Pharmacokinetics

Question 1

What are the factors affecting Drug absp/Bioavailability

Answer 1

• Drug factors (physiochemical properties, lipophilic, dosage form, solid, liquid)
• Gatric emptying rate, GI motility
• Disease state
• Other factors (Interaction with other drugs/food)

Question 2

Where is the main site of Drug absp

Answer 2

Small intestines

Question 3

Why small intestine is the main site of absp

Answer 3

Large SA, Good blood flow, Long residence time (~4h)

Question 4

Definition of bioavailability (F)

Answer 4

A measure of the drug available to the systemic circulation over time after administration (usually oral).

Question 5

How to calculate F

Answer 5

AUC (route of administration.) / AUC (IV)

Question 6

Definition of PK

Answer 6

The action of the body to the drug which determines its concentration at the receptor site.

Question 7

Why oral admin has low F

Answer 7

Incomplete absp
presystemic metabolism (First pass metab.)

Question 8

What is the formula of Vd

Answer 8

Drug dose / [drug]plasma

Question 9

What are the factors affecting Drug distribution

Answer 9

• body size
• Lipid solubility of drug
• protein-binding in tissues vs plasma
• Disease start that alter physiology

Question 10

What are the factors affecting drug metabolism

Answer 10

• Delayed entry into the liver
• CYP enzyme inhibition by drugs (increase)
• CYP enzyme induction by drugs
• ethnicity/ genetics
• age , pathology

Question 11

Major site of drug excretion

Answer 11

Kidney

Question 12

Formula of Clearance

Answer 12

( [Drug]urine x Volurine/min ) / [drug]plama

Question 13

Definition of renal clearance

Answer 13

Volume of blood cleared of drug appearing in urine per unit time

Question 14

Effects of Drug metabolism

Answer 14

Metabolic inactivation, metabolic bioactivation, metabolic toxicity