Pharmacokinetics

Question 1

What is pharmacokinetics?

Answer 1

The movement of drugs in and the alteration of the drug by the body

Question 2

List the pharmacokinetic processes?

Answer 2

Absorption
Distribution
Metabolism
Elimination

Question 3

List the pharmacokinetic variables?

Answer 3

Bioavailability
Volume of distribution
Half life
Clearance

Question 4

Absorption is to?

Answer 4

Bioavailability

Question 5

Distribution is to?

Answer 5

Volume of distribution.

Question 6

Metabolism is to?

Answer 6

Half life

Question 7

Excretion is to?

Answer 7

Clearance.

Question 8

What is absorption??

Answer 8

Movement of drugs from site if administration to systemic circulation.

Question 9

What are the factors that affect absorption?

Answer 9

1. Biological membranes
2. Lipid-water solubility
3. Physical/dosage forms
4. Molecular and particle sizes
5. Concentration
6. Degree of ionisation and pH
7. Chemical nature and route of admin
8. Area of absorptive surface
9. Vascularity of absorbing surface.
10. Gi motility
11. Diseases
12. Presence of other substances.

Question 10

What is bioavailability?

Answer 10

The percentage or fraction or portion of administered dose that reaches systemic circulation in an unchanged form irrespective of the route of drug administration.

Question 11

What is distribution??

Answer 11

The passage of drugs from systemic circulation to other tissues that initially had no drug.

Question 12

What are the factors that influence distribution?

Answer 12

Lipid solubility.

Ionisation at Physiological pH.

Extent of binding to plasma and tissue protein.

Presence of tissue specific transporters.

Difference in regional blood flow.

Question 13

What is volume of distribution?

Answer 13

It is the apparent volume of drug that is distributed to provide the same conc as is in the blood plasma.

Question 14

What is drug metabolism?

Answer 14

It’s the chemical alteration of drugs in the body.

Question 15

What are the sites of metabolism?

Answer 15

Liver
Kidney
Lungs
Plasma
Placenta
Testis

Question 16

List examples of hydrophilic drugs

Answer 16

Streptomycin
Neostigmine
Pancuronium

Question 17

What are the phases of metab?

Answer 17

Phase 1
Phase 2

Question 18

What is phase one reaction?

Answer 18

Addition of a small polar group to a drug molecule

Question 19

What is the most important phase 1 reaction?

Answer 19

Oxidation.

Question 20

List the oxidation reaction enzymes?

Answer 20

Monoxygenases

Cytochrome p450 heme protein

Cytochrome p450 reductase

Nadph

Question 21

In Cytochrome p450, the 1st number, alphabet and 2nd number represents?

Answer 21

1st number-family

Alphabet- sub family

2nd number- isoenzyme

Question 22

About CYP3A4??

Answer 22

Found in the liver, intestine and kidney.

Metabolises 50% of drugs.

Most important CYP in metabolism.

Question 23

About CYP2D6?

Answer 23

2nd most important.

Metabolises 20-25% of drugs.

Question 24

About CYP2C8/9?

Answer 24

Metab of frequently prescribed medications. E.g antidiabetics, anticoagulants (warfin), analgesics (ibuprofen)

Question 25

About CYP2C19?

Answer 25

Metab of omeprazole.

Question 26

About CYP1A1/2?

Answer 26

Theophylline

Question 27

What are the reduction reaction enzymes?

Answer 27

NADPH CYTOCHROME-c-reductase Nitro reductase Keto reductase

Question 28

What is hydrolysis??

Answer 28

It is the breakdown of drug via taking a molecule of water

Question 29

Which enzymes are involved in hydrolysis??

Answer 29

Carboxylesterases Hydroxylases Amidases Peptidases

Question 30

What is cyclization?

Answer 30

Formation of a ring structure in a drug molecule with a straight chain

Question 31

Examples of drugs metabolised by cyclization include?

Answer 31

Proguanil.

Question 32

What is decyclization?

Answer 32

It is a process where the ring structure of a drug is opened up.

Question 33

Examples of drugs metabolised by decyclization?

Answer 33

Barbiturates Phenytoin

Question 34

Examples of phase II reactions include?

Answer 34

Glucoronide conjugation. Glutathione conjugation. Methyl, acetyl and amino conjugation.

Question 35

Glucoronide conjugation is characterised by?

Answer 35

UDP gluconosyl transferase.

Question 36

Sulfate conjugation is characterised by?

Answer 36

Sulfotransferase.

Question 37

Which drugs undergo glucoronide conjugation?

Answer 37

Drugs with hydroxyl or carboxyl acid groups.

Question 38

Which drugs undergo sulfate conjugation?

Answer 38

Drugs with phenolic group.

Question 39

Glutathione conjugation is catalysed by?

Answer 39

Glutathione - s- transferase. It is important in paracetamol overdose.

Question 40

What is first pass metabolism?

Answer 40

Metabolism of a drug during its passage from the site of absorption to systemic circulation.

Question 41

What are the sites of first pass effect?

Answer 41

Intestine, liver, lungs, skin

Question 42

What are are examples of drugs that have high first class metab?

Answer 42

Testosterone, salbutamol, hydrocortisone.

Question 43

What are the types of drug metabolising enzymes?

Answer 43

Microsomal enzymes. Non Microsomal enzymes.

Question 44

What are microsomal enzymes?

Answer 44

These are enzymes produced in the smooth ER of the kidney, liver, GIT. E.g monoxygenases, CYP450 They are involved in phase one reaction and glucuronide conjugation.

Question 45

What are non microsomal enzymes?

Answer 45

They are produced in cytoplasm and mitochondria. E.g oxidases, amidases, esterases. Catalyse most of phase II reactions except glucuronide rxn

Question 46

Enzyme activity is increased due to the increased synthesis of CYP450. T/F

Answer 46

True.

Question 47

What is half life?

Answer 47

It's the time taken for plasma conc of drug to be reduced to half of its original conc.

Question 48

Drugs with which molecular weight are excreted in bile?

Answer 48

>300

Question 49

Examples of drugs excreted in the bile include?

Answer 49

Erythromycin, refampicin, tetracycline, vercuronium.

Question 50

List the channels of excretion?

Answer 50

Urine Faeces Sweat Exhaled air Saliva Breast milk

Question 51

What is clearance of drug?

Answer 51

Theocratical vol of plasma from which the drug is completely removed in unit time.