CAOP Drug Interactions and Contraindications 5

Question 1

Per FDA labeling, what is the maximum daily simvastatin dose for a patient also taking amlodipine?

Accepted Answer

20 mg

Answer

Amlodipine weakly inhibits CYP3A4 and raises simvastatin exposure, so simvastatin should not exceed 20 mg daily to limit myopathy risk.

Question 2

A heart failure patient on lisinopril and spironolactone is also taking an over-the-counter salt substitute. Which lab abnormality is most likely?

Accepted Answer

Hyperkalemia

Answer

ACE inhibitors and spironolactone both reduce potassium excretion, and potassium chloride salt substitutes add a potassium load, causing hyperkalemia.

Question 3

How should oral ciprofloxacin be timed relative to a calcium carbonate antacid?

Accepted Answer

Take ciprofloxacin at least 2 hours before or 6 hours after the antacid

Answer

Polyvalent cations such as calcium, magnesium, aluminum, iron, and zinc chelate fluoroquinolones and markedly reduce their absorption.

Question 4

Which drug combination is contraindicated because of potent CYP1A2 inhibition leading to severe hypotension and sedation?

Accepted Answer

Tizanidine and ciprofloxacin

Answer

Ciprofloxacin and fluvoxamine strongly inhibit CYP1A2, raising tizanidine exposure several-fold, so the combination is contraindicated.

Question 5

A patient on metformin with an eGFR of 40 mL/min/1.73 m2 is scheduled for a CT scan with iodinated contrast. What is recommended?

Accepted Answer

Hold metformin at the time of the procedure and restart 48 hours later after confirming stable renal function

Answer

Contrast can cause acute kidney injury, leading to metformin accumulation and lactic acidosis, so it is held in patients with eGFR 30-60 and resumed after renal function is rechecked.

CAOP - Competency Assessment of Overseas Pharmacist Practice Test

CAOP - Competency Assessment of Overseas Pharmacist Practice Test

CAOP Drug Interactions and Contraindications 5