Learning Drug Interactions

Question 1

What are the CYP inducers? (PS PORCS)

What are the CYP inhibitors? (GPACMAN)

What happens between Valproate and Lamotrigine?

Answer 1

Phenytoin, Smoking, Phenobarbital, Oxcarbazepine( eslicarbazepine), Rifampin(rifabutin, rifapentine), Carbamazepine(auto inducer), St. John’s Wort. Increase levels of active prodrug.

Grapefruit Juice, Protease inhibitors(don’t miss ritonavir), Azole antifungals, Cyclosporine(cimetidine, cobicistat), Macrolides(not azithromycin), Amiodarone(dronedarone), Non-DHP CCB’s(diltiazem and verapamil).

Valproate inhibits lamotrigine metabolism(use starter kit)

Question 2

What happens between MAOI’s and tyramine rich foods?

What are your common CYP3A4 substrates?

What are common CYP2D6 substrates?

Answer 2

Can cause hypertensive crisis due to increase NE.

Analgesics, Anticoagulants, Antidiabetic drugs, Antiplatelets and cardiovascular drugs, immunosuppressants, statins, key HIV drugs, PDE-5 inhibitors.

Analgesics, Antipsychotics/antidepressants, OTHERS

Question 3

What drugs can cause ototoxicity?

Which drugs increase Digoxin levels?

Does gingko bilboa increase bleeding risk and affect INR?

Answer 3

Aminoglycosides, Cisplatin, Loop Diuretics, Salicylates, Vancomycin.

Quinidine, Verapamil, Erythromycin, Clarithromycin, Itraconazole, Cyclosporine, Propafenone, Spironolactone.

It does NOT affect INR but does increase bleeding risk.

Question 4

Does induction or inhibition have a lag effect?

Answer 4

Induction