PSA Drug Interactions 3

Question 1

A patient on ramipril is prescribed spironolactone for heart failure. What electrolyte abnormality is the primary concern?

Accepted Answer

Hyperkalemia from dual potassium-retaining mechanisms

Answer

Both ACE inhibitors and potassium-sparing diuretics independently reduce renal potassium excretion; their combination creates additive hyperkalemia risk, particularly in those with renal impairment.

Question 2

Which drug combination carries the highest risk of serotonin syndrome?

Accepted Answer

SSRI with a monoamine oxidase inhibitor

Answer

MAOIs prevent serotonin degradation while SSRIs block its reuptake; together they cause massive serotonergic excess, presenting as hyperthermia, tremor, clonus, and autonomic instability.

Question 3

A patient on digoxin 125 mcg daily starts amiodarone for atrial fibrillation. Which mechanism best explains the increased digoxin toxicity risk?

Accepted Answer

Amiodarone inhibits P-glycoprotein, reducing renal and biliary digoxin elimination

Answer

Amiodarone inhibits P-glycoprotein-mediated secretion of digoxin in the kidney and bile duct, causing plasma digoxin concentrations to approximately double.

Question 4

Which drug combination constitutes the renal 'triple whammy' associated with acute kidney injury?

Accepted Answer

NSAIDs + ACE inhibitors (or ARBs) + loop or thiazide diuretics

Answer

NSAIDs reduce efferent arteriolar dilation, ACE inhibitors blunt angiotensin II-mediated efferent constriction, and diuretics cause hypovolemia — together these mechanisms collapse glomerular filtration pressure.

Question 5

Which drug combination creates the greatest additive risk of QT prolongation and torsades de pointes?

Accepted Answer

Amiodarone and sotalol

Answer

Both amiodarone and sotalol independently prolong the cardiac action potential by blocking potassium channels; combining them markedly amplifies QT prolongation and arrhythmia risk.

(PSA) Prescribing Safety Assessment Practice Test

(PSA) Prescribing Safety Assessment Practice Test

PSA Drug Interactions 3