Drug Interactions - Quiz 2 Flashcards
What is pharmacodynamics?
The effect or change that a drug has on the body
What drugs are affected by coadminstration with polyvalent cations?
Quinolones, tetracyclines, levothyroxine, bisphosphonates
What is pharmacokinetics?
The effect the body has on the drug
What is the primary enzyme expressed in the liver?
CYP450
What drug blocks the renal excretion of penicillin?
Probenacid
What are prodrugs?
Inactive drug that is converted by CYPs to an active drug
What are the benefits of prodrugs?
- INcrease bioavailability
- Prevent drug abuse
What is the activity of prodrugs in the presence of CYP inhibiutors and inducers?
Inhibitors: concentration of active drug decreases
Inducers: concnetration of active drugs inrease
What are the most common CYP inhibitors?
Grapefruit
Protease Inhibitors
Azole
Cyclosporine, cobicistat
Macrolides (clarithromycin and erythomycin)
Amiodarone
Non-DHP CCBs (diltiazem and verapamil)
What are the common CYP inducers?
Phenytoin
Smoking
Phenobarbital
Oxcarbazepine
Rifampin
Carbamazepine
St John’s wort
How long in the lag time when an inducer has been discontinued?
2-4 wks
Common Pgp substrates?
Anticoagulants: apixaban, rivaroxaban
CV drugs: digoxin, diltiazem, verapamil
Immunosuppressants: cyclosporine, tacrolimus
Colchicine
Common pgp inducers?
Carbamazepine, phenobarbital, phenytoin, rifampin, St Johns
Common pgp inhibitors?
CV: amiodarone, diltiazem, verapamil
HIV: cobicistat, ritonavir
Cyclosporine
When adding warfarin to amiodarine what do you need to adjust? Vice versa?
Warfarin at low dose ≤5 mg
Decrease warafarin dose by 30-50% depending on INR