Pharmacokinetics

Question 1

What are the 4 fundamentals of pharmacokinetics?

Answer 1

Absorption
Distribution
Metabolism
Excretion

Question 2

What is absorption?

Answer 2

Movement of a drug into the blood stream

Question 3

What are the routes of absorption? (9)

Answer 3

Oral
Buccal
Inhalation
Transdermal
Topical
Rectal
IM
IV
SC

Question 4

How are oral drugs absorbed?
(2)

Answer 4

Using 1st pass metabolism
By the liver

Question 5

How is buccal absorbed? (2)

Answer 5

Avoids 1st pass metabolism
High blood flow

Question 6

How is rectal absorbed?

Answer 6

Reduced 1st pass metabolism

Question 7

How is inhalation absorbed? (2)

Answer 7

Large surface area
High blood flow

Question 8

How are topical drugs absorbed? (2)

Answer 8

Has lower therapeutic effect
Has decreased systemic efficacy

Question 9

How are transdermal drugs absorbed? (2)

Answer 9

Smaller molecules, which rely on lipid permeation
Reduced systemic effects

Question 10

How are IV drugs absorbed? (4)

Answer 10

Rapid effect
100% bioavailability
Avoids 1st pass metabolism
Bypasses absorption barriers

Question 11

How is IM absorbed? (2)

Answer 11

Blood flow dependant
avoids 1st pass metabolism

Question 12

How are SC drugs absorbed? (2)

Answer 12

Slow absorption
Blood flow dependant

Question 13

What are the 6 formulations of drugs?

Answer 13

Soluable
Dispersible
Suspensions
Film coated
Slow release
Capsule

Question 14

Factors which affect oral absorption? (8)

Answer 14

Ph
Gut activity
Strength of dose
Solubility of drug
Permeation
Blood flow to GI tract
Gastric emptying time
Physiochemical factors

Question 15

What are the 4 mechanisms of drug permeation?

Answer 15

Aqueous diffusion
Lipid diffusion - (most common)
Facilitated diffusion
Pinocytosis

Question 16

How does diffusion work? (4)

Answer 16

Works best on short distances
Small molecules
Big concentration
Gradient

Question 17

What factors affect distribution? (5)

Answer 17

Lipid solubility
Protein binding - (most important)
Blood flow
Molecular size
Ph

Question 18

Whats the most important molecule for binding?

Answer 18

Albumin

Question 19

Which molecules can bind?

Answer 19

Only free molecules

Question 20

Which molecules work better for slow release?

Answer 20

Larger lipid molecules

Question 21

Which molecules work best for quick release?

Answer 21

Hydrogen based smaller molecules

Question 22

What is volume distribution?

Answer 22

Ability to cross cell membrane
Lipid drugs (lg) 1-10l/kg
Water soluble (sm) 0.1-1 l/kg

Question 23

Which drugs are easier to distribute?

Answer 23

Lipid soluble

Question 24

How are drugs metabolised? (5)

Answer 24

Most metabolism happens in the liver
Converts drugs into a more water soluble product
Therapeutic effect decreases after being metabolised
Main enzyme is cytochrome p450
Often divided into 2 phases - oxidation and conjugation

Question 25

What are metabolites?

Answer 25

They are toxic but the side effects are the ones used

Question 26

What happens in an overdose situation?

Answer 26

There are not enough glutathione to detoxify the metabolites

Question 27

What long term conditions can reduce the livers ability to metabolise drugs?

Answer 27

HF and shock

Question 28

What is an inhibitor in relation to metabolism?

Answer 28

prolongs the action of a drug

Question 29

what is an inducer in relation to metabolism?

Answer 29

Shortens the action of a drug

Question 30

What does a blocker do in relation to metabolism?

Answer 30

Acts on non-microsomal enzymes

Question 31

What is the main way drugs are excreted? (2)

Answer 31

Glomuler filtration and tubular excretion Relies on hydrostatic pressure

Question 32

What is meant by tubular excretion?

Answer 32

The kidneys are more specific in what it excretes.

Question 33

What happens to drugs excreted by the bile duct?

Answer 33

They can remain active in the gall bladder which can cause enterohepatic re-uptake

Question 34

Name all the ways drugs can be excreted. (6)

Answer 34

GI tract Kidneys Lungs Sweat Saliva Breastmilk

Question 35

What is meant by clearance?

Answer 35

clearance is the sum of all elimination routes ie, the amount of drug leaving the body at any given time

Question 36

What are the orders of elimination? (2)

Answer 36

zero order - 5% of drugs, cant be sped up First order - 95% of drugs, rate is proportionate to excretion

Question 37

Which order of elimination is the main one used?

Question 38

What processes are used during clearance?

Answer 38

Metabolism and excretion

Question 39

What makes drugs easier to excrete?

Answer 39

Metabolising them from lipid to water soluble

Question 40

What drug is excreted by the kidneys without being metabolised first?

Answer 40

Aminoglycoside antibiotics