CPJE CPJE Drug Interactions and Therapeutics 1

Question 1

A patient on warfarin is prescribed ciprofloxacin. Which monitoring parameter should the pharmacist prioritize?

Accepted Answer

INR/PT levels

Answer

Ciprofloxacin inhibits warfarin metabolism, increasing anticoagulant effect and bleeding risk, so INR must be monitored closely.

Question 2

Which drug combination is contraindicated due to the risk of serotonin syndrome?

Accepted Answer

Sertraline and linezolid

Answer

Linezolid is an MAO inhibitor; combining it with SSRIs like sertraline can precipitate life-threatening serotonin syndrome.

Question 3

A patient taking simvastatin is started on clarithromycin. What is the primary concern?

Accepted Answer

Increased risk of myopathy/rhabdomyolysis

Answer

Clarithromycin inhibits CYP3A4, dramatically increasing simvastatin levels and the risk of myopathy or rhabdomyolysis.

Question 4

Which interaction requires separating doses by at least 2 hours to prevent reduced drug absorption?

Accepted Answer

Levothyroxine and calcium carbonate

Answer

Calcium carbonate chelates levothyroxine in the GI tract, significantly reducing its absorption if taken simultaneously.

Question 5

A patient on lithium is prescribed ibuprofen for pain. What adverse outcome is most likely?

Accepted Answer

Lithium toxicity due to elevated serum levels

Answer

NSAIDs reduce renal prostaglandin synthesis, decreasing lithium clearance and raising serum lithium to toxic levels.

CPJE - California Pharmacy Jurisprudence Exam Practice Test