How Drugs Get Where They Are Going? (pharmacokinetics)

Question 1

What are the 4 aspects of pharmacokinetics?

Answer 1

▪️Absorption
▪️Distribution
▪️Metabolism
▪️Excretion

Question 2

Routes of administrations

Answer 2

▪️rectum 
▪️oral
▪️intravenous 
▪️subcutaneous 
▪️inhalers
▪️intramuscular

Question 3

What are the types of drug targeting?

Answer 3

▪️topical (local)
▪️enteral (delivered through GI but ends up system wide)
▪️parenteral (no delivered through GI but ends up system wide)

Question 4

Bioavailability of a drug

Answer 4

▪️the amount of drug that reaches he systemic circulation
-PO (oral drugs) must pass through intestinal wall and portal circulation before reaching blood (1st pass)
▪️= AUC oral/ AUC injected X 100

Question 5

What two things determine rate of absorption of a drug?

Answer 5

▪️time it takes for the concentration of the drug to reach its max in the blood (T max)
▪️maximum drug concentration (C max)

Question 6

What are the sites of metabolism?

Answer 6

▪️liver
▪️gut wall
▪️intestinal flora 
▪️lung 
▪️kidney

Question 7

CYP450

Answer 7

▪️ superfamily of haem containing proteins
-can be inhibited or induced by other drugs
▪️involved in metabolism of diverse intrinsic and extrinsic compounds
▪️has multiple isomers which makes it more difficult to avoid

Question 8

Sites of elimination of drug

Answer 8

▪️kidney
▪️liver
▪️sweat
▪️saliva 
▪️tears
▪️exhalation 
▪️breast milk

Question 9

Half life of a drug

Answer 9

▪️time it takes for the concentration of the drug to decrease by half in the blood

Question 10

Elimination half life of a drug

Answer 10

▪️time at which the drug is completely (93%) eliminated from the body
-5X the normal half life

Question 11

Steady state of a drug

Answer 11

▪️rate of drug administered = rate of elimination

• when the concentration of the drug plateaus
• 4.5-5 elimination half-lives