Pharmacokientics

Question 1

Define pharmacokinetics:

Answer 1

Study of the movement of a drug into and out of the body

Question 2

Define pharmacodynamics:

Answer 2

Study of the drug effect and the mecahisms of action “what the drug does to the body”

Question 3

What is the defination of pahrmacogenetics?

Answer 3

The effect of genetic variability on the pharmacokientics or dynamics of drugs on a indivdual

Question 4

What methods of drug delivery are described as enteral?

Answer 4

Oral, sublingual and rectal routes

Question 5

What are the methods of parental delivery?

Answer 5

All routes that are not GI, including intravenous, subcutaneous, transderaml, intermuscualr and intrathecal

Question 6

What is the bioavailability of a drug?

Answer 6

The fraction of a dose that finds it way into a body compartment- usually the circulation, or can be described as the relative amount of a drug that reaches the systemic circulation after it has overcome all the barriers to absorption

Question 7

What is the equation that is used to determine the bioavailbility?

Answer 7

The amount of the drug that reaches the systemic circultaiton/ the total amount of drug that is adminstered

Question 8

What are some of the factors that affect the bioavailability?

Answer 8

The factors that affect the absorption include the drug formulation the age, and food as some drugs are lipid soluble compared to water soluble, or vomiting and malabsorption, and the first pass metabolism

Question 9

What is first pass metabolism?

Answer 9

Any metabolism occuring before the drug enters the systemic circuatlion

Question 10

Where can first pass metabolism occur?

Answer 10

The gut lumnen, the gut wall and the liver

Question 11

What are the two key factors that affect drug disturbution in the body?

Answer 11

Protein binding, the volume of distrubtion, and the lipophility and the hdyophility of the drug.

Question 12

What are some of the proteins that a drug may bind to?

Answer 12

Albumin, globulins, lipoproteins, acid glycoproteins

Question 13

What are some of the factors affecting protein binding?

Answer 13

Hypoalbumenia, pregancy, renal failure and displacement by other drugs

Question 14

How can drug binding affect the disturbution of drugs in the binding in the body?

Answer 14

Drug that is not bound to plasma proteins is available for distrubiton to the tissues of the body.

Question 15

What is the apparent volume of disturbution?

Answer 15

Volume of distrubtion is a measure of how widely a drug is disturbtuted in body tissue, Vd- dose/ drug at to.

Question 16

What are some examples of drugs with a low volume of distrubution?

Answer 16

Ibuprofen, Sulphonureas and warafrin

Question 17

What are some examples of drugs with a high volume of distbution/

Answer 17

Digoxin, tricylcic antidepressants, and amiloride

Question 18

What are some of the factors that can affect the tissue disturbtion of a drug?

Answer 18

Sepcific receptor sites in tissue, regional blood flow, lipid solubaility, active transport, disease states, drug interactions

Question 19

What are the main enzymes used to carry out phase I metabolism?

Answer 19

Cytochrome P450 enzymes

Question 20

What are the chemical proccesses that happen in phase I metabolism?

Answer 20

Oxidation and reduction

Question 21

What are the main cytochrome P450 enzymes?

Answer 21

CYP2D6, 2C9, 2C19, 3A4

Question 22

What are some of the products that are metabolised by cytochrome P450 3A?

Answer 22

Metabolsim of calcium channel blockers, benzodiazpeines, HIV protease inhbitors, mast statins, and cyclosporins, and non sedating antihistamines

Question 23

What are some of the inhbitoris of CYP 3A?

Answer 23

Antifungals, includ petonacoazole, fluconoacole, citmineding, macrolides, and erthorymycin, and grapefruit juice,

Question 24

What are some of the inducers of CYP3A?

Answer 24

Carbamezapine, phenytonin, rifampacin, ritonvir and st johns wort

Question 25

What does CYP 2C9 metabolise?

Answer 25

most NSAIDS, swarafin, phenyonting, tolbutamine.

Question 26

What is CYP 2C9 inhibitied by?

Answer 26

Fluconazole

Question 27

What is CYP 2C9 induced by?

Answer 27

Carbamezapine and ethanol

Question 28

What is metabolised y CYP 2C19

Answer 28

Diazpram, pehnytonin, omperazole

Question 29

What inhibitisCYP 2C19?

Answer 29

Ketocanzole, and omeprazole

Question 30

What is the main route of drug elimination?

Answer 30

The kidney

Question 31

What are the three processes that determine the renal elimination of drugs?

Answer 31

The three processes are glomerular filtration, passive tubular reabsorption, active tubular secretion

Question 32

How is penecillin excreted in the kidney?

Answer 32

Penecillin undergoes active secretion

Question 33

How does the GFR relate to clearance?

Answer 33

If the GFR is reduced the clearance is reduced, the hfl life of a drug is inversely proportional to the clearance

Question 34

Describe first order kinetics?

Answer 34

The rate of elimination is proportional to the drug level, and a constant fraction of the drug is eliminated in the unit time

Question 35

Describe zero order kienetics

Answer 35

The rate of elimination is a constant

Question 36

What is the clinical significance of zero order drugs?

Answer 36

Zero order drugs are more likely to result in toxicity, and small dose changes may actually produce large increments in dose.

Question 37

What is the CpSS?

Answer 37

The steady state concentration in the plasma

Question 38

What are some of the clinically significant results of paracetamol metabolism?

Answer 38

P$%) oxidation produces NAPQI which undergoes conjugation with glutathione, and this process can become saturated

Question 39

How do you calculate the loading dose?

Answer 39

Vd x CpSS

Question 40

How do you calculate the half life of a drug?

Answer 40

0.693 x Vd/ CL

Question 41

What is the multi compartment model?

Answer 41

Most drugs do not remain in the plasma, and therefore disturbution occurs in two or more compartments, and the equilibrium between the compartments are not equal