Pharmacy Clinical Pharmacy 3 — Questions and Answers
Question 1: A 68-year-old diabetic patient on metformin develops acute kidney injury (eGFR 28 mL/min/1.73m²). What is the recommended action?
- Reduce metformin dose by 50%
- Continue metformin with increased monitoring
- Discontinue metformin due to lactic acidosis risk (Correct answer)
- Switch to insulin only if eGFR falls below 15
Correct answer: Discontinue metformin due to lactic acidosis risk
Metformin is contraindicated when eGFR falls below 30 mL/min/1.73m² because accumulation increases lactic acidosis risk.
Question 2: Which antibiotic class is associated with QT prolongation and should be used cautiously with antiarrhythmics?
- Penicillins
- Fluoroquinolones (Correct answer)
- Aminoglycosides
- Carbapenems
Correct answer: Fluoroquinolones
Fluoroquinolones block cardiac hERG potassium channels, prolonging the QT interval and risking torsades de pointes.
Question 3: A patient on phenytoin requires total parenteral nutrition (TPN). What drug interaction is clinically important?
- Phenytoin is absorbed by the TPN tubing, reducing serum levels (Correct answer)
- TPN increases CYP2C9 activity, accelerating phenytoin metabolism
- Phenytoin displaces albumin in TPN, increasing free drug
- TPN has no effect on phenytoin pharmacokinetics
Correct answer: Phenytoin is absorbed by the TPN tubing, reducing serum levels
Phenytoin adsorbs to PVC tubing and is incompatible with dextrose solutions, significantly reducing bioavailability during enteral or IV administration with TPN.
Question 4: A 45-year-old woman is prescribed isotretinoin. Which risk management program must be followed?
- REMS with iPLEDGE (Correct answer)
- MedGuide distribution only
- Black Box Counseling Protocol
- TIRF REMS Access program
Correct answer: REMS with iPLEDGE
Isotretinoin is teratogenic and requires enrollment in the iPLEDGE REMS program to prevent fetal exposure.
Question 5: Which parameter is used to assess aminoglycoside efficacy in concentration-dependent killing?
- Time above MIC (T>MIC)
- Area under the curve to MIC ratio (AUC/MIC)
- Peak concentration to MIC ratio (Cmax/MIC) (Correct answer)
- Trough concentration
Correct answer: Peak concentration to MIC ratio (Cmax/MIC)
Aminoglycosides exhibit concentration-dependent killing; efficacy correlates best with the peak-to-MIC ratio (Cmax/MIC ≥10).
Question 6: A patient receiving heparin develops a drop in platelet count from 280,000 to 90,000 on day 8. What condition should be suspected?
- Disseminated intravascular coagulation
- Heparin-induced thrombocytopenia (HIT) (Correct answer)
- Immune thrombocytopenic purpura
- Thrombotic thrombocytopenic purpura
Correct answer: Heparin-induced thrombocytopenia (HIT)
HIT classically occurs 5–10 days after heparin initiation and is caused by antibodies against the heparin-PF4 complex, requiring immediate heparin cessation.
Question 7: Which hepatic condition requires dose reduction of drugs that are high-extraction-ratio drugs administered orally?
- Mild hepatitis with normal albumin
- Cirrhosis with significantly reduced hepatic blood flow (Correct answer)
- Non-alcoholic fatty liver with preserved function
- Hepatic steatosis without portal hypertension
Correct answer: Cirrhosis with significantly reduced hepatic blood flow
High-extraction drugs (e.g., morphine, propranolol) undergo significant first-pass metabolism; cirrhosis reduces hepatic blood flow and enzyme activity, dramatically increasing oral bioavailability.
Pharmacy Clinical Pharmacy 3
A 68-year-old diabetic patient on metformin develops acute kidney injury (eGFR 28 mL/min/1.73m²).
What is the recommended action?