Pharmacy Clinical Pharmacy 2 — Questions and Answers
Question 1: A patient on warfarin is started on fluconazole. What is the expected pharmacokinetic interaction?
- Fluconazole induces CYP2C9, decreasing warfarin levels
- Fluconazole inhibits CYP2C9, increasing warfarin levels and bleeding risk (Correct answer)
- Fluconazole induces CYP3A4, increasing warfarin metabolism
- No clinically significant interaction exists
Correct answer: Fluconazole inhibits CYP2C9, increasing warfarin levels and bleeding risk
Fluconazole is a potent CYP2C9 inhibitor that reduces warfarin metabolism, raising INR and bleeding risk.
Question 2: Which parameter best describes the time required to reach steady-state plasma concentration?
- Volume of distribution
- Bioavailability
- Approximately 4-5 half-lives (Correct answer)
- Clearance
Correct answer: Approximately 4-5 half-lives
Steady state is reached after approximately 4-5 half-lives regardless of dose or dosing interval.
Question 3: A patient with a serum creatinine of 2.4 mg/dL requires vancomycin dosing. What adjustment is necessary?
- No adjustment needed; vancomycin is hepatically cleared
- Reduce dose frequency due to decreased renal clearance (Correct answer)
- Increase the loading dose to compensate for altered distribution
- Switch to an oral formulation
Correct answer: Reduce dose frequency due to decreased renal clearance
Vancomycin is renally eliminated, so impaired renal function requires extending the dosing interval to prevent toxicity.
Question 4: A pharmacist reviews a medication therapy management (MTM) encounter. Which of the following is a medication-related problem?
- Patient preference for brand-name drugs
- Unnecessary drug therapy with no medical indication (Correct answer)
- Requesting a 90-day supply for convenience
- Using a pill organizer
Correct answer: Unnecessary drug therapy with no medical indication
Unnecessary drug therapy — taking a medication without a valid clinical indication — is a recognized category of medication-related problems in MTM.
Question 5: Which electrolyte imbalance is most commonly associated with loop diuretic use?
- Hyperkalemia
- Hypernatremia
- Hypokalemia (Correct answer)
- Hypercalcemia
Correct answer: Hypokalemia
Loop diuretics inhibit the Na-K-2Cl transporter, increasing urinary potassium loss and causing hypokalemia.
Question 6: A patient taking lithium presents with nausea, tremor, and a serum lithium level of 1.9 mEq/L. What is the appropriate action?
- Continue current dose and recheck in one week
- Hold lithium and consider dialysis if symptoms worsen (Correct answer)
- Increase the dose to achieve better therapeutic effect
- Add a mood stabilizer and continue lithium unchanged
Correct answer: Hold lithium and consider dialysis if symptoms worsen
A lithium level above 1.5 mEq/L with symptoms indicates toxicity; holding the drug and monitoring for dialysis need is appropriate.
Question 7: Which statement best describes pharmacodynamic tolerance?
- Increased renal clearance of a drug over time
- Decreased receptor sensitivity with repeated drug exposure (Correct answer)
- Faster first-pass metabolism after chronic dosing
- Induction of drug-metabolizing enzymes by the drug itself
Correct answer: Decreased receptor sensitivity with repeated drug exposure
Pharmacodynamic tolerance occurs when receptors downregulate or become desensitized, reducing drug effect at the same concentration.
Pharmacy Clinical Pharmacy 2
A patient on warfarin is started on fluconazole.
What is the expected pharmacokinetic interaction?