CPJE CPJE Drug Interactions and Therapeutics 2

Question 1

Which class of antibiotics is avoided in patients with myasthenia gravis due to neuromuscular blockade?

Accepted Answer

Fluoroquinolones

Answer

Fluoroquinolones can block neuromuscular transmission and exacerbate weakness in patients with myasthenia gravis.

Question 2

A patient on methotrexate is prescribed trimethoprim. What serious toxicity can result?

Accepted Answer

Severe bone marrow suppression

Answer

Both methotrexate and trimethoprim inhibit dihydrofolate reductase, and their combination causes additive antifolate toxicity including bone marrow suppression.

Question 3

Which substrate is most affected by rifampin co-administration due to strong CYP3A4 induction?

Accepted Answer

Oral contraceptives

Answer

Rifampin is a potent CYP3A4 inducer that significantly reduces plasma levels of oral contraceptives, risking contraceptive failure.

Question 4

Combining ACE inhibitors with potassium-sparing diuretics poses a risk of which electrolyte abnormality?

Accepted Answer

Hyperkalemia

Answer

Both ACE inhibitors and potassium-sparing diuretics reduce potassium excretion, and their combination can cause dangerous hyperkalemia.

Question 5

A patient on phenytoin is started on fluconazole. What is the expected outcome?

Accepted Answer

Phenytoin toxicity due to elevated levels

Answer

Fluconazole inhibits CYP2C9, which metabolizes phenytoin, leading to accumulation and potential toxicity including nystagmus and ataxia.

CPJE - California Pharmacy Jurisprudence Exam Practice Test

CPJE - California Pharmacy Jurisprudence Exam Practice Test

CPJE CPJE Drug Interactions and Therapeutics 2