Drug disposition

Question 1

What is in a medicine?

Answer 1

active drug

excipients (inactive part of drug)

Question 2

What impacts can excipients cause?

Answer 2

bioavailability

duration of therapeutic effect

Question 3

What happens to oral drugs?

Answer 3

tablets> granules> fine particles > solution> absorption

Question 4

Site of absorption of drugs?

Answer 4

stomach

small intestines

Question 5

Required property of drug?

Answer 5

It has to be lipid soluble

Question 6

Absoption mechanisms of drugs?

Answer 6

passive diffusion
through aquaporins
facilitated diffusion
endocytosis

Question 7

What is facilitated diffusion?

Answer 7

Selective passage of substance down its concentration
gradient via protein channel
No ATP use
can be inhibited by antagonists

Question 8

What is active transport?

Answer 8

Movement of substance against its concentration gradient

ATP use

Question 9

What is drug distribution?

Answer 9

The distribution of drugs via blood stream into various body tissues

Question 10

What is the blood flow to liver?

Answer 10

680 mL/min/kg

Question 11

Blood flow to kidney

Answer 11

3333 mL/min/kg

Question 12

blood flow to CNS

Answer 12

615 mL/min/kg

Question 13

blood flow to myocardium

Answer 13

833 mL/min/kg

Question 14

blood flow to fat

Answer 14

25mL/min/kg

Question 15

blood flow to muscles and others

Answer 15

25mL/min/kg

Question 16

What is protein binding?

Answer 16

Binding of drug onto plasma proteins > only unbounded drugs can diffuse through membranes

Question 17

What is drug metabolism?

Answer 17

Enzyme mediated conversion of lipid soluble compound into water soluble compound

Question 18

Where does drug metabolism mostly occur?

Answer 18

Liver

Question 19

Other places for drug metabolism to occur?

Answer 19

kidney, GI tract, brain, lung, plasma

Question 20

What is phase I of drug metabolism?

Answer 20

Modification of drug structure to make them more water soluble and can cause drug to become more reactive than parent drug (pharmacological activation)

Question 21

What is phase II of drug metabolism?

Answer 21

It conjugates drugs to large molecules e.g. amino acids, sulphate groups, glucuronic acid
it causes pharmacological inactivation

Question 22

What is pharmacological inactivation?

Answer 22

The modification of drug structure which makes decreases receptor affinity and enhances excretion

Question 23

What can happen to drug metabolising enzymes?

Answer 23

they can be induced or inhibited

Question 24

What is drug excretion?

Answer 24

the removal of drug from the body via urine, faeces, lungs or skin

Question 25

What is drug half-life?

Answer 25

the time taken for amount of drug in body to decrease to half

Question 26

What is the importance of drug half-life?

Answer 26

Prevents drug interaction via allowing you know when one drug has be eliminated from body
important to determine how long a toxic concentration of drug will take to be decrease

Question 27

What is drug therapeutic window?

Answer 27

The range of drug dosage from minimum therapeutic concentration to minimum toxic concetration

Question 28

Consequences of renal and hepatic diseases on drugs?

Answer 28

Drug concentrations may reach toxic levels due to elongated half life time