pharmokinetics

Question 1

what is clinical pharmacology

Answer 1

science of drugs and their use in humans

Question 2

what is bioavailability

Answer 2

the proportion of administrated drug which reaches the systemic circulation unchanged

Question 3

what type of drug administration achieves 100% bioavailability

Answer 3

intravenous injection

Question 4

what is the most common route of drug administration

Answer 4

oral route

Question 5

in the oral route what does absorption rate depend on

Answer 5

GI transit

Question 6

what are the mucosal routes of drug administration

Answer 6

nasal, eye, vaginal, rectum,

Question 7

what route of administration avoids first pass metabolism

Answer 7

inhalation, mucosal routes, transdermal, intravenous subcutaneous and intramuscular injections

Question 8

what is pharmacokinetics

Answer 8

study of drug movement within the body

Question 9

what is pharmacodynamics

Answer 9

study of drug effects and metabolism of action

Question 10

what are the four stages of pharmacokinetics

Answer 10

absorption, distribution, metabolism, excretion

Question 11

For an orally- administrated drug to reach

systemic arterial circulation intact, the drug must :

Answer 11

• cross the GI tract

- avoid metabolism by the GI tract and liver

Question 12

factors affecting GI drug absorption rates

Answer 12

1. Surface area and blood flow
2. Gastrointestinal motility
3. Malabsorptive tates
4. food type

Question 13

what is first pass metabolism

Answer 13

the extent of metabolism occurring BEFORE the drug enters the systemic circulation. Occurs in gut lumen, gut wall and liver

Question 14

after absorption orally-administrated drugs enter what system

Answer 14

portal system

Question 15

rate and distribution of a drug are determined by

Answer 15

• the ability of the drug to pass through membranes
• lipid solubility Of the drug
• Binding of the drug to plasma proteins
• active transport across cell membranes
• Presence of other drugs in the body

Question 16

what is drug distribution

Answer 16

process by which drugs are transferred from systemic circulation to tIssues

Question 17

what is the volume of distribution, what is the effect on lipid solubility and protein-bound on VD? What are the impacts of high VD?

Answer 17

the amount of water h20 which the drug would have to be added to give the same concentration as in plasma

lipid solubility: increases VD
protein-bound: decreases VD

high VD , causes sequestration of fat cells = long half-life

Question 18

a high Vd can indicate what

Answer 18

sequestration in body fat and Long drug half- life

Question 19

what type of drug can transverse membranes to accesss cells and targets

Answer 19

non-protein bound

Question 20

do drugs bind reversibly or irreversible to plasma proteins

Answer 20

reversible without causing damage

Question 21

what are the criteria for protein binding to significantly affect drug distribution

Answer 21

1. protein-bound proportion must constitute 90% Off total drug in the plasma
2. extent Of the distribution of the drug to the tissues must be the same
3. High protein binding can dramatically Increase half- Life

Question 22

what is causes protein displacement

Answer 22

co-adminstrating drugs

Question 23

protein displacement is very important to what

Answer 23

drug distribution, effect and quality

Question 24

what organ is a major site of drug metabolism

Answer 24

liver

Question 25

what happens during phase 1 of absorption

Answer 25

products produced tend to be more chemically reactive and often more toxic than the parent drug

Question 26

what happens during phase 2 of absorption

Answer 26

drug produces chemically polar products which are cleared by the kidney

Question 27

examples of factors affecting drug metabolism

Answer 27

Liver disease - genetic polymorphisms in drug metabolism - advancing age - genetic polymorphisms in drug metabolising enzymes - competition between different drugs for some metabolising enzymes

Question 28

what are the main routes of excretion

Answer 28

kidney via the urine

Question 29

what are elimination kinetics in the rate of elimination

Answer 29

amount of drug eliminated from the body/unit of time

Question 30

what are first-order kinetics in drug elimination, what is an important parameter to measure this?

Answer 30

drug concentration decreases exponentially over time. drug elimination half-life curve

Question 31

what can be determined from elimination curves

Answer 31

drug half-life

Question 32

what is half life

Answer 32

the time it takes for the plasma drug concentration to halve, determined by an elimination curve

Question 33

what enzymes are important in phase 1 absorption

Answer 33

cytochrome P450

Question 34

what is protein binding, what is the affect on half-life

Answer 34

reversible has no effect on drug function, protein-bound however cannot cross the membrane increasing half-life

Question 35

what is the half-life of paracetamol, atenolol, warfarin, chloroquine

Answer 35

2 hours 6 hours 2 days 6 weeks

Question 36

what is the effect of liver disease on bioavailability

Answer 36

patients have higher bioavailability because the drug is not metabolised within the lives. Drug doses and timing calculations will need to be altered.