LG 7.4 - PK 2 Antihistamines

Question 1

What is drug steady state? When would a patient usually reach this state?

Answer 1

• The point in a consistent dosing regimen where serum levels are no longer changing.
• After 4 half-lives worth of time.

Question 2

What are the 2 ways the liver can metabolize drugs?

Answer 2

• Termination of drug action: bio-inactivation, prepares it for excretion into bile and/or urine.
• Active metabolite(s) can be formed.

Question 3

What is a “prodrug”?

Answer 3

• an inactive parent drug which requires bio-activation (by liver).

Question 4

What is toxification?

Answer 4

• Metabolism causes drug to be toxic.

Question 5

What are the differences between phase 1 and phase 2 drug liver metabolism?

Answer 5

Phase 1:
- Involves cytochrom p450 (cyp) liver enzyme system.
Phase 2:
- conjugation step (with glucuronic acid, sulfate, etc)

Question 6

What happens to drugs as they become metabolized (biochemically)?

Answer 6

• Go from lipophilic -> hydrophilic, so that they can go from getting into cells -> getting excreted.

Question 7

What is meant by an enzyme inducer?

Answer 7

• These speed up the metabolism of other drugs.

Question 8

Describe enterohepatic recycling?

Answer 8

• After drug is processed by the liver and the conjugate is ready to be excreted, sometimes when it enters the small intestine there are bacteria that cleave the bond on the conjugate and the drug becomes active again.

Question 9

What is the role of the kidney in drug elimination?

Answer 9

• Important organ in getting rid of drugs.

- Can be filtered, secreted, and reabsorbed.