake of the brain is needed

Answer 18

levodopa

Question 19

what are gastrointestinal factors

Answer 19

Motility
Speed of gastric absorption will affect speed at which drug reaches site of absorption (most drugs are absorbed in small intestine).
Can be affected by other drugs, food/drink and illnesses (esp pain).

Food
Can enhance or impair rate of absorption.

Illness
Malabsorption (eg Coeliac disease) can increase or decrease rate of absorption
Migraine reduces rate of stomach emptying and therefore rate of absorption of analgesic drugs.

Question 20

when would you use rectual absorption

Answer 20

is sued for drugs which upst the stomach

Question 21

what are the considerations for mode of administration

Answer 21

Purpose and site of drug action

• Local absorption
• Avoid first pass metabolism

Disease effects
Patients ability to take medicine
Speed of action
Reliability of absorption