Absorption and Distribution

Question 1

Factors affecting drug distribution

Answer 1

1. Regional differences in blood flow
2. Tissue mass
3. Transport mechanisms
4. Permeability characteristics
5. Ion trapping
6. Binding to protein

Question 2

ADME

Answer 2

Absorption
Distribution
Metabolism
Excretion

Question 3

Measurements of [drug] in plasma

Answer 3

For most drugs the concentration of drug at its site of action is related to the concentration in systemic circulation

Question 4

Absorption

Answer 4

The processes by which drugs move from their site of administration to the plasma

Question 5

Ionization

Answer 5

Weak acids non-ionized at low pHs
Weak bases non-ionized at high pHs
Non-ionized form is better absorbed through lipid membranes
Can be trapped in compartments of opposing characteristics (ie, weak bases more concentrated in acidic environment)

Question 6

Bioavailability

Answer 6

Fraction of administered dose that reaches the systemic circulation in its active form
(oral doses may be higher than parenteral doses because of reduced bioavailability)

Question 7

Volume of Distribution

Answer 7

Measure of how evenly distributed a drug is in the body
Is a theorectical volume of fluid into which the total drug administered would have to be diluted to produce the concentration in plasma