Module 1: CYP450 Flashcards
How does CYP450 induction work?
CYP450 induction increases the synthesis or decreases the degradation of cytochrome P450 enzymes. This speeds up the conversion of drugs to inactive metabolites, which reduces the amount of the drug in the plasma.
This results in the reduced therapeutic effect of a co-administered drug.
True or False: CYP450 enzyme induction can lead to increased metabolism of drugs.
True
What is the effect of rifampin on CYP450 enzymes?
Rifampin (used in tx of TB) induces multiple CYP450 enzymes, increasing the metabolism of co-administered drugs such as propranolol hydrochloride.
Multiple Choice: Which of the following drugs is known to induce CYP3A4? A) Ketoconazole B) St. John’s Wort C) Fluoxetine
B) St. John’s Wort (tx of mild to moderate depresstion) - which decreases the bioavailability of verapamil (Ca+ channel blocker).
Short Answer: What is a common clinical strategy to manage drug interactions caused by CYP450 induction?
Monitor drug levels and adjust dosages accordingly.
How does CYP450 inhibition work?
A CYP450 inhibitor from one drug, binds to the CYP450 enzyme, preventing it from metabolizing other drugs or substances, potentially leading to increased drug levels in the body d/t decreased breakdown.
What are the three types of inhibition?
- Inhibition = a drug inhibits the CYP450 enzyme that metabolizes another drug.
- Reversible inhibition = the most common type of drug-drug interaction, where drugs compete for the enzyme.
- Irreversible inhibition = A stable complex forms between the drug and the enzyme, permanently reducing the enzyme’s activity.
Fill in the blank: Inhibition of CYP450 enzymes can lead to increased levels of _______ in the bloodstream.
drugs
Name a drug which inhibits the metabolism of warfarin?
CYP450 inhibitors: Fluconazole (anti-fungal)
How does grapefruit juice cause drug interactions?
Grapefruit contains compounds called furanocoumarins that block CYP3A4 enzyme in the small intestine.
The interaction of grapefruit and drugs is more likely in drugs with a high ______ ______ metabolism or a _____ TI.
‘First-pass’
‘Narrow’
Which of the following drug classes is most commonly affected by grapefruit juice: A) Antidepressants B) Statins C) Antibiotics?
B) Statins
What is a potential consequence of consuming grapefruit juice while taking certain medications?
Increased risk of side effects or toxicity due to higher drug levels in the bloodstream.
Give examples of drug classes metabolized by CYP3A4 enzymes.
Statins, Ca+ channel blockers, benzodiazapines, angiotensin II receptor blockers.
Give two examples of CYP450 inducers and drugs they effect.
Rifampin - propanolol hydrochloride
Phenytoin - verapamil
Give two examples of CYP450 inhibitors and drugs they effect.
Metronidazole - amioderone
Fluconazole - warfarin
