Pharmacy Clinical Pharmacy 5 — Questions and Answers
Question 1: A hospitalized patient on IV ciprofloxacin is transitioned to oral ciprofloxacin for continued treatment. The physician asks if a dose adjustment is needed. What is the best response?
- Reduce the dose by 50% because oral absorption is poor
- No adjustment needed; ciprofloxacin has approximately 70–80% oral bioavailability (Correct answer)
- Double the oral dose to compensate for first-pass metabolism
- Avoid oral ciprofloxacin in hospitalized patients
Correct answer: No adjustment needed; ciprofloxacin has approximately 70–80% oral bioavailability
Ciprofloxacin has approximately 70–80% oral bioavailability, making IV-to-PO conversion straightforward without dose adjustment.
Question 2: A patient with heart failure is started on carvedilol. Which counseling point is most important regarding initial therapy?
- Take with antacids to prevent GI upset
- Start at low doses and titrate slowly to avoid acute decompensation (Correct answer)
- Expect immediate improvement in ejection fraction within one week
- Discontinue if resting heart rate falls below 80 bpm
Correct answer: Start at low doses and titrate slowly to avoid acute decompensation
Beta-blockers in heart failure must be started at low doses and titrated slowly because abrupt initiation can precipitate acute decompensation.
Question 3: Which drug interaction mechanism explains the combination of simvastatin and amiodarone causing myopathy?
- Amiodarone induces CYP3A4, reducing simvastatin levels
- Amiodarone inhibits CYP3A4, increasing simvastatin exposure and myopathy risk (Correct answer)
- Simvastatin inhibits amiodarone metabolism via CYP2D6
- Pharmacodynamic synergism with no kinetic component
Correct answer: Amiodarone inhibits CYP3A4, increasing simvastatin exposure and myopathy risk
Amiodarone inhibits CYP3A4, the primary enzyme metabolizing simvastatin, leading to elevated statin levels and increased risk of myopathy or rhabdomyolysis.
Question 4: A patient presents with opioid overdose. Which agent is first-line reversal therapy and what is its mechanism?
- Flumazenil — benzodiazepine receptor antagonist
- Naloxone — competitive opioid receptor antagonist (Correct answer)
- Physostigmine — acetylcholinesterase inhibitor
- Protamine sulfate — heparin antagonist
Correct answer: Naloxone — competitive opioid receptor antagonist
Naloxone competitively displaces opioids from mu, kappa, and delta receptors, rapidly reversing respiratory depression, sedation, and miosis.
Question 5: Which monitoring parameter is most important during the first month of ACE inhibitor therapy in a hypertensive patient with CKD?
- Serum sodium and hemoglobin
- Blood pressure, serum potassium, and serum creatinine (Correct answer)
- Urine culture and sensitivity
- LFTs and serum albumin
Correct answer: Blood pressure, serum potassium, and serum creatinine
ACE inhibitors can cause hyperkalemia and an initial rise in serum creatinine due to efferent arteriolar dilation; monitoring BP, K+, and SCr is essential.
Question 6: A patient's phenytoin free fraction increases when albumin drops from 4.0 to 2.0 g/dL. What clinical consequence is most likely?
- Therapeutic failure due to reduced total drug level
- Toxicity despite a 'normal' total phenytoin level on lab report (Correct answer)
- No clinical impact because free drug levels remain stable
- Reduced seizure threshold requiring dose increase
Correct answer: Toxicity despite a 'normal' total phenytoin level on lab report
Phenytoin is highly protein-bound; hypoalbuminemia increases free (active) drug fraction, causing toxicity even when total phenytoin appears within the normal range.
Question 7: A pharmacist identifies that a patient is taking two drugs that both prolong the QT interval: haloperidol and azithromycin. What is the most appropriate action?
- Dispense both and document in the patient record
- Contact the prescriber to discuss the additive risk and explore alternatives (Correct answer)
- Substitute azithromycin with clarithromycin, which lacks QT effects
- Reduce haloperidol dose by 50% without prescriber notification
Correct answer: Contact the prescriber to discuss the additive risk and explore alternatives
Combining QT-prolonging agents carries additive risk of torsades de pointes; pharmacists must alert the prescriber and collaboratively assess alternatives or monitoring needs.
Pharmacy Clinical Pharmacy 5
A hospitalized patient on IV ciprofloxacin is transitioned to oral ciprofloxacin for continued treatment.
The physician asks if a dose adjustment is needed.
What is the best response?