2. Pharmacokinetics

Question 1

Absorption (define)

Answer 1

Process of transfer of a drug from the site of administration into the blood

Question 2

Variables affecting drug absorption (6)

Answer 2

1. nature of absorbing surface
2. blood flow
3. solubility
4. formulation
5. routes of administration
6. ionisation

Question 3

Distribution (define)

Answer 3

process of reversible transfer of a drug between one location and another

Question 4

Plasma protein binding (define)

Answer 4

reversible process that decreases the concentration of free drug in circulation

Question 5

Blood brain barrier

Answer 5

allows highly lipid soluble drugs to pass through

Question 6

Placental barrier

Answer 6

membranes that separate blood vessels of the mother and foetus

Question 7

Vd

Answer 7

volume of body water in which a drug appears to be dissolved in after it has distributed throughout the body

Question 8

Metabolism

Answer 8

process of chemical modification of a drug, carried out by enzymes

Question 9

Bioavailability

Answer 9

the proportion of the administered dose of a drug that reaches the systemic circulation in tact

Question 10

Bioavailability - what can it be affected by

Answer 10

1. Pharmaceutical formulation
2. Absorption across the gut
3. First pass metabolism in the liver

Question 11

Hepatic First Pass Effect

Answer 11

1. Absorption of drug from GIT –> goes to hepatic portal system
2. takes digested contents to liver for processing
3. variable amount of drug reaches systemic circulation

Question 12

Excretion

Answer 12

irreversible loss of chemically unchanged drug from the body in urine, bile, expired air, faeces

Question 13

Elimination

Answer 13

irreversible loss of drug from body by processes of metabolism and excretion

Question 14

Drug half life

Answer 14

time required for the amount of drug in the body to decrease by 50%

Question 15

Clearance

Answer 15

ability of an individual organ or the body to eliminate a drug