Pharmacology Quiz #26: Cytochrome P-450 Interactions

1. A 45-year-old man with a history of chronic depression and alcoholism is started on a new medication regimen that includes fluoxetine for his depressive symptoms. He is also taking omeprazole for GERD. Which of the following effects is most likely to occur due to an interaction involving the cytochrome P-450 system? 

Question 1 of 5

2. A 60-year-old woman who is being treated for hypertension with amlodipine is prescribed clarithromycin for a respiratory tract infection. What potential interaction should be monitored in this patient due to the effects on the cytochrome P-450 system? 

Question 2 of 5

3. A patient with epilepsy is stabilized on phenytoin therapy. He is prescribed a course of rifampin for latent tuberculosis. Which of the following is the most likely outcome of this drug combination due to cytochrome P-450 interactions? 

Question 3 of 5

4. A 55-year-old woman is taking warfarin for atrial fibrillation. She starts taking St. John's wort for depression. After a week, she presents with symptoms of a subtherapeutic anticoagulant effect. Which of the following best explains this patient's presentation? 

Question 4 of 5

5. A patient with HIV is treated with a regimen that includes ritonavir. Which of the following pharmacologic effects is most likely attributable to ritonavir's effect on the cytochrome P-450 system? 

Question 5 of 5


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