MTM Pharmacotherapy Review & Drug Interactions 5

Question 1

A patient on tacrolimus (an immunosuppressant) begins taking St. John's Wort. What outcome is expected?

Accepted Answer

Tacrolimus levels decrease due to CYP3A4 induction, risking organ rejection

Answer

St. John's Wort is a potent CYP3A4 and P-glycoprotein inducer that significantly reduces tacrolimus plasma levels, potentially leading to acute transplant rejection.

Question 2

Which pharmacodynamic interaction best describes the combination of an ACE inhibitor with a potassium-sparing diuretic?

Accepted Answer

Additive hyperkalemia risk due to reduced aldosterone effect from both agents

Answer

Both ACE inhibitors (which reduce aldosterone) and potassium-sparing diuretics (which block aldosterone action) decrease potassium excretion, creating additive hyperkalemia risk.

Question 3

A patient on sustained-release theophylline begins ciprofloxacin. What pharmacokinetic change is anticipated?

Accepted Answer

Increased theophylline levels due to CYP1A2 inhibition

Answer

Ciprofloxacin inhibits CYP1A2, the primary enzyme responsible for theophylline metabolism, leading to elevated theophylline levels and potential toxicity (seizures, arrhythmias).

Question 4

What is the most appropriate intervention when a patient's medication therapy problem involves an adverse drug reaction from a necessary medication?

Accepted Answer

Recommend a dose reduction, symptomatic management, or alternative therapy if available

Answer

In MTM, adverse drug reactions are addressed by assessing severity, considering dose adjustments, adding supportive therapy, or switching to an alternative with a safer profile while maintaining therapeutic goals.

Question 5

A patient taking lithium is started on hydrochlorothiazide for hypertension. What is the mechanism of the resulting interaction?

Accepted Answer

Thiazides cause sodium depletion, triggering compensatory renal lithium reabsorption and toxicity

Answer

Thiazide-induced sodium depletion causes the kidney to compensatorily reabsorb both sodium and lithium in the proximal tubule, reducing lithium clearance and raising serum levels toward toxicity.

(MTM) Medication Therapy Management Board Certification Practice Test

(MTM) Medication Therapy Management Board Certification Practice Test

MTM Pharmacotherapy Review & Drug Interactions 5