Pharmacology

Question 1

What drugs alter Digoxin clearance, and what is the mechanism?

Answer 1

Clearance decreased due to increased MDR1 transporter activity

Drugs that cause this: amiodarone, dronedarone, quinidine, ritonavir, ranolazine

Question 2

St John’s Wort acts on which CYP, and in which way?

Answer 2

Induced 3A4

Ciclosporin is key drug that is metabolised more

Question 3

Celecoxib and Warfarin

Answer 3

Celecoxib inhibits CYP2C9, leading to raised s-Warfarin and this increased warfarin effect. Can double INR

Question 4

What transporter variant is associated with Imatinib resistance?

Answer 4

ABCG2

Question 5

Furosemide and Lithium

Answer 5

Furosemide will increase serum lithium levels

As will HCT

Question 6

Valproate and Lamotrigone

Answer 6

If used together, Lamotrigine needs dose adjustment

Question 7

Ciclosporin metabolism

Answer 7

CYP3A4 in liver
Metabolism also occurs in small intestine via same CYP3A4