pharmacology 2 drug kinetics and toxicity

Question 1

routes of drug administration

Answer 1

IV
oral
SC
IM
inhaltion
rectal
transdermal

Question 2

gastric emptying

Answer 2

gastric emptying crital for drug absorption

Question 3

bioavailability

Answer 3

fraction of unchanged drug reaching the system circulation following any route of adminstration

Question 4

what does bioavailbiliyt depend on

Answer 4

absorption
first pass metabolism
food

Question 5

distribution is and depends on

Answer 5

physiochemical properties of the drug
-molecular size
oil/water partition coefficient
degree of ionisation that depends on pKa
protein binding

Question 6

plasma proteins

Answer 6

1) Albumin
- mainly acidic drugs bind
2) A1- acid glycoprotein
- basic drugs mainly bind

Question 7

what happens with plasma proteins if we have more than 1 drug

Answer 7

Displacement of one acid drug by another drug results in transient increase of free drug concentration

• • increase in the free drug concentration results in increase in the clearance of the free drug form the circulation

Question 8

rate of drug distribution depends on

Answer 8

perfusion limited tissue distribution (immediate equilibrium of drug in blood and tissue, only limited by blood flow)
permability rate limitations or membrane barriers

Question 9

blood brain barreri

Answer 9

prevents chemical molecules entering the brain
protects membrane
can only enter CNS via carriers or lipid soluble
acid brain cells trap ionised weak base

Question 10

placental barrier

Answer 10

lipid soluble and unionised can easily pass the barrie
most bacteria are blocked
material antibodies can cross

Question 11

activation of drug metabolism leads to …

Answer 11

increase in pharmacolgical
increase toxicity
and vice versa for deactivation

Question 12

phases of drug metabolism

Answer 12

phase 1
introduction or exposure of polar group via oxidation reduction or hydrolysis
Phase 2
attachment of endogenous molecule to drug or phase 1 metabolite

Question 13

phase 1

Answer 13

if metabolites are sufficiently polar can be excreted

toxic compounds may be created

Question 14

phase 1vs2

Answer 14

phase 1 usually produces more active compounds than phase 2

Question 15

what is conjugation

Answer 15

formation of a bigger product

Question 16

enzymes involved in phase 1 of drug metabolism

Answer 16

oxidation, cytochrome P450

in the liver

Question 17

enzymes involved in phase 2

Answer 17

transferases

eg glucoronyl

Question 18

drug elimination

Answer 18

most can undergo renal elimination (water soluble ionised)

non polar species /unionised via binary excreateion

Question 19

bilary excreation

Answer 19

bile secreted by hepatic cells of liver

bile important in digestion and absorption of fats

Question 20

factors which influence secretion in the bile

Answer 20

• Molecular weight)
• Polarity (higher polarity more bile excretion)
• Nature of biotransformation
• Gender, diseases, drug interactions

Question 21

how may pharmacological effect of a drug be prolonged

Answer 21

enterohepatic recycling from reabsorption from the gut

Question 22

nephron

Answer 22

connects blood to final product
bowmans capsule surrounds blood vessel
reaches proximal tubule
drugs can enter and secreted into nephrone

Question 23

excretion equation

Answer 23

filtraton+ secretion - reabsroption

higher the GFR
more likely drugs will enter nephron and be excreated

Question 24

clerance

Answer 24

rate of excretion

Question 25

therpeutic index

Answer 25

margin between teh therapeutic dose and toxic dose

Question 26

factors affecting metabolism of the drugs

Answer 26

high blood level conc of drug 
genetic polymorphisms
enviroment
disease
genetic 
age 
drug interaction

Question 27

genetic polymorphism -

Answer 27

CYP2D6 polymorphism poor metabolisers

Question 28

genetic polymorphism definition

Answer 28

Change in cytochromes