CAOP Drug Interactions and Contraindications

Question 1

A patient on warfarin is prescribed ibuprofen for pain. What is the primary concern with this combination?

Accepted Answer

Increased bleeding risk due to additive anticoagulation and GI mucosal damage

Answer

NSAIDs like ibuprofen inhibit platelet aggregation and damage the GI mucosa, and can also displace warfarin from protein binding, increasing bleeding risk.

Question 2

Which combination of antihypertensive agents poses the greatest risk of dangerous hyperkalaemia?

Accepted Answer

ACE inhibitor + potassium-sparing diuretic

Answer

ACE inhibitors reduce aldosterone secretion and potassium excretion; combining with potassium-sparing diuretics (e.g., spironolactone) can cause life-threatening hyperkalaemia.

Question 3

A patient taking a monoamine oxidase inhibitor (MAOI) is started on sertraline. What potentially fatal interaction can occur?

Accepted Answer

Serotonin syndrome due to excessive serotonergic activity

Answer

Combining MAOIs with SSRIs can cause serotonin syndrome, a life-threatening condition characterised by hyperthermia, agitation, tremor, and clonus.

Question 4

Amiodarone is added to a patient's regimen that includes digoxin. What is the expected pharmacokinetic outcome?

Accepted Answer

Amiodarone inhibits P-glycoprotein and CYP, increasing digoxin plasma levels

Answer

Amiodarone inhibits P-glycoprotein-mediated renal excretion of digoxin and reduces its volume of distribution, typically doubling digoxin levels and requiring a dose reduction.

Question 5

Metformin should be withheld before and after administration of iodinated contrast media primarily because of the risk of:

Accepted Answer

Contrast-induced nephropathy leading to metformin accumulation and lactic acidosis

Answer

Contrast media can impair renal function; reduced renal clearance allows metformin to accumulate, increasing the risk of potentially fatal lactic acidosis.

CAOP - Competency Assessment of Overseas Pharmacist Practice Test

CAOP - Competency Assessment of Overseas Pharmacist Practice Test

CAOP Drug Interactions and Contraindications